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Shoaib Meenai via llvm-dev

2017-Jun-28 17:36 UTC

[llvm-dev] Building llvm with clang and lld on arm and the llvm arm backend relocation on position independent code

I've successfully used Peter's patches to get past those relocation
errors.

On 6/28/17, 9:36 AM, "llvm-dev on behalf of Peter Smith via llvm-dev"
<llvm-dev-bounces at lists.llvm.org on behalf of llvm-dev at
lists.llvm.org> wrote:

    Yes it should cover the following relocations:
    R_ARM_CALL (ARM BL/BLX)
    R_ARM_JUMP24 (ARM B)
    R_ARM_THM_CALL (Thumb BL/BLX)
    R_ARM_THM_JUMP19 (Thumb conditional B<cc>.w)
    R_ARM_THM_JMP24 (Thumb unconditional B.w)
    
    Peter
    
    
    On 28 June 2017 at 17:31, Alessandro Pistocchi <apukfreelance at
gmail.com> wrote:
    > Oh, so it looks like I hit a bit of a wall there :-) I’ll take a look
thanks.
    >
    > That bug talks about R_ARM_THM_CALL which I assume are thumb related.
    >
    > Will your implementation fix also R_ARM_CALL errors?
    >
    >> On 28 Jun 2017, at 17:15, Peter Smith <peter.smith at
linaro.org> wrote:
    >>
    >> Hello Alessandro,
    >>
    >> The LLD ARM port doesn't currently support range extension
thunks,
    >> these are needed to extend the range of ARM branch relocations when
    >> the size of the executable instructions exceeds the maximum branch
    >> range.
    >>
    >> I have an implementation in review but it is a fairly large change
so
    >> it may take some time to get through the review process, I've
raised
    >>
https://urldefense.proofpoint.com/v2/url?u=https-3A__bugs.llvm.org_show-5Fbug.cgi-3Fid-3D33612&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=RpqKAJtCInfokC4ejkvv1e1hbMx22g7c6-v8JNuzOrY&e=
that has a link to the
    >> Phab reviews. If you are willing to build your own lld with
additional
    >> changes, you might be able to test out those patches.
    >>
    >> Good luck
    >>
    >> Peter
    >>
    >> On 28 June 2017 at 17:09, Alessandro Pistocchi <apukfreelance at
gmail.com> wrote:
    >>>
    >>>> On 27 Jun 2017, at 13:25, Peter Smith <peter.smith at
linaro.org> wrote:
    >>>>
    >>>> Hello Alessandro,
    >>>>
    >>>> Despite the statement in the HowToCrossCompileLLVM guide
"If you’re
    >>>> using Clang as the cross-compiler, there is a problem in
the LLVM ARM
    >>>> back-end that is producing absolute relocations on
    >>>> position-independent code (R_ARM_THM_MOVW_ABS_NC), so for
now, you
    >>>> should disable PIC:" I can't find an existing
upstream PR or any
    >>>> record that this has been fixed. If the ARM backend is
still producing
    >>>> an R_ARM_THM_MOVW_ABS_NC relocation when -fpic is given as
an option
    >>>> then it would be great to get a small reproducible example
in a new
    >>>> PR, or if there is one already to update it.
    >>>>
    >>>> The last time I ran into this error when trying to cross
compile was
    >>>> that a dependency not compiled by clang (libtinfo.a)
library contained
    >>>> an R_ARM_THM_MOVW_ABS_NC relocation. I don't think that
this is the
    >>>> fault of clang/llvm though, I think it was my fault in
installing a
    >>>> non pic compiled version of libtinfo.a (I'm still
trying to learn how
    >>>> Ubuntu multilibs work).
    >>>>
    >>>> Would it be possible for you to share the details of which
objects
    >>>> contain the R_ARM_THM_MOVW_ABS_NC relocations when compiled
-fpic?
    >>>
    >>> Hi, the errors I get do not seen to mention
R_ARM_THM_MOVW_ABS_NC.
    >>>
    >>> The errors are “relocation R_ARM_CALL out of range”.
    >>>
    >>> Today I recompiled everything from scratch with -fPIC to make
sure I had no library compiled without it and I still get the same errors.
    >>>
    >>> Sorry, I could not find any trivial code that has the same
issue yet.
    >>>
    >>> Following is the output of the compilation process:
    >>>
    >>> yawmoo at
yawmoo-MRNM3AP:~/Desktop/clfs/sources/llvm-build-native-with-lld$ cmake --build
.
    >>> [  0%] Built target LLVMDemangle
    >>> [  3%] Built target LLVMSupport
    >>> [  3%] Built target LLVMTableGen
    >>> [  4%] Built target obj.llvm-tblgen
    >>> [  4%] Built target llvm-tblgen
    >>> [  4%] Built target AttributeCompatFuncTableGen
    >>> [  4%] Built target intrinsics_gen
    >>> [  6%] Built target LLVMCore
    >>> [  6%] Built target LLVMIRReader
    >>> [ 13%] Built target LLVMCodeGen
    >>> [ 14%] Built target LLVMSelectionDAG
    >>> [ 14%] Built target LLVMAsmPrinter
    >>> [ 14%] Built target LLVMMIRParser
    >>> [ 14%] Built target LLVMGlobalISel
    >>> [ 14%] Built target LLVMBinaryFormat
    >>> [ 14%] Built target LLVMBitReader
    >>> [ 16%] Built target LLVMBitWriter
    >>> [ 18%] Built target LLVMTransformUtils
    >>> [ 19%] Built target LLVMInstrumentation
    >>> [ 19%] Built target LLVMInstCombine
    >>> [ 22%] Built target LLVMScalarOpts
    >>> [ 22%] Built target LLVMipo
    >>> [ 24%] Built target LLVMVectorize
    >>> [ 24%] Built target LLVMHello_exports
    >>> [ 24%] Built target LLVMHello
    >>> [ 26%] Built target LLVMObjCARCOpts
    >>> [ 26%] Built target LLVMCoroutines
    >>> [ 26%] Built target LLVMLinker
    >>> [ 29%] Built target LLVMAnalysis
    >>> [ 29%] Built target llvm_vcsrevision_h
    >>> [ 29%] Built target LLVMLTO
    >>> [ 32%] Built target LLVMMC
    >>> [ 32%] Built target LLVMMCParser
    >>> [ 32%] Built target LLVMMCDisassembler
    >>> [ 32%] Built target LLVMObject
    >>> [ 32%] Built target LLVMObjectYAML
    >>> [ 34%] Built target LLVMOption
    >>> [ 36%] Built target LLVMDebugInfoDWARF
    >>> [ 36%] Built target LLVMDebugInfoMSF
    >>> [ 37%] Built target LLVMDebugInfoCodeView
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    >>> [ 42%] Built target LLVMSymbolize
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    >>> [ 42%] Built target LLVMInterpreter
    >>> [ 42%] Built target LLVMMCJIT
    >>> [ 42%] Built target LLVMOrcJIT
    >>> [ 42%] Built target LLVMRuntimeDyld
    >>> [ 42%] Built target LLVMTarget
    >>> [ 44%] Built target ARMCommonTableGen
    >>> [ 45%] Built target LLVMARMCodeGen
    >>> [ 45%] Built target LLVMARMInfo
    >>> [ 45%] Built target LLVMARMAsmParser
    >>> [ 45%] Built target LLVMARMDisassembler
    >>> [ 45%] Built target LLVMARMAsmPrinter
    >>> [ 45%] Built target LLVMARMDesc
    >>> [ 47%] Built target LLVMAsmParser
    >>> [ 47%] Built target LLVMLineEditor
    >>> [ 47%] Built target LLVMProfileData
    >>> [ 47%] Built target LLVMCoverage
    >>> [ 49%] Built target LLVMFuzzerNoMainObjects
    >>> [ 49%] Built target LLVMFuzzerNoMain
    >>> [ 49%] Built target LLVMFuzzer
    >>> [ 49%] Built target LLVMPasses
    >>> [ 49%] Built target LibOptionsTableGen
    >>> [ 49%] Built target LLVMLibDriver
    >>> [ 49%] Built target LLVMXRay
    >>> [ 49%] Built target gtest
    >>> [ 49%] Built target LLVMTestingSupport
    >>> [ 49%] Built target FileCheck
    >>> [ 49%] Built target llvm-PerfectShuffle
    >>> [ 49%] Built target count
    >>> [ 49%] Built target not
    >>> [ 49%] Built target yaml-bench
    >>> [ 49%] Built target LTO_exports
    >>> [ 50%] Built target LTO
    >>> [ 50%] Built target llvm-ar
    >>> [ 50%] Built target llvm-ranlib
    >>> [ 50%] Built target llvm-lib
    >>> [ 50%] Built target llvm-config
    >>> [ 50%] Built target llvm-lto
    >>> [ 50%] Built target llvm-profdata
    >>> [ 50%] Built target obj.clang-tblgen
    >>> [ 50%] Built target clang-tblgen
    >>> [ 55%] Built target clang-headers
    >>> [ 55%] Built target ClangSACheckers
    >>> [ 55%] Built target ClangCommentCommandList
    >>> [ 55%] Built target ClangCommentCommandInfo
    >>> [ 55%] Built target ClangAttrVisitor
    >>> [ 55%] Built target ClangCommentHTMLNamedCharacterReferences
    >>> [ 55%] Built target ClangAttrDump
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    >>> [ 55%] Built target ClangAttrClasses
    >>> [ 55%] Built target ClangStmtNodes
    >>> [ 55%] Built target ClangDeclNodes
    >>> [ 55%] Built target ClangCommentNodes
    >>> [ 55%] Built target ClangCommentHTMLTagsProperties
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    >>> [ 55%] Built target ClangDiagnosticIndexName
    >>> [ 55%] Built target ClangDiagnosticSerialization
    >>> [ 55%] Built target ClangDiagnosticAnalysis
    >>> [ 55%] Built target ClangDiagnosticAST
    >>> [ 55%] Built target ClangDiagnosticParse
    >>> [ 55%] Built target ClangDiagnosticLex
    >>> [ 55%] Built target ClangDiagnosticSema
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    >>> [ 57%] Built target ClangDiagnosticDriver
    >>> [ 57%] Built target ClangAttrList
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    >>> [ 57%] Built target ClangAttrHasAttributeImpl
    >>> [ 57%] Built target ClangDiagnosticCommon
    >>> [ 57%] Built target ClangAttrSubjectMatchRuleList
    >>> [ 57%] Built target ClangARMNeon
    >>> [ 59%] Built target ClangAttrParserStringSwitches
    >>> [ 59%] Built target ClangAttrSubMatchRulesParserStringSwitches
    >>> [ 59%] Built target ClangAttrParsedAttrKinds
    >>> [ 59%] Built target ClangAttrSpellingListIndex
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    >>> [ 59%] Built target ClangAttrParsedAttrImpl
    >>> [ 59%] Built target ClangAttrTemplateInstantiate
    >>> [ 59%] Built target ClangAttrPCHRead
    >>> [ 59%] Built target ClangAttrPCHWrite
    >>> [ 60%] Built target clangBasic
    >>> [ 62%] Built target clangLex
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    >>> [ 63%] Built target clangAST
    >>> [ 63%] Built target clangASTMatchers
    >>> [ 63%] Built target clangDynamicASTMatchers
    >>> [ 65%] Built target clangSema
    >>> [ 67%] Built target clangCodeGen
    >>> [ 68%] Built target clangAnalysis
    >>> [ 68%] Built target clangEdit
    >>> [ 70%] Built target clangRewrite
    >>> [ 72%] Built target clangARCMigrate
    >>> [ 72%] Built target ClangDriverOptions
    >>> [ 75%] Built target clangDriver
    >>> [ 75%] Built target clangSerialization
    >>> [ 77%] Built target clangFrontend
    >>> [ 77%] Built target clangRewriteFrontend
    >>> [ 77%] Built target clangFrontendTool
    >>> [ 77%] Built target clangTooling
    >>> [ 77%] Built target clangToolingCore
    >>> [ 77%] Built target clangToolingRefactor
    >>> [ 77%] Built target clangIndex
    >>> [ 78%] Built target clangStaticAnalyzerCore
    >>> [ 83%] Built target clangStaticAnalyzerCheckers
    >>> [ 83%] Built target clangStaticAnalyzerFrontend
    >>> [ 83%] Built target clangFormat
    >>> [ 85%] Built target diagtool
    >>> [ 85%] Built target clang-offload-bundler
    >>> [ 85%] Linking CXX executable ../../../../bin/clang
    >>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp:(function
llvm::Pass* llvm::callDefaultCtor<llvm::objcarc::ObjCARCAAWrapperPass>()):
relocation R_ARM_CALL out of range
    >>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp:(function
llvm::Pass* llvm::callDefaultCtor<llvm::objcarc::ObjCARCAAWrapperPass>()):
relocation R_ARM_CALL out of range
    >>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/tools/clang/lib/StaticAnalyzer/Core/CallEvent.cpp:(function
clang::ento::CXXDestructorCall*
clang::ento::CallEventManager::create<clang::ento::CXXDestructorCall,
clang::CXXDestructorDecl const*, clang::Stmt const*, clang::ento::MemRegion
const*, bool>(clang::CXXDestructorDecl const*, clang::Stmt const*,
clang::ento::MemRegion const*, bool,
llvm::IntrusiveRefCntPtr<clang::ento::ProgramState const>,
clang::LocationContext const*)): relocation R_ARM_CALL out of range
    >>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp:(function
llvm::Pass* llvm::callDefaultCtor<llvm::objcarc::ObjCARCAAWrapperPass>()):
relocation R_ARM_CALL out of range
    >>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp:(function
llvm::Pass* llvm::callDefaultCtor<llvm::objcarc::ObjCARCAAWrapperPass>()):
relocation R_ARM_CALL out of range
    >>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp:(function
llvm::Pass* llvm::callDefaultCtor<llvm::objcarc::ObjCARCAAWrapperPass>()):
relocation R_ARM_CALL out of range
    >>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAnalysisUtils.cpp:(function
llvm::cl::opt<bool, true, llvm::cl::parser<bool> >::opt<char
[21], llvm::cl::desc, llvm::cl::LocationClass<bool>,
llvm::cl::initializer<bool> >(char const (&) [21], llvm::cl::desc
const&, llvm::cl::LocationClass<bool> const&,
llvm::cl::initializer<bool> const&)): relocation R_ARM_CALL out of
range
    >>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAnalysisUtils.cpp:(function
llvm::cl::opt<bool, true, llvm::cl::parser<bool> >::opt<char
[21], llvm::cl::desc, llvm::cl::LocationClass<bool>,
llvm::cl::initializer<bool> >(char const (&) [21], llvm::cl::desc
const&, llvm::cl::LocationClass<bool> const&,
llvm::cl::initializer<bool> const&)): relocation R_ARM_CALL out of
range
    >>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAnalysisUtils.cpp:(function
llvm::cl::opt<bool, true, llvm::cl::parser<bool> >::opt<char
[21], llvm::cl::desc, llvm::cl::LocationClass<bool>,
llvm::cl::initializer<bool> >(char const (&) [21], llvm::cl::desc
const&, llvm::cl::LocationClass<bool> const&,
llvm::cl::initializer<bool> const&)): relocation R_ARM_CALL out of
range
    >>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAnalysisUtils.cpp:(function
_GLOBAL__sub_I_ObjCARCAnalysisUtils.cpp): relocation R_ARM_CALL out of range
    >>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::operator<<(llvm::raw_ostream&,
llvm::objcarc::ARCInstKind)): relocation R_ARM_CALL out of range
    >>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::operator<<(llvm::raw_ostream&,
llvm::objcarc::ARCInstKind)): relocation R_ARM_CALL out of range
    >>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
    >>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/tools/clang/lib/StaticAnalyzer/Core/CallEvent.cpp:(function
clang::ento::CXXDestructorCall*
clang::ento::CallEventManager::create<clang::ento::CXXDestructorCall,
clang::CXXDestructorDecl const*, clang::Stmt const*, clang::ento::MemRegion
const*, bool>(clang::CXXDestructorDecl const*, clang::Stmt const*,
clang::ento::MemRegion const*, bool,
llvm::IntrusiveRefCntPtr<clang::ento::ProgramState const>,
clang::LocationContext const*)): relocation R_ARM_CALL out of range
    >>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
    >>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
    >>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
    >>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
    >>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
    >>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
    >>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error: too many errors emitted, stopping now (use -error-limit=0 to see all
errors)
    >>> clang-5.0: error: linker command failed with exit code 1 (use
-v to see invocation)
    >>> tools/clang/tools/driver/CMakeFiles/clang.dir/build.make:227:
recipe for target 'bin/clang-5.0' failed
    >>> make[2]: *** [bin/clang-5.0] Error 1
    >>> CMakeFiles/Makefile2:11670: recipe for target
'tools/clang/tools/driver/CMakeFiles/clang.dir/all' failed
    >>> make[1]: ***
[tools/clang/tools/driver/CMakeFiles/clang.dir/all] Error 2
    >>> Makefile:149: recipe for target 'all' failed
    >>> make: *** [all] Error 2
    >>> yawmoo at
yawmoo-MRNM3AP:~/Desktop/clfs/sources/llvm-build-native-with-lld$
    >>>
    >>>
    >>>>
    >>>> Peter
    >>>>
    >>>> On 27 June 2017 at 11:47, Alessandro Pistocchi via llvm-dev
    >>>> <llvm-dev at lists.llvm.org> wrote:
    >>>>>
    >>>>> On 26 Jun 2017, at 16:25, Rui Ueyama <ruiu at
google.com> wrote:
    >>>>>
    >>>>> On Sun, Jun 25, 2017 at 6:40 AM, Alessandro Pistocchi
via llvm-dev
    >>>>> <llvm-dev at lists.llvm.org> wrote:
    >>>>>>
    >>>>>> Hi,
    >>>>>>
    >>>>>> I am trying to build a completely GNU free linux
toolchain for the
    >>>>>> raspberry pi.
    >>>>>>
    >>>>>> I successfully managed to compile llvm and clang
for armv7 hard float (
    >>>>>> both as a cross compiler and as a native compiler )
together with the
    >>>>>> following:
    >>>>>>
    >>>>>> Llvm with clang and lld
    >>>>>> Clang builtins
    >>>>>> Musl libc
    >>>>>> libc++, libc++abi, libunwind
    >>>>>>
    >>>>>> All works well with the only thing to notice being
the need to use -fPIC
    >>>>>> in order to access some library functions when my
own c/c++ programs access
    >>>>>> those functions.
    >>>>>>
    >>>>>> The fact seems to be that musl libc exports some
symbols as protected (
    >>>>>> probably correctly ) and lld ( probably correctly )
says it cannot preempt
    >>>>>> those symbols.
    >>>>>> For this reason I seem to have to use -fPIC in the
C and CXX flags but
    >>>>>> everything seems to work ok.
    >>>>>
    >>>>>
    >>>>> Is this the same problem mentioned in
    >>>>>
https://urldefense.proofpoint.com/v2/url?u=https-3A__bugs.llvm.org_show-5Fbug.cgi-3Fid-3D32425-3F&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=NukMRJ9yTsw5j3ENYmb5P6xnVjqZDGr_RtEBf88y-aI&e=
    >>>>>
    >>>>>
    >>>>> My aim is to build llvm+clang+lld using llvm+clang+lld
on arm ( using musl,
    >>>>> libc++, libc++abi, libunwind and the clang builtins, no
gcc runtime at all
    >>>>> ).
    >>>>>
    >>>>> I think the fact that lld cannot preempt some symbols
without using -fPIC is
    >>>>> similar to the problem mentioned in
    >>>>>
https://urldefense.proofpoint.com/v2/url?u=https-3A__bugs.llvm.org_show-5Fbug.cgi-3Fid-3D32425&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=9sykAqiCyyRAxvbFBkT7xc41tFV4gbqVNlLPtuZwgEo&e=
.
    >>>>>
    >>>>> However I am not particularly bothered at this stage
about having to use
    >>>>> -fPIC. That would be fine.
    >>>>>
    >>>>> What I am struggling with is that having to use -fPIC
is in conflict with
    >>>>> the arm backend issue that creates bad relocations when
building clang with
    >>>>> -fPIC as mentioned in
https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_docs_HowToCrossCompileLLVM.html&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=ZDjTpKgbVvk-6KPfK36_iXsQkmN0tZo-GFLmojAfWdI&e=
and so
    >>>>> the build with -fPIC fails when building the clang
binary.
    >>>>>
    >>>>> Regarding
https://urldefense.proofpoint.com/v2/url?u=https-3A__bugs.llvm.org_show-5Fbug.cgi-3Fid-3D32425&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=9sykAqiCyyRAxvbFBkT7xc41tFV4gbqVNlLPtuZwgEo&e=
, please notice that
    >>>>> contrary to what is reported there I definitely can
build and execute a C
    >>>>> hello world program without having to use -fPIC.
    >>>>>
    >>>>> It is only some symbols from musl that cannot be
preempted by lld, not all
    >>>>> of them.
    >>>>>
    >>>>> Unfortunately, when building llvm+clang+lld quite a few
of those symbols are
    >>>>> explicitly looked for by cmake and not found unless I
use -fPIC.
    >>>>>
    >>>>> If I go ahead and build without using -fPIC then the
build fails because it
    >>>>> cannot preempt those symbols.
    >>>>>
    >>>>> It looks like a paradox to me and I think the solution
would be to fix the
    >>>>> fact that the arm backend does not like -fPIC as
mentioned in
    >>>>>
https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_docs_HowToCrossCompileLLVM.html&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=ZDjTpKgbVvk-6KPfK36_iXsQkmN0tZo-GFLmojAfWdI&e=
. While it is probably
    >>>>> correct that lld says it cannot preempt protected
symbols, the arm backend
    >>>>> issue is a known issue.
    >>>>>
    >>>>>
    >>>>>>
    >>>>>> Then I tried to use this compiler ( both the cross
compiler and the native
    >>>>>> compiler ) to compile llvm + clang + lld ( I want
to have the toolchain
    >>>>>> built with itself, again without any GNU software
involved ) but when
    >>>>>> building the clang executable I ran into the arm
relocation problems
    >>>>>> mentioned here in the “Hacks” section when using
-fPIC:
    >>>>>>
https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_docs_HowToCrossCompileLLVM.html&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=ZDjTpKgbVvk-6KPfK36_iXsQkmN0tZo-GFLmojAfWdI&e=
.
    >>>>>> On the other hand, I seem to need -fPIC otherwise
cmake fails to find some
    >>>>>> libc functions such as futimes/futimens and many
others. If I use -fPIC for
    >>>>>> CFLAGS but not for CXXFLAGS then cmake finds those
symbols but then
    >>>>>> obviously fails at a later stage with lld unable to
preempt those symbols.
    >>>>>>
    >>>>>> This seems to be a conflict I cannot solve without
someone within the llvm
    >>>>>> team fixing the arm relocation problem. Is there
any estimate of when this
    >>>>>> could happen? I am happy to spend the time testing
any solutions by building
    >>>>>> my own toolchain until it succeeds. Or is there any
other solution?
    >>>>>>
    >>>>>> Thank you,
    >>>>>> Alex
    >>>>>>
    >>>>>>
    >>>>>> _______________________________________________
    >>>>>> LLVM Developers mailing list
    >>>>>> llvm-dev at lists.llvm.org
    >>>>>>
https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.llvm.org_cgi-2Dbin_mailman_listinfo_llvm-2Ddev&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=elMtK81LIlpU0bdvd9Zwk2UtgI9He36ddrHDrVDKt94&e=
    >>>>>
    >>>>>
    >>>>>
    >>>>> _______________________________________________
    >>>>> LLVM Developers mailing list
    >>>>> llvm-dev at lists.llvm.org
    >>>>>
https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.llvm.org_cgi-2Dbin_mailman_listinfo_llvm-2Ddev&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=elMtK81LIlpU0bdvd9Zwk2UtgI9He36ddrHDrVDKt94&e=
    >>>>>
    >>>
    >
    _______________________________________________
    LLVM Developers mailing list
    llvm-dev at lists.llvm.org
   
https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.llvm.org_cgi-2Dbin_mailman_listinfo_llvm-2Ddev&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=elMtK81LIlpU0bdvd9Zwk2UtgI9He36ddrHDrVDKt94&e=

Alessandro Pistocchi via llvm-dev

2017-Jun-28 17:49 UTC

head link

[llvm-dev] Building llvm with clang and lld on arm and the llvm arm backend relocation on position independent code

Cool that looks exciting thanks :-)

Sent from my iPhone
> On 28 Jun 2017, at 19:36, Shoaib Meenai <smeenai at fb.com> wrote:
> 
> I've successfully used Peter's patches to get past those relocation
errors.
> 
> On 6/28/17, 9:36 AM, "llvm-dev on behalf of Peter Smith via
llvm-dev" <llvm-dev-bounces at lists.llvm.org on behalf of llvm-dev at
lists.llvm.org> wrote:
> 
>    Yes it should cover the following relocations:
>    R_ARM_CALL (ARM BL/BLX)
>    R_ARM_JUMP24 (ARM B)
>    R_ARM_THM_CALL (Thumb BL/BLX)
>    R_ARM_THM_JUMP19 (Thumb conditional B<cc>.w)
>    R_ARM_THM_JMP24 (Thumb unconditional B.w)
> 
>    Peter
> 
> 
>>    On 28 June 2017 at 17:31, Alessandro Pistocchi <apukfreelance at
gmail.com> wrote:
>> Oh, so it looks like I hit a bit of a wall there :-) I’ll take a look
thanks.
>> 
>> That bug talks about R_ARM_THM_CALL which I assume are thumb related.
>> 
>> Will your implementation fix also R_ARM_CALL errors?
>> 
>>> On 28 Jun 2017, at 17:15, Peter Smith <peter.smith at
linaro.org> wrote:
>>> 
>>> Hello Alessandro,
>>> 
>>> The LLD ARM port doesn't currently support range extension
thunks,
>>> these are needed to extend the range of ARM branch relocations when
>>> the size of the executable instructions exceeds the maximum branch
>>> range.
>>> 
>>> I have an implementation in review but it is a fairly large change
so
>>> it may take some time to get through the review process, I've
raised
>>>
https://urldefense.proofpoint.com/v2/url?u=https-3A__bugs.llvm.org_show-5Fbug.cgi-3Fid-3D33612&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=RpqKAJtCInfokC4ejkvv1e1hbMx22g7c6-v8JNuzOrY&e=
that has a link to the
>>> Phab reviews. If you are willing to build your own lld with
additional
>>> changes, you might be able to test out those patches.
>>> 
>>> Good luck
>>> 
>>> Peter
>>> 
>>>> On 28 June 2017 at 17:09, Alessandro Pistocchi
<apukfreelance at gmail.com> wrote:
>>>> 
>>>>> On 27 Jun 2017, at 13:25, Peter Smith <peter.smith at
linaro.org> wrote:
>>>>> 
>>>>> Hello Alessandro,
>>>>> 
>>>>> Despite the statement in the HowToCrossCompileLLVM guide
"If you’re
>>>>> using Clang as the cross-compiler, there is a problem in
the LLVM ARM
>>>>> back-end that is producing absolute relocations on
>>>>> position-independent code (R_ARM_THM_MOVW_ABS_NC), so for
now, you
>>>>> should disable PIC:" I can't find an existing
upstream PR or any
>>>>> record that this has been fixed. If the ARM backend is
still producing
>>>>> an R_ARM_THM_MOVW_ABS_NC relocation when -fpic is given as
an option
>>>>> then it would be great to get a small reproducible example
in a new
>>>>> PR, or if there is one already to update it.
>>>>> 
>>>>> The last time I ran into this error when trying to cross
compile was
>>>>> that a dependency not compiled by clang (libtinfo.a)
library contained
>>>>> an R_ARM_THM_MOVW_ABS_NC relocation. I don't think that
this is the
>>>>> fault of clang/llvm though, I think it was my fault in
installing a
>>>>> non pic compiled version of libtinfo.a (I'm still
trying to learn how
>>>>> Ubuntu multilibs work).
>>>>> 
>>>>> Would it be possible for you to share the details of which
objects
>>>>> contain the R_ARM_THM_MOVW_ABS_NC relocations when compiled
-fpic?
>>>> 
>>>> Hi, the errors I get do not seen to mention
R_ARM_THM_MOVW_ABS_NC.
>>>> 
>>>> The errors are “relocation R_ARM_CALL out of range”.
>>>> 
>>>> Today I recompiled everything from scratch with -fPIC to make
sure I had no library compiled without it and I still get the same errors.
>>>> 
>>>> Sorry, I could not find any trivial code that has the same
issue yet.
>>>> 
>>>> Following is the output of the compilation process:
>>>> 
>>>> yawmoo at
yawmoo-MRNM3AP:~/Desktop/clfs/sources/llvm-build-native-with-lld$ cmake --build
.
>>>> [  0%] Built target LLVMDemangle
>>>> [  3%] Built target LLVMSupport
>>>> [  3%] Built target LLVMTableGen
>>>> [  4%] Built target obj.llvm-tblgen
>>>> [  4%] Built target llvm-tblgen
>>>> [  4%] Built target AttributeCompatFuncTableGen
>>>> [  4%] Built target intrinsics_gen
>>>> [  6%] Built target LLVMCore
>>>> [  6%] Built target LLVMIRReader
>>>> [ 13%] Built target LLVMCodeGen
>>>> [ 14%] Built target LLVMSelectionDAG
>>>> [ 14%] Built target LLVMAsmPrinter
>>>> [ 14%] Built target LLVMMIRParser
>>>> [ 14%] Built target LLVMGlobalISel
>>>> [ 14%] Built target LLVMBinaryFormat
>>>> [ 14%] Built target LLVMBitReader
>>>> [ 16%] Built target LLVMBitWriter
>>>> [ 18%] Built target LLVMTransformUtils
>>>> [ 19%] Built target LLVMInstrumentation
>>>> [ 19%] Built target LLVMInstCombine
>>>> [ 22%] Built target LLVMScalarOpts
>>>> [ 22%] Built target LLVMipo
>>>> [ 24%] Built target LLVMVectorize
>>>> [ 24%] Built target LLVMHello_exports
>>>> [ 24%] Built target LLVMHello
>>>> [ 26%] Built target LLVMObjCARCOpts
>>>> [ 26%] Built target LLVMCoroutines
>>>> [ 26%] Built target LLVMLinker
>>>> [ 29%] Built target LLVMAnalysis
>>>> [ 29%] Built target llvm_vcsrevision_h
>>>> [ 29%] Built target LLVMLTO
>>>> [ 32%] Built target LLVMMC
>>>> [ 32%] Built target LLVMMCParser
>>>> [ 32%] Built target LLVMMCDisassembler
>>>> [ 32%] Built target LLVMObject
>>>> [ 32%] Built target LLVMObjectYAML
>>>> [ 34%] Built target LLVMOption
>>>> [ 36%] Built target LLVMDebugInfoDWARF
>>>> [ 36%] Built target LLVMDebugInfoMSF
>>>> [ 37%] Built target LLVMDebugInfoCodeView
>>>> [ 40%] Built target LLVMDebugInfoPDB
>>>> [ 42%] Built target LLVMSymbolize
>>>> [ 42%] Built target LLVMExecutionEngine
>>>> [ 42%] Built target LLVMInterpreter
>>>> [ 42%] Built target LLVMMCJIT
>>>> [ 42%] Built target LLVMOrcJIT
>>>> [ 42%] Built target LLVMRuntimeDyld
>>>> [ 42%] Built target LLVMTarget
>>>> [ 44%] Built target ARMCommonTableGen
>>>> [ 45%] Built target LLVMARMCodeGen
>>>> [ 45%] Built target LLVMARMInfo
>>>> [ 45%] Built target LLVMARMAsmParser
>>>> [ 45%] Built target LLVMARMDisassembler
>>>> [ 45%] Built target LLVMARMAsmPrinter
>>>> [ 45%] Built target LLVMARMDesc
>>>> [ 47%] Built target LLVMAsmParser
>>>> [ 47%] Built target LLVMLineEditor
>>>> [ 47%] Built target LLVMProfileData
>>>> [ 47%] Built target LLVMCoverage
>>>> [ 49%] Built target LLVMFuzzerNoMainObjects
>>>> [ 49%] Built target LLVMFuzzerNoMain
>>>> [ 49%] Built target LLVMFuzzer
>>>> [ 49%] Built target LLVMPasses
>>>> [ 49%] Built target LibOptionsTableGen
>>>> [ 49%] Built target LLVMLibDriver
>>>> [ 49%] Built target LLVMXRay
>>>> [ 49%] Built target gtest
>>>> [ 49%] Built target LLVMTestingSupport
>>>> [ 49%] Built target FileCheck
>>>> [ 49%] Built target llvm-PerfectShuffle
>>>> [ 49%] Built target count
>>>> [ 49%] Built target not
>>>> [ 49%] Built target yaml-bench
>>>> [ 49%] Built target LTO_exports
>>>> [ 50%] Built target LTO
>>>> [ 50%] Built target llvm-ar
>>>> [ 50%] Built target llvm-ranlib
>>>> [ 50%] Built target llvm-lib
>>>> [ 50%] Built target llvm-config
>>>> [ 50%] Built target llvm-lto
>>>> [ 50%] Built target llvm-profdata
>>>> [ 50%] Built target obj.clang-tblgen
>>>> [ 50%] Built target clang-tblgen
>>>> [ 55%] Built target clang-headers
>>>> [ 55%] Built target ClangSACheckers
>>>> [ 55%] Built target ClangCommentCommandList
>>>> [ 55%] Built target ClangCommentCommandInfo
>>>> [ 55%] Built target ClangAttrVisitor
>>>> [ 55%] Built target ClangCommentHTMLNamedCharacterReferences
>>>> [ 55%] Built target ClangAttrDump
>>>> [ 55%] Built target ClangAttrImpl
>>>> [ 55%] Built target ClangAttrClasses
>>>> [ 55%] Built target ClangStmtNodes
>>>> [ 55%] Built target ClangDeclNodes
>>>> [ 55%] Built target ClangCommentNodes
>>>> [ 55%] Built target ClangCommentHTMLTagsProperties
>>>> [ 55%] Built target ClangCommentHTMLTags
>>>> [ 55%] Built target ClangDiagnosticIndexName
>>>> [ 55%] Built target ClangDiagnosticSerialization
>>>> [ 55%] Built target ClangDiagnosticAnalysis
>>>> [ 55%] Built target ClangDiagnosticAST
>>>> [ 55%] Built target ClangDiagnosticParse
>>>> [ 55%] Built target ClangDiagnosticLex
>>>> [ 55%] Built target ClangDiagnosticSema
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>>>> [ 57%] Built target ClangAttrList
>>>> [ 57%] Built target ClangDiagnosticFrontend
>>>> [ 57%] Built target ClangAttrHasAttributeImpl
>>>> [ 57%] Built target ClangDiagnosticCommon
>>>> [ 57%] Built target ClangAttrSubjectMatchRuleList
>>>> [ 57%] Built target ClangARMNeon
>>>> [ 59%] Built target ClangAttrParserStringSwitches
>>>> [ 59%] Built target ClangAttrSubMatchRulesParserStringSwitches
>>>> [ 59%] Built target ClangAttrParsedAttrKinds
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>>>> [ 59%] Built target ClangAttrParsedAttrImpl
>>>> [ 59%] Built target ClangAttrTemplateInstantiate
>>>> [ 59%] Built target ClangAttrPCHRead
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>>>> [ 60%] Built target clangBasic
>>>> [ 62%] Built target clangLex
>>>> [ 62%] Built target clangParse
>>>> [ 63%] Built target clangAST
>>>> [ 63%] Built target clangASTMatchers
>>>> [ 63%] Built target clangDynamicASTMatchers
>>>> [ 65%] Built target clangSema
>>>> [ 67%] Built target clangCodeGen
>>>> [ 68%] Built target clangAnalysis
>>>> [ 68%] Built target clangEdit
>>>> [ 70%] Built target clangRewrite
>>>> [ 72%] Built target clangARCMigrate
>>>> [ 72%] Built target ClangDriverOptions
>>>> [ 75%] Built target clangDriver
>>>> [ 75%] Built target clangSerialization
>>>> [ 77%] Built target clangFrontend
>>>> [ 77%] Built target clangRewriteFrontend
>>>> [ 77%] Built target clangFrontendTool
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>>>> [ 77%] Built target clangToolingCore
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>>>> [ 78%] Built target clangStaticAnalyzerCore
>>>> [ 83%] Built target clangStaticAnalyzerCheckers
>>>> [ 83%] Built target clangStaticAnalyzerFrontend
>>>> [ 83%] Built target clangFormat
>>>> [ 85%] Built target diagtool
>>>> [ 85%] Built target clang-offload-bundler
>>>> [ 85%] Linking CXX executable ../../../../bin/clang
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp:(function
llvm::Pass* llvm::callDefaultCtor<llvm::objcarc::ObjCARCAAWrapperPass>()):
relocation R_ARM_CALL out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp:(function
llvm::Pass* llvm::callDefaultCtor<llvm::objcarc::ObjCARCAAWrapperPass>()):
relocation R_ARM_CALL out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/tools/clang/lib/StaticAnalyzer/Core/CallEvent.cpp:(function
clang::ento::CXXDestructorCall*
clang::ento::CallEventManager::create<clang::ento::CXXDestructorCall,
clang::CXXDestructorDecl const*, clang::Stmt const*, clang::ento::MemRegion
const*, bool>(clang::CXXDestructorDecl const*, clang::Stmt const*,
clang::ento::MemRegion const*, bool,
llvm::IntrusiveRefCntPtr<clang::ento::ProgramState const>,
clang::LocationContext const*)): relocation R_ARM_CALL out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp:(function
llvm::Pass* llvm::callDefaultCtor<llvm::objcarc::ObjCARCAAWrapperPass>()):
relocation R_ARM_CALL out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp:(function
llvm::Pass* llvm::callDefaultCtor<llvm::objcarc::ObjCARCAAWrapperPass>()):
relocation R_ARM_CALL out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp:(function
llvm::Pass* llvm::callDefaultCtor<llvm::objcarc::ObjCARCAAWrapperPass>()):
relocation R_ARM_CALL out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAnalysisUtils.cpp:(function
llvm::cl::opt<bool, true, llvm::cl::parser<bool> >::opt<char
[21], llvm::cl::desc, llvm::cl::LocationClass<bool>,
llvm::cl::initializer<bool> >(char const (&) [21], llvm::cl::desc
const&, llvm::cl::LocationClass<bool> const&,
llvm::cl::initializer<bool> const&)): relocation R_ARM_CALL out of
range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAnalysisUtils.cpp:(function
llvm::cl::opt<bool, true, llvm::cl::parser<bool> >::opt<char
[21], llvm::cl::desc, llvm::cl::LocationClass<bool>,
llvm::cl::initializer<bool> >(char const (&) [21], llvm::cl::desc
const&, llvm::cl::LocationClass<bool> const&,
llvm::cl::initializer<bool> const&)): relocation R_ARM_CALL out of
range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAnalysisUtils.cpp:(function
llvm::cl::opt<bool, true, llvm::cl::parser<bool> >::opt<char
[21], llvm::cl::desc, llvm::cl::LocationClass<bool>,
llvm::cl::initializer<bool> >(char const (&) [21], llvm::cl::desc
const&, llvm::cl::LocationClass<bool> const&,
llvm::cl::initializer<bool> const&)): relocation R_ARM_CALL out of
range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAnalysisUtils.cpp:(function
_GLOBAL__sub_I_ObjCARCAnalysisUtils.cpp): relocation R_ARM_CALL out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::operator<<(llvm::raw_ostream&,
llvm::objcarc::ARCInstKind)): relocation R_ARM_CALL out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::operator<<(llvm::raw_ostream&,
llvm::objcarc::ARCInstKind)): relocation R_ARM_CALL out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/tools/clang/lib/StaticAnalyzer/Core/CallEvent.cpp:(function
clang::ento::CXXDestructorCall*
clang::ento::CallEventManager::create<clang::ento::CXXDestructorCall,
clang::CXXDestructorDecl const*, clang::Stmt const*, clang::ento::MemRegion
const*, bool>(clang::CXXDestructorDecl const*, clang::Stmt const*,
clang::ento::MemRegion const*, bool,
llvm::IntrusiveRefCntPtr<clang::ento::ProgramState const>,
clang::LocationContext const*)): relocation R_ARM_CALL out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error: too many errors emitted, stopping now (use -error-limit=0 to see all
errors)
>>>> clang-5.0: error: linker command failed with exit code 1 (use
-v to see invocation)
>>>> tools/clang/tools/driver/CMakeFiles/clang.dir/build.make:227:
recipe for target 'bin/clang-5.0' failed
>>>> make[2]: *** [bin/clang-5.0] Error 1
>>>> CMakeFiles/Makefile2:11670: recipe for target
'tools/clang/tools/driver/CMakeFiles/clang.dir/all' failed
>>>> make[1]: ***
[tools/clang/tools/driver/CMakeFiles/clang.dir/all] Error 2
>>>> Makefile:149: recipe for target 'all' failed
>>>> make: *** [all] Error 2
>>>> yawmoo at
yawmoo-MRNM3AP:~/Desktop/clfs/sources/llvm-build-native-with-lld$
>>>> 
>>>> 
>>>>> 
>>>>> Peter
>>>>> 
>>>>> On 27 June 2017 at 11:47, Alessandro Pistocchi via llvm-dev
>>>>> <llvm-dev at lists.llvm.org> wrote:
>>>>>> 
>>>>>> On 26 Jun 2017, at 16:25, Rui Ueyama <ruiu at
google.com> wrote:
>>>>>> 
>>>>>> On Sun, Jun 25, 2017 at 6:40 AM, Alessandro Pistocchi
via llvm-dev
>>>>>> <llvm-dev at lists.llvm.org> wrote:
>>>>>>> 
>>>>>>> Hi,
>>>>>>> 
>>>>>>> I am trying to build a completely GNU free linux
toolchain for the
>>>>>>> raspberry pi.
>>>>>>> 
>>>>>>> I successfully managed to compile llvm and clang
for armv7 hard float (
>>>>>>> both as a cross compiler and as a native compiler )
together with the
>>>>>>> following:
>>>>>>> 
>>>>>>> Llvm with clang and lld
>>>>>>> Clang builtins
>>>>>>> Musl libc
>>>>>>> libc++, libc++abi, libunwind
>>>>>>> 
>>>>>>> All works well with the only thing to notice being
the need to use -fPIC
>>>>>>> in order to access some library functions when my
own c/c++ programs access
>>>>>>> those functions.
>>>>>>> 
>>>>>>> The fact seems to be that musl libc exports some
symbols as protected (
>>>>>>> probably correctly ) and lld ( probably correctly )
says it cannot preempt
>>>>>>> those symbols.
>>>>>>> For this reason I seem to have to use -fPIC in the
C and CXX flags but
>>>>>>> everything seems to work ok.
>>>>>> 
>>>>>> 
>>>>>> Is this the same problem mentioned in
>>>>>>
https://urldefense.proofpoint.com/v2/url?u=https-3A__bugs.llvm.org_show-5Fbug.cgi-3Fid-3D32425-3F&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=NukMRJ9yTsw5j3ENYmb5P6xnVjqZDGr_RtEBf88y-aI&e=
>>>>>> 
>>>>>> 
>>>>>> My aim is to build llvm+clang+lld using llvm+clang+lld
on arm ( using musl,
>>>>>> libc++, libc++abi, libunwind and the clang builtins, no
gcc runtime at all
>>>>>> ).
>>>>>> 
>>>>>> I think the fact that lld cannot preempt some symbols
without using -fPIC is
>>>>>> similar to the problem mentioned in
>>>>>>
https://urldefense.proofpoint.com/v2/url?u=https-3A__bugs.llvm.org_show-5Fbug.cgi-3Fid-3D32425&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=9sykAqiCyyRAxvbFBkT7xc41tFV4gbqVNlLPtuZwgEo&e=
.
>>>>>> 
>>>>>> However I am not particularly bothered at this stage
about having to use
>>>>>> -fPIC. That would be fine.
>>>>>> 
>>>>>> What I am struggling with is that having to use -fPIC
is in conflict with
>>>>>> the arm backend issue that creates bad relocations when
building clang with
>>>>>> -fPIC as mentioned in
https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_docs_HowToCrossCompileLLVM.html&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=ZDjTpKgbVvk-6KPfK36_iXsQkmN0tZo-GFLmojAfWdI&e=
and so
>>>>>> the build with -fPIC fails when building the clang
binary.
>>>>>> 
>>>>>> Regarding
https://urldefense.proofpoint.com/v2/url?u=https-3A__bugs.llvm.org_show-5Fbug.cgi-3Fid-3D32425&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=9sykAqiCyyRAxvbFBkT7xc41tFV4gbqVNlLPtuZwgEo&e=
, please notice that
>>>>>> contrary to what is reported there I definitely can
build and execute a C
>>>>>> hello world program without having to use -fPIC.
>>>>>> 
>>>>>> It is only some symbols from musl that cannot be
preempted by lld, not all
>>>>>> of them.
>>>>>> 
>>>>>> Unfortunately, when building llvm+clang+lld quite a few
of those symbols are
>>>>>> explicitly looked for by cmake and not found unless I
use -fPIC.
>>>>>> 
>>>>>> If I go ahead and build without using -fPIC then the
build fails because it
>>>>>> cannot preempt those symbols.
>>>>>> 
>>>>>> It looks like a paradox to me and I think the solution
would be to fix the
>>>>>> fact that the arm backend does not like -fPIC as
mentioned in
>>>>>>
https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_docs_HowToCrossCompileLLVM.html&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=ZDjTpKgbVvk-6KPfK36_iXsQkmN0tZo-GFLmojAfWdI&e=
. While it is probably
>>>>>> correct that lld says it cannot preempt protected
symbols, the arm backend
>>>>>> issue is a known issue.
>>>>>> 
>>>>>> 
>>>>>>> 
>>>>>>> Then I tried to use this compiler ( both the cross
compiler and the native
>>>>>>> compiler ) to compile llvm + clang + lld ( I want
to have the toolchain
>>>>>>> built with itself, again without any GNU software
involved ) but when
>>>>>>> building the clang executable I ran into the arm
relocation problems
>>>>>>> mentioned here in the “Hacks” section when using
-fPIC:
>>>>>>>
https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_docs_HowToCrossCompileLLVM.html&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=ZDjTpKgbVvk-6KPfK36_iXsQkmN0tZo-GFLmojAfWdI&e=
.
>>>>>>> On the other hand, I seem to need -fPIC otherwise
cmake fails to find some
>>>>>>> libc functions such as futimes/futimens and many
others. If I use -fPIC for
>>>>>>> CFLAGS but not for CXXFLAGS then cmake finds those
symbols but then
>>>>>>> obviously fails at a later stage with lld unable to
preempt those symbols.
>>>>>>> 
>>>>>>> This seems to be a conflict I cannot solve without
someone within the llvm
>>>>>>> team fixing the arm relocation problem. Is there
any estimate of when this
>>>>>>> could happen? I am happy to spend the time testing
any solutions by building
>>>>>>> my own toolchain until it succeeds. Or is there any
other solution?
>>>>>>> 
>>>>>>> Thank you,
>>>>>>> Alex
>>>>>>> 
>>>>>>> 
>>>>>>> _______________________________________________
>>>>>>> LLVM Developers mailing list
>>>>>>> llvm-dev at lists.llvm.org
>>>>>>>
https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.llvm.org_cgi-2Dbin_mailman_listinfo_llvm-2Ddev&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=elMtK81LIlpU0bdvd9Zwk2UtgI9He36ddrHDrVDKt94&e=
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> _______________________________________________
>>>>>> LLVM Developers mailing list
>>>>>> llvm-dev at lists.llvm.org
>>>>>>
https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.llvm.org_cgi-2Dbin_mailman_listinfo_llvm-2Ddev&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=elMtK81LIlpU0bdvd9Zwk2UtgI9He36ddrHDrVDKt94&e=
>>>>>> 
>>>> 
>> 
>    _______________________________________________
>    LLVM Developers mailing list
>    llvm-dev at lists.llvm.org
>   
https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.llvm.org_cgi-2Dbin_mailman_listinfo_llvm-2Ddev&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=elMtK81LIlpU0bdvd9Zwk2UtgI9He36ddrHDrVDKt94&e=
> 
>

Alessandro Pistocchi via llvm-dev

2017-Jun-28 17:56 UTC

head link

[llvm-dev] Building llvm with clang and lld on arm and the llvm arm backend relocation on position independent code

Sorry for the noob question: where do I get the patches?

I can see the bug but not a link to the patches ( I don't have a login if
that is the issue )

Sent from my iPhone
> On 28 Jun 2017, at 19:36, Shoaib Meenai <smeenai at fb.com> wrote:
> 
> I've successfully used Peter's patches to get past those relocation
errors.
> 
> On 6/28/17, 9:36 AM, "llvm-dev on behalf of Peter Smith via
llvm-dev" <llvm-dev-bounces at lists.llvm.org on behalf of llvm-dev at
lists.llvm.org> wrote:
> 
>    Yes it should cover the following relocations:
>    R_ARM_CALL (ARM BL/BLX)
>    R_ARM_JUMP24 (ARM B)
>    R_ARM_THM_CALL (Thumb BL/BLX)
>    R_ARM_THM_JUMP19 (Thumb conditional B<cc>.w)
>    R_ARM_THM_JMP24 (Thumb unconditional B.w)
> 
>    Peter
> 
> 
>>    On 28 June 2017 at 17:31, Alessandro Pistocchi <apukfreelance at
gmail.com> wrote:
>> Oh, so it looks like I hit a bit of a wall there :-) I’ll take a look
thanks.
>> 
>> That bug talks about R_ARM_THM_CALL which I assume are thumb related.
>> 
>> Will your implementation fix also R_ARM_CALL errors?
>> 
>>> On 28 Jun 2017, at 17:15, Peter Smith <peter.smith at
linaro.org> wrote:
>>> 
>>> Hello Alessandro,
>>> 
>>> The LLD ARM port doesn't currently support range extension
thunks,
>>> these are needed to extend the range of ARM branch relocations when
>>> the size of the executable instructions exceeds the maximum branch
>>> range.
>>> 
>>> I have an implementation in review but it is a fairly large change
so
>>> it may take some time to get through the review process, I've
raised
>>>
https://urldefense.proofpoint.com/v2/url?u=https-3A__bugs.llvm.org_show-5Fbug.cgi-3Fid-3D33612&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=RpqKAJtCInfokC4ejkvv1e1hbMx22g7c6-v8JNuzOrY&e=
that has a link to the
>>> Phab reviews. If you are willing to build your own lld with
additional
>>> changes, you might be able to test out those patches.
>>> 
>>> Good luck
>>> 
>>> Peter
>>> 
>>>> On 28 June 2017 at 17:09, Alessandro Pistocchi
<apukfreelance at gmail.com> wrote:
>>>> 
>>>>> On 27 Jun 2017, at 13:25, Peter Smith <peter.smith at
linaro.org> wrote:
>>>>> 
>>>>> Hello Alessandro,
>>>>> 
>>>>> Despite the statement in the HowToCrossCompileLLVM guide
"If you’re
>>>>> using Clang as the cross-compiler, there is a problem in
the LLVM ARM
>>>>> back-end that is producing absolute relocations on
>>>>> position-independent code (R_ARM_THM_MOVW_ABS_NC), so for
now, you
>>>>> should disable PIC:" I can't find an existing
upstream PR or any
>>>>> record that this has been fixed. If the ARM backend is
still producing
>>>>> an R_ARM_THM_MOVW_ABS_NC relocation when -fpic is given as
an option
>>>>> then it would be great to get a small reproducible example
in a new
>>>>> PR, or if there is one already to update it.
>>>>> 
>>>>> The last time I ran into this error when trying to cross
compile was
>>>>> that a dependency not compiled by clang (libtinfo.a)
library contained
>>>>> an R_ARM_THM_MOVW_ABS_NC relocation. I don't think that
this is the
>>>>> fault of clang/llvm though, I think it was my fault in
installing a
>>>>> non pic compiled version of libtinfo.a (I'm still
trying to learn how
>>>>> Ubuntu multilibs work).
>>>>> 
>>>>> Would it be possible for you to share the details of which
objects
>>>>> contain the R_ARM_THM_MOVW_ABS_NC relocations when compiled
-fpic?
>>>> 
>>>> Hi, the errors I get do not seen to mention
R_ARM_THM_MOVW_ABS_NC.
>>>> 
>>>> The errors are “relocation R_ARM_CALL out of range”.
>>>> 
>>>> Today I recompiled everything from scratch with -fPIC to make
sure I had no library compiled without it and I still get the same errors.
>>>> 
>>>> Sorry, I could not find any trivial code that has the same
issue yet.
>>>> 
>>>> Following is the output of the compilation process:
>>>> 
>>>> yawmoo at
yawmoo-MRNM3AP:~/Desktop/clfs/sources/llvm-build-native-with-lld$ cmake --build
.
>>>> [  0%] Built target LLVMDemangle
>>>> [  3%] Built target LLVMSupport
>>>> [  3%] Built target LLVMTableGen
>>>> [  4%] Built target obj.llvm-tblgen
>>>> [  4%] Built target llvm-tblgen
>>>> [  4%] Built target AttributeCompatFuncTableGen
>>>> [  4%] Built target intrinsics_gen
>>>> [  6%] Built target LLVMCore
>>>> [  6%] Built target LLVMIRReader
>>>> [ 13%] Built target LLVMCodeGen
>>>> [ 14%] Built target LLVMSelectionDAG
>>>> [ 14%] Built target LLVMAsmPrinter
>>>> [ 14%] Built target LLVMMIRParser
>>>> [ 14%] Built target LLVMGlobalISel
>>>> [ 14%] Built target LLVMBinaryFormat
>>>> [ 14%] Built target LLVMBitReader
>>>> [ 16%] Built target LLVMBitWriter
>>>> [ 18%] Built target LLVMTransformUtils
>>>> [ 19%] Built target LLVMInstrumentation
>>>> [ 19%] Built target LLVMInstCombine
>>>> [ 22%] Built target LLVMScalarOpts
>>>> [ 22%] Built target LLVMipo
>>>> [ 24%] Built target LLVMVectorize
>>>> [ 24%] Built target LLVMHello_exports
>>>> [ 24%] Built target LLVMHello
>>>> [ 26%] Built target LLVMObjCARCOpts
>>>> [ 26%] Built target LLVMCoroutines
>>>> [ 26%] Built target LLVMLinker
>>>> [ 29%] Built target LLVMAnalysis
>>>> [ 29%] Built target llvm_vcsrevision_h
>>>> [ 29%] Built target LLVMLTO
>>>> [ 32%] Built target LLVMMC
>>>> [ 32%] Built target LLVMMCParser
>>>> [ 32%] Built target LLVMMCDisassembler
>>>> [ 32%] Built target LLVMObject
>>>> [ 32%] Built target LLVMObjectYAML
>>>> [ 34%] Built target LLVMOption
>>>> [ 36%] Built target LLVMDebugInfoDWARF
>>>> [ 36%] Built target LLVMDebugInfoMSF
>>>> [ 37%] Built target LLVMDebugInfoCodeView
>>>> [ 40%] Built target LLVMDebugInfoPDB
>>>> [ 42%] Built target LLVMSymbolize
>>>> [ 42%] Built target LLVMExecutionEngine
>>>> [ 42%] Built target LLVMInterpreter
>>>> [ 42%] Built target LLVMMCJIT
>>>> [ 42%] Built target LLVMOrcJIT
>>>> [ 42%] Built target LLVMRuntimeDyld
>>>> [ 42%] Built target LLVMTarget
>>>> [ 44%] Built target ARMCommonTableGen
>>>> [ 45%] Built target LLVMARMCodeGen
>>>> [ 45%] Built target LLVMARMInfo
>>>> [ 45%] Built target LLVMARMAsmParser
>>>> [ 45%] Built target LLVMARMDisassembler
>>>> [ 45%] Built target LLVMARMAsmPrinter
>>>> [ 45%] Built target LLVMARMDesc
>>>> [ 47%] Built target LLVMAsmParser
>>>> [ 47%] Built target LLVMLineEditor
>>>> [ 47%] Built target LLVMProfileData
>>>> [ 47%] Built target LLVMCoverage
>>>> [ 49%] Built target LLVMFuzzerNoMainObjects
>>>> [ 49%] Built target LLVMFuzzerNoMain
>>>> [ 49%] Built target LLVMFuzzer
>>>> [ 49%] Built target LLVMPasses
>>>> [ 49%] Built target LibOptionsTableGen
>>>> [ 49%] Built target LLVMLibDriver
>>>> [ 49%] Built target LLVMXRay
>>>> [ 49%] Built target gtest
>>>> [ 49%] Built target LLVMTestingSupport
>>>> [ 49%] Built target FileCheck
>>>> [ 49%] Built target llvm-PerfectShuffle
>>>> [ 49%] Built target count
>>>> [ 49%] Built target not
>>>> [ 49%] Built target yaml-bench
>>>> [ 49%] Built target LTO_exports
>>>> [ 50%] Built target LTO
>>>> [ 50%] Built target llvm-ar
>>>> [ 50%] Built target llvm-ranlib
>>>> [ 50%] Built target llvm-lib
>>>> [ 50%] Built target llvm-config
>>>> [ 50%] Built target llvm-lto
>>>> [ 50%] Built target llvm-profdata
>>>> [ 50%] Built target obj.clang-tblgen
>>>> [ 50%] Built target clang-tblgen
>>>> [ 55%] Built target clang-headers
>>>> [ 55%] Built target ClangSACheckers
>>>> [ 55%] Built target ClangCommentCommandList
>>>> [ 55%] Built target ClangCommentCommandInfo
>>>> [ 55%] Built target ClangAttrVisitor
>>>> [ 55%] Built target ClangCommentHTMLNamedCharacterReferences
>>>> [ 55%] Built target ClangAttrDump
>>>> [ 55%] Built target ClangAttrImpl
>>>> [ 55%] Built target ClangAttrClasses
>>>> [ 55%] Built target ClangStmtNodes
>>>> [ 55%] Built target ClangDeclNodes
>>>> [ 55%] Built target ClangCommentNodes
>>>> [ 55%] Built target ClangCommentHTMLTagsProperties
>>>> [ 55%] Built target ClangCommentHTMLTags
>>>> [ 55%] Built target ClangDiagnosticIndexName
>>>> [ 55%] Built target ClangDiagnosticSerialization
>>>> [ 55%] Built target ClangDiagnosticAnalysis
>>>> [ 55%] Built target ClangDiagnosticAST
>>>> [ 55%] Built target ClangDiagnosticParse
>>>> [ 55%] Built target ClangDiagnosticLex
>>>> [ 55%] Built target ClangDiagnosticSema
>>>> [ 55%] Built target ClangDiagnosticComment
>>>> [ 57%] Built target ClangDiagnosticGroups
>>>> [ 57%] Built target ClangDiagnosticDriver
>>>> [ 57%] Built target ClangAttrList
>>>> [ 57%] Built target ClangDiagnosticFrontend
>>>> [ 57%] Built target ClangAttrHasAttributeImpl
>>>> [ 57%] Built target ClangDiagnosticCommon
>>>> [ 57%] Built target ClangAttrSubjectMatchRuleList
>>>> [ 57%] Built target ClangARMNeon
>>>> [ 59%] Built target ClangAttrParserStringSwitches
>>>> [ 59%] Built target ClangAttrSubMatchRulesParserStringSwitches
>>>> [ 59%] Built target ClangAttrParsedAttrKinds
>>>> [ 59%] Built target ClangAttrSpellingListIndex
>>>> [ 59%] Built target ClangAttrParsedAttrList
>>>> [ 59%] Built target ClangAttrParsedAttrImpl
>>>> [ 59%] Built target ClangAttrTemplateInstantiate
>>>> [ 59%] Built target ClangAttrPCHRead
>>>> [ 59%] Built target ClangAttrPCHWrite
>>>> [ 60%] Built target clangBasic
>>>> [ 62%] Built target clangLex
>>>> [ 62%] Built target clangParse
>>>> [ 63%] Built target clangAST
>>>> [ 63%] Built target clangASTMatchers
>>>> [ 63%] Built target clangDynamicASTMatchers
>>>> [ 65%] Built target clangSema
>>>> [ 67%] Built target clangCodeGen
>>>> [ 68%] Built target clangAnalysis
>>>> [ 68%] Built target clangEdit
>>>> [ 70%] Built target clangRewrite
>>>> [ 72%] Built target clangARCMigrate
>>>> [ 72%] Built target ClangDriverOptions
>>>> [ 75%] Built target clangDriver
>>>> [ 75%] Built target clangSerialization
>>>> [ 77%] Built target clangFrontend
>>>> [ 77%] Built target clangRewriteFrontend
>>>> [ 77%] Built target clangFrontendTool
>>>> [ 77%] Built target clangTooling
>>>> [ 77%] Built target clangToolingCore
>>>> [ 77%] Built target clangToolingRefactor
>>>> [ 77%] Built target clangIndex
>>>> [ 78%] Built target clangStaticAnalyzerCore
>>>> [ 83%] Built target clangStaticAnalyzerCheckers
>>>> [ 83%] Built target clangStaticAnalyzerFrontend
>>>> [ 83%] Built target clangFormat
>>>> [ 85%] Built target diagtool
>>>> [ 85%] Built target clang-offload-bundler
>>>> [ 85%] Linking CXX executable ../../../../bin/clang
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp:(function
llvm::Pass* llvm::callDefaultCtor<llvm::objcarc::ObjCARCAAWrapperPass>()):
relocation R_ARM_CALL out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp:(function
llvm::Pass* llvm::callDefaultCtor<llvm::objcarc::ObjCARCAAWrapperPass>()):
relocation R_ARM_CALL out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/tools/clang/lib/StaticAnalyzer/Core/CallEvent.cpp:(function
clang::ento::CXXDestructorCall*
clang::ento::CallEventManager::create<clang::ento::CXXDestructorCall,
clang::CXXDestructorDecl const*, clang::Stmt const*, clang::ento::MemRegion
const*, bool>(clang::CXXDestructorDecl const*, clang::Stmt const*,
clang::ento::MemRegion const*, bool,
llvm::IntrusiveRefCntPtr<clang::ento::ProgramState const>,
clang::LocationContext const*)): relocation R_ARM_CALL out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp:(function
llvm::Pass* llvm::callDefaultCtor<llvm::objcarc::ObjCARCAAWrapperPass>()):
relocation R_ARM_CALL out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp:(function
llvm::Pass* llvm::callDefaultCtor<llvm::objcarc::ObjCARCAAWrapperPass>()):
relocation R_ARM_CALL out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp:(function
llvm::Pass* llvm::callDefaultCtor<llvm::objcarc::ObjCARCAAWrapperPass>()):
relocation R_ARM_CALL out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAnalysisUtils.cpp:(function
llvm::cl::opt<bool, true, llvm::cl::parser<bool> >::opt<char
[21], llvm::cl::desc, llvm::cl::LocationClass<bool>,
llvm::cl::initializer<bool> >(char const (&) [21], llvm::cl::desc
const&, llvm::cl::LocationClass<bool> const&,
llvm::cl::initializer<bool> const&)): relocation R_ARM_CALL out of
range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAnalysisUtils.cpp:(function
llvm::cl::opt<bool, true, llvm::cl::parser<bool> >::opt<char
[21], llvm::cl::desc, llvm::cl::LocationClass<bool>,
llvm::cl::initializer<bool> >(char const (&) [21], llvm::cl::desc
const&, llvm::cl::LocationClass<bool> const&,
llvm::cl::initializer<bool> const&)): relocation R_ARM_CALL out of
range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAnalysisUtils.cpp:(function
llvm::cl::opt<bool, true, llvm::cl::parser<bool> >::opt<char
[21], llvm::cl::desc, llvm::cl::LocationClass<bool>,
llvm::cl::initializer<bool> >(char const (&) [21], llvm::cl::desc
const&, llvm::cl::LocationClass<bool> const&,
llvm::cl::initializer<bool> const&)): relocation R_ARM_CALL out of
range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAnalysisUtils.cpp:(function
_GLOBAL__sub_I_ObjCARCAnalysisUtils.cpp): relocation R_ARM_CALL out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::operator<<(llvm::raw_ostream&,
llvm::objcarc::ARCInstKind)): relocation R_ARM_CALL out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::operator<<(llvm::raw_ostream&,
llvm::objcarc::ARCInstKind)): relocation R_ARM_CALL out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/tools/clang/lib/StaticAnalyzer/Core/CallEvent.cpp:(function
clang::ento::CXXDestructorCall*
clang::ento::CallEventManager::create<clang::ento::CXXDestructorCall,
clang::CXXDestructorDecl const*, clang::Stmt const*, clang::ento::MemRegion
const*, bool>(clang::CXXDestructorDecl const*, clang::Stmt const*,
clang::ento::MemRegion const*, bool,
llvm::IntrusiveRefCntPtr<clang::ento::ProgramState const>,
clang::LocationContext const*)): relocation R_ARM_CALL out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
>>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error: too many errors emitted, stopping now (use -error-limit=0 to see all
errors)
>>>> clang-5.0: error: linker command failed with exit code 1 (use
-v to see invocation)
>>>> tools/clang/tools/driver/CMakeFiles/clang.dir/build.make:227:
recipe for target 'bin/clang-5.0' failed
>>>> make[2]: *** [bin/clang-5.0] Error 1
>>>> CMakeFiles/Makefile2:11670: recipe for target
'tools/clang/tools/driver/CMakeFiles/clang.dir/all' failed
>>>> make[1]: ***
[tools/clang/tools/driver/CMakeFiles/clang.dir/all] Error 2
>>>> Makefile:149: recipe for target 'all' failed
>>>> make: *** [all] Error 2
>>>> yawmoo at
yawmoo-MRNM3AP:~/Desktop/clfs/sources/llvm-build-native-with-lld$
>>>> 
>>>> 
>>>>> 
>>>>> Peter
>>>>> 
>>>>> On 27 June 2017 at 11:47, Alessandro Pistocchi via llvm-dev
>>>>> <llvm-dev at lists.llvm.org> wrote:
>>>>>> 
>>>>>> On 26 Jun 2017, at 16:25, Rui Ueyama <ruiu at
google.com> wrote:
>>>>>> 
>>>>>> On Sun, Jun 25, 2017 at 6:40 AM, Alessandro Pistocchi
via llvm-dev
>>>>>> <llvm-dev at lists.llvm.org> wrote:
>>>>>>> 
>>>>>>> Hi,
>>>>>>> 
>>>>>>> I am trying to build a completely GNU free linux
toolchain for the
>>>>>>> raspberry pi.
>>>>>>> 
>>>>>>> I successfully managed to compile llvm and clang
for armv7 hard float (
>>>>>>> both as a cross compiler and as a native compiler )
together with the
>>>>>>> following:
>>>>>>> 
>>>>>>> Llvm with clang and lld
>>>>>>> Clang builtins
>>>>>>> Musl libc
>>>>>>> libc++, libc++abi, libunwind
>>>>>>> 
>>>>>>> All works well with the only thing to notice being
the need to use -fPIC
>>>>>>> in order to access some library functions when my
own c/c++ programs access
>>>>>>> those functions.
>>>>>>> 
>>>>>>> The fact seems to be that musl libc exports some
symbols as protected (
>>>>>>> probably correctly ) and lld ( probably correctly )
says it cannot preempt
>>>>>>> those symbols.
>>>>>>> For this reason I seem to have to use -fPIC in the
C and CXX flags but
>>>>>>> everything seems to work ok.
>>>>>> 
>>>>>> 
>>>>>> Is this the same problem mentioned in
>>>>>>
https://urldefense.proofpoint.com/v2/url?u=https-3A__bugs.llvm.org_show-5Fbug.cgi-3Fid-3D32425-3F&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=NukMRJ9yTsw5j3ENYmb5P6xnVjqZDGr_RtEBf88y-aI&e=
>>>>>> 
>>>>>> 
>>>>>> My aim is to build llvm+clang+lld using llvm+clang+lld
on arm ( using musl,
>>>>>> libc++, libc++abi, libunwind and the clang builtins, no
gcc runtime at all
>>>>>> ).
>>>>>> 
>>>>>> I think the fact that lld cannot preempt some symbols
without using -fPIC is
>>>>>> similar to the problem mentioned in
>>>>>>
https://urldefense.proofpoint.com/v2/url?u=https-3A__bugs.llvm.org_show-5Fbug.cgi-3Fid-3D32425&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=9sykAqiCyyRAxvbFBkT7xc41tFV4gbqVNlLPtuZwgEo&e=
.
>>>>>> 
>>>>>> However I am not particularly bothered at this stage
about having to use
>>>>>> -fPIC. That would be fine.
>>>>>> 
>>>>>> What I am struggling with is that having to use -fPIC
is in conflict with
>>>>>> the arm backend issue that creates bad relocations when
building clang with
>>>>>> -fPIC as mentioned in
https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_docs_HowToCrossCompileLLVM.html&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=ZDjTpKgbVvk-6KPfK36_iXsQkmN0tZo-GFLmojAfWdI&e=
and so
>>>>>> the build with -fPIC fails when building the clang
binary.
>>>>>> 
>>>>>> Regarding
https://urldefense.proofpoint.com/v2/url?u=https-3A__bugs.llvm.org_show-5Fbug.cgi-3Fid-3D32425&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=9sykAqiCyyRAxvbFBkT7xc41tFV4gbqVNlLPtuZwgEo&e=
, please notice that
>>>>>> contrary to what is reported there I definitely can
build and execute a C
>>>>>> hello world program without having to use -fPIC.
>>>>>> 
>>>>>> It is only some symbols from musl that cannot be
preempted by lld, not all
>>>>>> of them.
>>>>>> 
>>>>>> Unfortunately, when building llvm+clang+lld quite a few
of those symbols are
>>>>>> explicitly looked for by cmake and not found unless I
use -fPIC.
>>>>>> 
>>>>>> If I go ahead and build without using -fPIC then the
build fails because it
>>>>>> cannot preempt those symbols.
>>>>>> 
>>>>>> It looks like a paradox to me and I think the solution
would be to fix the
>>>>>> fact that the arm backend does not like -fPIC as
mentioned in
>>>>>>
https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_docs_HowToCrossCompileLLVM.html&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=ZDjTpKgbVvk-6KPfK36_iXsQkmN0tZo-GFLmojAfWdI&e=
. While it is probably
>>>>>> correct that lld says it cannot preempt protected
symbols, the arm backend
>>>>>> issue is a known issue.
>>>>>> 
>>>>>> 
>>>>>>> 
>>>>>>> Then I tried to use this compiler ( both the cross
compiler and the native
>>>>>>> compiler ) to compile llvm + clang + lld ( I want
to have the toolchain
>>>>>>> built with itself, again without any GNU software
involved ) but when
>>>>>>> building the clang executable I ran into the arm
relocation problems
>>>>>>> mentioned here in the “Hacks” section when using
-fPIC:
>>>>>>>
https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_docs_HowToCrossCompileLLVM.html&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=ZDjTpKgbVvk-6KPfK36_iXsQkmN0tZo-GFLmojAfWdI&e=
.
>>>>>>> On the other hand, I seem to need -fPIC otherwise
cmake fails to find some
>>>>>>> libc functions such as futimes/futimens and many
others. If I use -fPIC for
>>>>>>> CFLAGS but not for CXXFLAGS then cmake finds those
symbols but then
>>>>>>> obviously fails at a later stage with lld unable to
preempt those symbols.
>>>>>>> 
>>>>>>> This seems to be a conflict I cannot solve without
someone within the llvm
>>>>>>> team fixing the arm relocation problem. Is there
any estimate of when this
>>>>>>> could happen? I am happy to spend the time testing
any solutions by building
>>>>>>> my own toolchain until it succeeds. Or is there any
other solution?
>>>>>>> 
>>>>>>> Thank you,
>>>>>>> Alex
>>>>>>> 
>>>>>>> 
>>>>>>> _______________________________________________
>>>>>>> LLVM Developers mailing list
>>>>>>> llvm-dev at lists.llvm.org
>>>>>>>
https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.llvm.org_cgi-2Dbin_mailman_listinfo_llvm-2Ddev&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=elMtK81LIlpU0bdvd9Zwk2UtgI9He36ddrHDrVDKt94&e=
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> _______________________________________________
>>>>>> LLVM Developers mailing list
>>>>>> llvm-dev at lists.llvm.org
>>>>>>
https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.llvm.org_cgi-2Dbin_mailman_listinfo_llvm-2Ddev&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=elMtK81LIlpU0bdvd9Zwk2UtgI9He36ddrHDrVDKt94&e=
>>>>>> 
>>>> 
>> 
>    _______________________________________________
>    LLVM Developers mailing list
>    llvm-dev at lists.llvm.org
>   
https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.llvm.org_cgi-2Dbin_mailman_listinfo_llvm-2Ddev&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=elMtK81LIlpU0bdvd9Zwk2UtgI9He36ddrHDrVDKt94&e=
> 
>

Shoaib Meenai via llvm-dev

2017-Jun-28 18:04 UTC

head link

[llvm-dev] Building llvm with clang and lld on arm and the llvm arm backend relocation on position independent code

The bottom of the bug has the revision numbers (e.g. D34035). That one
corresponds to e.g. https://reviews.llvm.org/D34035

There's also https://reviews.llvm.org/D34634 which contains all of
Peter's
patches, but it's not going to rebase cleanly once the individual patches
start going in.

On 6/28/17, 10:56 AM, "Alessandro Pistocchi" <apukfreelance at
gmail.com> wrote:

    Sorry for the noob question: where do I get the patches?
    
    I can see the bug but not a link to the patches ( I don't have a login
if that is the issue )
    
    Sent from my iPhone
    
    > On 28 Jun 2017, at 19:36, Shoaib Meenai <smeenai at fb.com>
wrote:
    > 
    > I've successfully used Peter's patches to get past those
relocation errors.
    > 
    > On 6/28/17, 9:36 AM, "llvm-dev on behalf of Peter Smith via
llvm-dev" <llvm-dev-bounces at lists.llvm.org on behalf of llvm-dev at
lists.llvm.org> wrote:
    > 
    >    Yes it should cover the following relocations:
    >    R_ARM_CALL (ARM BL/BLX)
    >    R_ARM_JUMP24 (ARM B)
    >    R_ARM_THM_CALL (Thumb BL/BLX)
    >    R_ARM_THM_JUMP19 (Thumb conditional B<cc>.w)
    >    R_ARM_THM_JMP24 (Thumb unconditional B.w)
    > 
    >    Peter
    > 
    > 
    >>    On 28 June 2017 at 17:31, Alessandro Pistocchi <apukfreelance
at gmail.com> wrote:
    >> Oh, so it looks like I hit a bit of a wall there :-) I’ll take a
look thanks.
    >> 
    >> That bug talks about R_ARM_THM_CALL which I assume are thumb
related.
    >> 
    >> Will your implementation fix also R_ARM_CALL errors?
    >> 
    >>> On 28 Jun 2017, at 17:15, Peter Smith <peter.smith at
linaro.org> wrote:
    >>> 
    >>> Hello Alessandro,
    >>> 
    >>> The LLD ARM port doesn't currently support range extension
thunks,
    >>> these are needed to extend the range of ARM branch relocations
when
    >>> the size of the executable instructions exceeds the maximum
branch
    >>> range.
    >>> 
    >>> I have an implementation in review but it is a fairly large
change so
    >>> it may take some time to get through the review process,
I've raised
    >>>
https://urldefense.proofpoint.com/v2/url?u=https-3A__bugs.llvm.org_show-5Fbug.cgi-3Fid-3D33612&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=RpqKAJtCInfokC4ejkvv1e1hbMx22g7c6-v8JNuzOrY&e=
that has a link to the
    >>> Phab reviews. If you are willing to build your own lld with
additional
    >>> changes, you might be able to test out those patches.
    >>> 
    >>> Good luck
    >>> 
    >>> Peter
    >>> 
    >>>> On 28 June 2017 at 17:09, Alessandro Pistocchi
<apukfreelance at gmail.com> wrote:
    >>>> 
    >>>>> On 27 Jun 2017, at 13:25, Peter Smith <peter.smith
at linaro.org> wrote:
    >>>>> 
    >>>>> Hello Alessandro,
    >>>>> 
    >>>>> Despite the statement in the HowToCrossCompileLLVM
guide "If you’re
    >>>>> using Clang as the cross-compiler, there is a problem
in the LLVM ARM
    >>>>> back-end that is producing absolute relocations on
    >>>>> position-independent code (R_ARM_THM_MOVW_ABS_NC), so
for now, you
    >>>>> should disable PIC:" I can't find an existing
upstream PR or any
    >>>>> record that this has been fixed. If the ARM backend is
still producing
    >>>>> an R_ARM_THM_MOVW_ABS_NC relocation when -fpic is given
as an option
    >>>>> then it would be great to get a small reproducible
example in a new
    >>>>> PR, or if there is one already to update it.
    >>>>> 
    >>>>> The last time I ran into this error when trying to
cross compile was
    >>>>> that a dependency not compiled by clang (libtinfo.a)
library contained
    >>>>> an R_ARM_THM_MOVW_ABS_NC relocation. I don't think
that this is the
    >>>>> fault of clang/llvm though, I think it was my fault in
installing a
    >>>>> non pic compiled version of libtinfo.a (I'm still
trying to learn how
    >>>>> Ubuntu multilibs work).
    >>>>> 
    >>>>> Would it be possible for you to share the details of
which objects
    >>>>> contain the R_ARM_THM_MOVW_ABS_NC relocations when
compiled -fpic?
    >>>> 
    >>>> Hi, the errors I get do not seen to mention
R_ARM_THM_MOVW_ABS_NC.
    >>>> 
    >>>> The errors are “relocation R_ARM_CALL out of range”.
    >>>> 
    >>>> Today I recompiled everything from scratch with -fPIC to
make sure I had no library compiled without it and I still get the same errors.
    >>>> 
    >>>> Sorry, I could not find any trivial code that has the same
issue yet.
    >>>> 
    >>>> Following is the output of the compilation process:
    >>>> 
    >>>> yawmoo at
yawmoo-MRNM3AP:~/Desktop/clfs/sources/llvm-build-native-with-lld$ cmake --build
.
    >>>> [  0%] Built target LLVMDemangle
    >>>> [  3%] Built target LLVMSupport
    >>>> [  3%] Built target LLVMTableGen
    >>>> [  4%] Built target obj.llvm-tblgen
    >>>> [  4%] Built target llvm-tblgen
    >>>> [  4%] Built target AttributeCompatFuncTableGen
    >>>> [  4%] Built target intrinsics_gen
    >>>> [  6%] Built target LLVMCore
    >>>> [  6%] Built target LLVMIRReader
    >>>> [ 13%] Built target LLVMCodeGen
    >>>> [ 14%] Built target LLVMSelectionDAG
    >>>> [ 14%] Built target LLVMAsmPrinter
    >>>> [ 14%] Built target LLVMMIRParser
    >>>> [ 14%] Built target LLVMGlobalISel
    >>>> [ 14%] Built target LLVMBinaryFormat
    >>>> [ 14%] Built target LLVMBitReader
    >>>> [ 16%] Built target LLVMBitWriter
    >>>> [ 18%] Built target LLVMTransformUtils
    >>>> [ 19%] Built target LLVMInstrumentation
    >>>> [ 19%] Built target LLVMInstCombine
    >>>> [ 22%] Built target LLVMScalarOpts
    >>>> [ 22%] Built target LLVMipo
    >>>> [ 24%] Built target LLVMVectorize
    >>>> [ 24%] Built target LLVMHello_exports
    >>>> [ 24%] Built target LLVMHello
    >>>> [ 26%] Built target LLVMObjCARCOpts
    >>>> [ 26%] Built target LLVMCoroutines
    >>>> [ 26%] Built target LLVMLinker
    >>>> [ 29%] Built target LLVMAnalysis
    >>>> [ 29%] Built target llvm_vcsrevision_h
    >>>> [ 29%] Built target LLVMLTO
    >>>> [ 32%] Built target LLVMMC
    >>>> [ 32%] Built target LLVMMCParser
    >>>> [ 32%] Built target LLVMMCDisassembler
    >>>> [ 32%] Built target LLVMObject
    >>>> [ 32%] Built target LLVMObjectYAML
    >>>> [ 34%] Built target LLVMOption
    >>>> [ 36%] Built target LLVMDebugInfoDWARF
    >>>> [ 36%] Built target LLVMDebugInfoMSF
    >>>> [ 37%] Built target LLVMDebugInfoCodeView
    >>>> [ 40%] Built target LLVMDebugInfoPDB
    >>>> [ 42%] Built target LLVMSymbolize
    >>>> [ 42%] Built target LLVMExecutionEngine
    >>>> [ 42%] Built target LLVMInterpreter
    >>>> [ 42%] Built target LLVMMCJIT
    >>>> [ 42%] Built target LLVMOrcJIT
    >>>> [ 42%] Built target LLVMRuntimeDyld
    >>>> [ 42%] Built target LLVMTarget
    >>>> [ 44%] Built target ARMCommonTableGen
    >>>> [ 45%] Built target LLVMARMCodeGen
    >>>> [ 45%] Built target LLVMARMInfo
    >>>> [ 45%] Built target LLVMARMAsmParser
    >>>> [ 45%] Built target LLVMARMDisassembler
    >>>> [ 45%] Built target LLVMARMAsmPrinter
    >>>> [ 45%] Built target LLVMARMDesc
    >>>> [ 47%] Built target LLVMAsmParser
    >>>> [ 47%] Built target LLVMLineEditor
    >>>> [ 47%] Built target LLVMProfileData
    >>>> [ 47%] Built target LLVMCoverage
    >>>> [ 49%] Built target LLVMFuzzerNoMainObjects
    >>>> [ 49%] Built target LLVMFuzzerNoMain
    >>>> [ 49%] Built target LLVMFuzzer
    >>>> [ 49%] Built target LLVMPasses
    >>>> [ 49%] Built target LibOptionsTableGen
    >>>> [ 49%] Built target LLVMLibDriver
    >>>> [ 49%] Built target LLVMXRay
    >>>> [ 49%] Built target gtest
    >>>> [ 49%] Built target LLVMTestingSupport
    >>>> [ 49%] Built target FileCheck
    >>>> [ 49%] Built target llvm-PerfectShuffle
    >>>> [ 49%] Built target count
    >>>> [ 49%] Built target not
    >>>> [ 49%] Built target yaml-bench
    >>>> [ 49%] Built target LTO_exports
    >>>> [ 50%] Built target LTO
    >>>> [ 50%] Built target llvm-ar
    >>>> [ 50%] Built target llvm-ranlib
    >>>> [ 50%] Built target llvm-lib
    >>>> [ 50%] Built target llvm-config
    >>>> [ 50%] Built target llvm-lto
    >>>> [ 50%] Built target llvm-profdata
    >>>> [ 50%] Built target obj.clang-tblgen
    >>>> [ 50%] Built target clang-tblgen
    >>>> [ 55%] Built target clang-headers
    >>>> [ 55%] Built target ClangSACheckers
    >>>> [ 55%] Built target ClangCommentCommandList
    >>>> [ 55%] Built target ClangCommentCommandInfo
    >>>> [ 55%] Built target ClangAttrVisitor
    >>>> [ 55%] Built target
ClangCommentHTMLNamedCharacterReferences
    >>>> [ 55%] Built target ClangAttrDump
    >>>> [ 55%] Built target ClangAttrImpl
    >>>> [ 55%] Built target ClangAttrClasses
    >>>> [ 55%] Built target ClangStmtNodes
    >>>> [ 55%] Built target ClangDeclNodes
    >>>> [ 55%] Built target ClangCommentNodes
    >>>> [ 55%] Built target ClangCommentHTMLTagsProperties
    >>>> [ 55%] Built target ClangCommentHTMLTags
    >>>> [ 55%] Built target ClangDiagnosticIndexName
    >>>> [ 55%] Built target ClangDiagnosticSerialization
    >>>> [ 55%] Built target ClangDiagnosticAnalysis
    >>>> [ 55%] Built target ClangDiagnosticAST
    >>>> [ 55%] Built target ClangDiagnosticParse
    >>>> [ 55%] Built target ClangDiagnosticLex
    >>>> [ 55%] Built target ClangDiagnosticSema
    >>>> [ 55%] Built target ClangDiagnosticComment
    >>>> [ 57%] Built target ClangDiagnosticGroups
    >>>> [ 57%] Built target ClangDiagnosticDriver
    >>>> [ 57%] Built target ClangAttrList
    >>>> [ 57%] Built target ClangDiagnosticFrontend
    >>>> [ 57%] Built target ClangAttrHasAttributeImpl
    >>>> [ 57%] Built target ClangDiagnosticCommon
    >>>> [ 57%] Built target ClangAttrSubjectMatchRuleList
    >>>> [ 57%] Built target ClangARMNeon
    >>>> [ 59%] Built target ClangAttrParserStringSwitches
    >>>> [ 59%] Built target
ClangAttrSubMatchRulesParserStringSwitches
    >>>> [ 59%] Built target ClangAttrParsedAttrKinds
    >>>> [ 59%] Built target ClangAttrSpellingListIndex
    >>>> [ 59%] Built target ClangAttrParsedAttrList
    >>>> [ 59%] Built target ClangAttrParsedAttrImpl
    >>>> [ 59%] Built target ClangAttrTemplateInstantiate
    >>>> [ 59%] Built target ClangAttrPCHRead
    >>>> [ 59%] Built target ClangAttrPCHWrite
    >>>> [ 60%] Built target clangBasic
    >>>> [ 62%] Built target clangLex
    >>>> [ 62%] Built target clangParse
    >>>> [ 63%] Built target clangAST
    >>>> [ 63%] Built target clangASTMatchers
    >>>> [ 63%] Built target clangDynamicASTMatchers
    >>>> [ 65%] Built target clangSema
    >>>> [ 67%] Built target clangCodeGen
    >>>> [ 68%] Built target clangAnalysis
    >>>> [ 68%] Built target clangEdit
    >>>> [ 70%] Built target clangRewrite
    >>>> [ 72%] Built target clangARCMigrate
    >>>> [ 72%] Built target ClangDriverOptions
    >>>> [ 75%] Built target clangDriver
    >>>> [ 75%] Built target clangSerialization
    >>>> [ 77%] Built target clangFrontend
    >>>> [ 77%] Built target clangRewriteFrontend
    >>>> [ 77%] Built target clangFrontendTool
    >>>> [ 77%] Built target clangTooling
    >>>> [ 77%] Built target clangToolingCore
    >>>> [ 77%] Built target clangToolingRefactor
    >>>> [ 77%] Built target clangIndex
    >>>> [ 78%] Built target clangStaticAnalyzerCore
    >>>> [ 83%] Built target clangStaticAnalyzerCheckers
    >>>> [ 83%] Built target clangStaticAnalyzerFrontend
    >>>> [ 83%] Built target clangFormat
    >>>> [ 85%] Built target diagtool
    >>>> [ 85%] Built target clang-offload-bundler
    >>>> [ 85%] Linking CXX executable ../../../../bin/clang
    >>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp:(function
llvm::Pass* llvm::callDefaultCtor<llvm::objcarc::ObjCARCAAWrapperPass>()):
relocation R_ARM_CALL out of range
    >>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp:(function
llvm::Pass* llvm::callDefaultCtor<llvm::objcarc::ObjCARCAAWrapperPass>()):
relocation R_ARM_CALL out of range
    >>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/tools/clang/lib/StaticAnalyzer/Core/CallEvent.cpp:(function
clang::ento::CXXDestructorCall*
clang::ento::CallEventManager::create<clang::ento::CXXDestructorCall,
clang::CXXDestructorDecl const*, clang::Stmt const*, clang::ento::MemRegion
const*, bool>(clang::CXXDestructorDecl const*, clang::Stmt const*,
clang::ento::MemRegion const*, bool,
llvm::IntrusiveRefCntPtr<clang::ento::ProgramState const>,
clang::LocationContext const*)): relocation R_ARM_CALL out of range
    >>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp:(function
llvm::Pass* llvm::callDefaultCtor<llvm::objcarc::ObjCARCAAWrapperPass>()):
relocation R_ARM_CALL out of range
    >>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp:(function
llvm::Pass* llvm::callDefaultCtor<llvm::objcarc::ObjCARCAAWrapperPass>()):
relocation R_ARM_CALL out of range
    >>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp:(function
llvm::Pass* llvm::callDefaultCtor<llvm::objcarc::ObjCARCAAWrapperPass>()):
relocation R_ARM_CALL out of range
    >>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAnalysisUtils.cpp:(function
llvm::cl::opt<bool, true, llvm::cl::parser<bool> >::opt<char
[21], llvm::cl::desc, llvm::cl::LocationClass<bool>,
llvm::cl::initializer<bool> >(char const (&) [21], llvm::cl::desc
const&, llvm::cl::LocationClass<bool> const&,
llvm::cl::initializer<bool> const&)): relocation R_ARM_CALL out of
range
    >>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAnalysisUtils.cpp:(function
llvm::cl::opt<bool, true, llvm::cl::parser<bool> >::opt<char
[21], llvm::cl::desc, llvm::cl::LocationClass<bool>,
llvm::cl::initializer<bool> >(char const (&) [21], llvm::cl::desc
const&, llvm::cl::LocationClass<bool> const&,
llvm::cl::initializer<bool> const&)): relocation R_ARM_CALL out of
range
    >>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAnalysisUtils.cpp:(function
llvm::cl::opt<bool, true, llvm::cl::parser<bool> >::opt<char
[21], llvm::cl::desc, llvm::cl::LocationClass<bool>,
llvm::cl::initializer<bool> >(char const (&) [21], llvm::cl::desc
const&, llvm::cl::LocationClass<bool> const&,
llvm::cl::initializer<bool> const&)): relocation R_ARM_CALL out of
range
    >>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCAnalysisUtils.cpp:(function
_GLOBAL__sub_I_ObjCARCAnalysisUtils.cpp): relocation R_ARM_CALL out of range
    >>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::operator<<(llvm::raw_ostream&,
llvm::objcarc::ARCInstKind)): relocation R_ARM_CALL out of range
    >>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::operator<<(llvm::raw_ostream&,
llvm::objcarc::ARCInstKind)): relocation R_ARM_CALL out of range
    >>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
    >>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/tools/clang/lib/StaticAnalyzer/Core/CallEvent.cpp:(function
clang::ento::CXXDestructorCall*
clang::ento::CallEventManager::create<clang::ento::CXXDestructorCall,
clang::CXXDestructorDecl const*, clang::Stmt const*, clang::ento::MemRegion
const*, bool>(clang::CXXDestructorDecl const*, clang::Stmt const*,
clang::ento::MemRegion const*, bool,
llvm::IntrusiveRefCntPtr<clang::ento::ProgramState const>,
clang::LocationContext const*)): relocation R_ARM_CALL out of range
    >>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
    >>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
    >>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
    >>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
    >>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
    >>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error:
/home/yawmoo/Desktop/clfs/sources/llvm/lib/Analysis/ObjCARCInstKind.cpp:(function
llvm::objcarc::GetFunctionClass(llvm::Function const*)): relocation R_ARM_CALL
out of range
    >>>> /home/yawmoo/Desktop/clfs/llvm-cross-tools-lld/bin/ld.lld:
error: too many errors emitted, stopping now (use -error-limit=0 to see all
errors)
    >>>> clang-5.0: error: linker command failed with exit code 1
(use -v to see invocation)
    >>>>
tools/clang/tools/driver/CMakeFiles/clang.dir/build.make:227: recipe for target
'bin/clang-5.0' failed
    >>>> make[2]: *** [bin/clang-5.0] Error 1
    >>>> CMakeFiles/Makefile2:11670: recipe for target
'tools/clang/tools/driver/CMakeFiles/clang.dir/all' failed
    >>>> make[1]: ***
[tools/clang/tools/driver/CMakeFiles/clang.dir/all] Error 2
    >>>> Makefile:149: recipe for target 'all' failed
    >>>> make: *** [all] Error 2
    >>>> yawmoo at
yawmoo-MRNM3AP:~/Desktop/clfs/sources/llvm-build-native-with-lld$
    >>>> 
    >>>> 
    >>>>> 
    >>>>> Peter
    >>>>> 
    >>>>> On 27 June 2017 at 11:47, Alessandro Pistocchi via
llvm-dev
    >>>>> <llvm-dev at lists.llvm.org> wrote:
    >>>>>> 
    >>>>>> On 26 Jun 2017, at 16:25, Rui Ueyama <ruiu at
google.com> wrote:
    >>>>>> 
    >>>>>> On Sun, Jun 25, 2017 at 6:40 AM, Alessandro
Pistocchi via llvm-dev
    >>>>>> <llvm-dev at lists.llvm.org> wrote:
    >>>>>>> 
    >>>>>>> Hi,
    >>>>>>> 
    >>>>>>> I am trying to build a completely GNU free
linux toolchain for the
    >>>>>>> raspberry pi.
    >>>>>>> 
    >>>>>>> I successfully managed to compile llvm and
clang for armv7 hard float (
    >>>>>>> both as a cross compiler and as a native
compiler ) together with the
    >>>>>>> following:
    >>>>>>> 
    >>>>>>> Llvm with clang and lld
    >>>>>>> Clang builtins
    >>>>>>> Musl libc
    >>>>>>> libc++, libc++abi, libunwind
    >>>>>>> 
    >>>>>>> All works well with the only thing to notice
being the need to use -fPIC
    >>>>>>> in order to access some library functions when
my own c/c++ programs access
    >>>>>>> those functions.
    >>>>>>> 
    >>>>>>> The fact seems to be that musl libc exports
some symbols as protected (
    >>>>>>> probably correctly ) and lld ( probably
correctly ) says it cannot preempt
    >>>>>>> those symbols.
    >>>>>>> For this reason I seem to have to use -fPIC in
the C and CXX flags but
    >>>>>>> everything seems to work ok.
    >>>>>> 
    >>>>>> 
    >>>>>> Is this the same problem mentioned in
    >>>>>>
https://urldefense.proofpoint.com/v2/url?u=https-3A__bugs.llvm.org_show-5Fbug.cgi-3Fid-3D32425-3F&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=NukMRJ9yTsw5j3ENYmb5P6xnVjqZDGr_RtEBf88y-aI&e=
    >>>>>> 
    >>>>>> 
    >>>>>> My aim is to build llvm+clang+lld using
llvm+clang+lld on arm ( using musl,
    >>>>>> libc++, libc++abi, libunwind and the clang
builtins, no gcc runtime at all
    >>>>>> ).
    >>>>>> 
    >>>>>> I think the fact that lld cannot preempt some
symbols without using -fPIC is
    >>>>>> similar to the problem mentioned in
    >>>>>>
https://urldefense.proofpoint.com/v2/url?u=https-3A__bugs.llvm.org_show-5Fbug.cgi-3Fid-3D32425&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=9sykAqiCyyRAxvbFBkT7xc41tFV4gbqVNlLPtuZwgEo&e=
.
    >>>>>> 
    >>>>>> However I am not particularly bothered at this
stage about having to use
    >>>>>> -fPIC. That would be fine.
    >>>>>> 
    >>>>>> What I am struggling with is that having to use
-fPIC is in conflict with
    >>>>>> the arm backend issue that creates bad relocations
when building clang with
    >>>>>> -fPIC as mentioned in
https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_docs_HowToCrossCompileLLVM.html&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=ZDjTpKgbVvk-6KPfK36_iXsQkmN0tZo-GFLmojAfWdI&e=
and so
    >>>>>> the build with -fPIC fails when building the clang
binary.
    >>>>>> 
    >>>>>> Regarding
https://urldefense.proofpoint.com/v2/url?u=https-3A__bugs.llvm.org_show-5Fbug.cgi-3Fid-3D32425&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=9sykAqiCyyRAxvbFBkT7xc41tFV4gbqVNlLPtuZwgEo&e=
, please notice that
    >>>>>> contrary to what is reported there I definitely can
build and execute a C
    >>>>>> hello world program without having to use -fPIC.
    >>>>>> 
    >>>>>> It is only some symbols from musl that cannot be
preempted by lld, not all
    >>>>>> of them.
    >>>>>> 
    >>>>>> Unfortunately, when building llvm+clang+lld quite a
few of those symbols are
    >>>>>> explicitly looked for by cmake and not found unless
I use -fPIC.
    >>>>>> 
    >>>>>> If I go ahead and build without using -fPIC then
the build fails because it
    >>>>>> cannot preempt those symbols.
    >>>>>> 
    >>>>>> It looks like a paradox to me and I think the
solution would be to fix the
    >>>>>> fact that the arm backend does not like -fPIC as
mentioned in
    >>>>>>
https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_docs_HowToCrossCompileLLVM.html&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=ZDjTpKgbVvk-6KPfK36_iXsQkmN0tZo-GFLmojAfWdI&e=
. While it is probably
    >>>>>> correct that lld says it cannot preempt protected
symbols, the arm backend
    >>>>>> issue is a known issue.
    >>>>>> 
    >>>>>> 
    >>>>>>> 
    >>>>>>> Then I tried to use this compiler ( both the
cross compiler and the native
    >>>>>>> compiler ) to compile llvm + clang + lld ( I
want to have the toolchain
    >>>>>>> built with itself, again without any GNU
software involved ) but when
    >>>>>>> building the clang executable I ran into the
arm relocation problems
    >>>>>>> mentioned here in the “Hacks” section when
using -fPIC:
    >>>>>>>
https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_docs_HowToCrossCompileLLVM.html&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=ZDjTpKgbVvk-6KPfK36_iXsQkmN0tZo-GFLmojAfWdI&e=
.
    >>>>>>> On the other hand, I seem to need -fPIC
otherwise cmake fails to find some
    >>>>>>> libc functions such as futimes/futimens and
many others. If I use -fPIC for
    >>>>>>> CFLAGS but not for CXXFLAGS then cmake finds
those symbols but then
    >>>>>>> obviously fails at a later stage with lld
unable to preempt those symbols.
    >>>>>>> 
    >>>>>>> This seems to be a conflict I cannot solve
without someone within the llvm
    >>>>>>> team fixing the arm relocation problem. Is
there any estimate of when this
    >>>>>>> could happen? I am happy to spend the time
testing any solutions by building
    >>>>>>> my own toolchain until it succeeds. Or is there
any other solution?
    >>>>>>> 
    >>>>>>> Thank you,
    >>>>>>> Alex
    >>>>>>> 
    >>>>>>> 
    >>>>>>> _______________________________________________
    >>>>>>> LLVM Developers mailing list
    >>>>>>> llvm-dev at lists.llvm.org
    >>>>>>>
https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.llvm.org_cgi-2Dbin_mailman_listinfo_llvm-2Ddev&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=elMtK81LIlpU0bdvd9Zwk2UtgI9He36ddrHDrVDKt94&e=
    >>>>>> 
    >>>>>> 
    >>>>>> 
    >>>>>> _______________________________________________
    >>>>>> LLVM Developers mailing list
    >>>>>> llvm-dev at lists.llvm.org
    >>>>>>
https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.llvm.org_cgi-2Dbin_mailman_listinfo_llvm-2Ddev&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=elMtK81LIlpU0bdvd9Zwk2UtgI9He36ddrHDrVDKt94&e=
    >>>>>> 
    >>>> 
    >> 
    >    _______________________________________________
    >    LLVM Developers mailing list
    >    llvm-dev at lists.llvm.org
    >   
https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.llvm.org_cgi-2Dbin_mailman_listinfo_llvm-2Ddev&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=MoG8NHuM6pLu1J1B-yHnV-uqDvXgdp72ydIhDlNyQ9Q&s=elMtK81LIlpU0bdvd9Zwk2UtgI9He36ddrHDrVDKt94&e=
    > 
    >

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