Hi
I have encountered a module verification failure when running 2 files
with thin-lto (I hit this bug in the link step in LTO on a really
large program and I reduced to this test case).
~/llvmfb/build-debug/bin/llvm-lto2 run -o c a.o b.o -r a.o,c,px -r
b.o,a,px -r b.o,b,px -r a.o,gv -r b.o,gv
Called function is not the same type as the call!
%2 = call i1 bitcast (i1 (%struct.TA*)* @b to i1 (%0*)*)(%struct.TA* %0)
in function a
LLVM ERROR: Broken function found, compilation aborted!
My understanding why this is happening is roughly as follow. I would
like to check with people whether this is a real bug. And also would
like to help fixing it with other people’s help if it’s a real bug. I
am quite new to this part of LLVM.
1. DICompositeType “SHARED” in a.ll is ODRed with the one in b.ll at load time.
2. %struct.TA.0 (renamed from %struct.TA at load time) = type opaque
and i1 (%struct.TA.0*)* @b in b.ll gets pulled into the destination
module when we are merging in a.ll.
3. We only found out that %struct.TA.0 maps to %struct.TA when we link
in b.ll because of the @gv global variable.
4. Then we have a problem, because declare i1 @b(%struct.TA.0*) in
a.ll should have been remapped due to what we found in #3, but was
not. This eventually leads to the IR verifier failure.
Thanks
-Xin
Commands to reproduce with ToT LLVM:
==============================
~/llvm/build-debug/bin/opt -module-summary -o a.o a.ll
~/llvm/build-debug/bin/opt -module-summary -o b.o b.ll
~/llvm/build-debug/bin/llvm-lto2 run -o c a.o b.o -r a.o,c,px -r
b.o,a,px -r b.o,b,px -r a.o,gv -r b.o,gv
[~/thinltobug]$ cat a.ll
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
%struct.TA = type {}
@gv = dso_local global %struct.TA * zeroinitializer
define i32 @c() !dbg !6 {
bitcast %struct.TA ** @gv to i8*
unreachable
}
!llvm.module.flags = !{!0, !1}
!llvm.dbg.cu = !{!2}
!0 = !{i32 2, !"Debug Info Version", i32 3}
!1 = !{i32 1, !"ThinLTO", i32 0}
!2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3,
retainedTypes: !4)
!3 = !DIFile(filename: "f2", directory: "")
!4 = !{!5}
!5 = !DICompositeType(tag: DW_TAG_class_type, file: !3, flags:
DIFlagFwdDecl, identifier: "SHARED")
!6 = distinct !DISubprogram(unit: !2)
[~/thinltobug]$ cat b.ll
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
%struct.TA = type opaque
@gv = external dso_local global %struct.TA *
define i1 @b(%struct.TA*) {
unreachable
}
define i1 @a(%struct.TA* %a) {
call i1 @b(%struct.TA* %a)
unreachable
}
!llvm.module.flags = !{!0, !1}
!llvm.dbg.cu = !{!2}
!0 = !{i32 2, !"Debug Info Version", i32 3}
!1 = !{i32 1, !"ThinLTO", i32 0}
!2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3,
retainedTypes: !4)
!3 = !DIFile(filename: "f1", directory: "")
!4 = !{!5, !9}
!5 = !DICompositeType(tag: DW_TAG_class_type, file: !3,
templateParams: !6, scope: !8)
!6 = !{!7}
; The reference to @b and struct.TA.0 (renamed) that will be loaded in %a.o
!7 = !DITemplateValueParameter(value: i1 (%struct.TA*)* @b)
!8 = distinct !DISubprogram(unit: !2)
!9 = !DICompositeType(tag: DW_TAG_array_type, identifier: "SHARED",
scope: !8)
> -----Original Message----- > From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of Xin > Tong via llvm-dev > Sent: Friday, July 27, 2018 9:33 PM > To: llvm-dev > Subject: [llvm-dev] ThinLTO Bug ? > > Hi > > I have encountered a module verification failure when running 2 files > with thin-lto (I hit this bug in the link step in LTO on a really > large program and I reduced to this test case). > > > ~/llvmfb/build-debug/bin/llvm-lto2 run -o c a.o b.o -r a.o,c,px -r > b.o,a,px -r b.o,b,px -r a.o,gv -r b.o,gv > Called function is not the same type as the call! > %2 = call i1 bitcast (i1 (%struct.TA*)* @b to i1 (%0*)*)(%struct.TA* %0) > in function a > LLVM ERROR: Broken function found, compilation aborted! > > > My understanding why this is happening is roughly as follow. I would > like to check with people whether this is a real bug. And also would > like to help fixing it with other people’s help if it’s a real bug. I > am quite new to this part of LLVM. > > 1. DICompositeType “SHARED” in a.ll is ODRed with the one in b.ll at load > time.I know relatively little about LTO but I see that in a.ll, "SHARED" is described as a DW_TAG_class_type while in b.ll it is DW_TAG_array_type. This suggests that you have an ODR violation in your source code. ODR violations in LTO tend to exhibit as a "broken module" or "broken function" at link time. It would be nice to diagnose these better, admittedly. --paulr> 2. %struct.TA.0 (renamed from %struct.TA at load time) = type opaque > and i1 (%struct.TA.0*)* @b in b.ll gets pulled into the destination > module when we are merging in a.ll. > 3. We only found out that %struct.TA.0 maps to %struct.TA when we link > in b.ll because of the @gv global variable. > 4. Then we have a problem, because declare i1 @b(%struct.TA.0*) in > a.ll should have been remapped due to what we found in #3, but was > not. This eventually leads to the IR verifier failure. > > Thanks > -Xin > > > Commands to reproduce with ToT LLVM: > ==============================> > ~/llvm/build-debug/bin/opt -module-summary -o a.o a.ll > ~/llvm/build-debug/bin/opt -module-summary -o b.o b.ll > ~/llvm/build-debug/bin/llvm-lto2 run -o c a.o b.o -r a.o,c,px -r > b.o,a,px -r b.o,b,px -r a.o,gv -r b.o,gv > > > > [~/thinltobug]$ cat a.ll > > target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" > > target triple = "x86_64-unknown-linux-gnu" > > %struct.TA = type {} > > > > @gv = dso_local global %struct.TA * zeroinitializer > > define i32 @c() !dbg !6 { > > bitcast %struct.TA ** @gv to i8* > > unreachable > > } > > > > > > !llvm.module.flags = !{!0, !1} > > !llvm.dbg.cu = !{!2} > > !0 = !{i32 2, !"Debug Info Version", i32 3} > > !1 = !{i32 1, !"ThinLTO", i32 0} > > !2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, > retainedTypes: !4) > > !3 = !DIFile(filename: "f2", directory: "") > > !4 = !{!5} > > !5 = !DICompositeType(tag: DW_TAG_class_type, file: !3, flags: > DIFlagFwdDecl, identifier: "SHARED") > > !6 = distinct !DISubprogram(unit: !2) > > > > [~/thinltobug]$ cat b.ll > > target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" > > target triple = "x86_64-unknown-linux-gnu" > > > > %struct.TA = type opaque > > > > @gv = external dso_local global %struct.TA * > > > > define i1 @b(%struct.TA*) { > > unreachable > > } > > > > define i1 @a(%struct.TA* %a) { > > call i1 @b(%struct.TA* %a) > > unreachable > > } > > > > !llvm.module.flags = !{!0, !1} > > !llvm.dbg.cu = !{!2} > > !0 = !{i32 2, !"Debug Info Version", i32 3} > > !1 = !{i32 1, !"ThinLTO", i32 0} > > !2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, > retainedTypes: !4) > > !3 = !DIFile(filename: "f1", directory: "") > > !4 = !{!5, !9} > > !5 = !DICompositeType(tag: DW_TAG_class_type, file: !3, > templateParams: !6, scope: !8) > > !6 = !{!7} > > > > ; The reference to @b and struct.TA.0 (renamed) that will be loaded in > %a.o > > > > !7 = !DITemplateValueParameter(value: i1 (%struct.TA*)* @b) > > !8 = distinct !DISubprogram(unit: !2) > > > > !9 = !DICompositeType(tag: DW_TAG_array_type, identifier: "SHARED", scope: > !8) > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
On Mon, Jul 30, 2018 at 6:52 AM <paul.robinson at sony.com> wrote:> > > > > -----Original Message----- > > From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of Xin > > Tong via llvm-dev > > Sent: Friday, July 27, 2018 9:33 PM > > To: llvm-dev > > Subject: [llvm-dev] ThinLTO Bug ? > > > > Hi > > > > I have encountered a module verification failure when running 2 files > > with thin-lto (I hit this bug in the link step in LTO on a really > > large program and I reduced to this test case). > > > > > > ~/llvmfb/build-debug/bin/llvm-lto2 run -o c a.o b.o -r a.o,c,px -r > > b.o,a,px -r b.o,b,px -r a.o,gv -r b.o,gv > > Called function is not the same type as the call! > > %2 = call i1 bitcast (i1 (%struct.TA*)* @b to i1 (%0*)*)(%struct.TA* %0) > > in function a > > LLVM ERROR: Broken function found, compilation aborted! > > > > > > My understanding why this is happening is roughly as follow. I would > > like to check with people whether this is a real bug. And also would > > like to help fixing it with other people’s help if it’s a real bug. I > > am quite new to this part of LLVM. > > > > 1. DICompositeType “SHARED” in a.ll is ODRed with the one in b.ll at load > > time. > > I know relatively little about LTO but I see that in a.ll, "SHARED" is > described as a DW_TAG_class_type while in b.ll it is DW_TAG_array_type. > This suggests that you have an ODR violation in your source code. >Hi Paul Thanks for pointing it out. I fixed this by making in b.ll and the same failure persists. !9 = !DICompositeType(tag: DW_TAG_class_type, file: !3, identifier: "SHARED", scope: !8) -Xin> ODR violations in LTO tend to exhibit as a "broken module" or "broken > function" at link time. It would be nice to diagnose these better, > admittedly. > --paulr > > > 2. %struct.TA.0 (renamed from %struct.TA at load time) = type opaque > > and i1 (%struct.TA.0*)* @b in b.ll gets pulled into the destination > > module when we are merging in a.ll. > > 3. We only found out that %struct.TA.0 maps to %struct.TA when we link > > in b.ll because of the @gv global variable. > > 4. Then we have a problem, because declare i1 @b(%struct.TA.0*) in > > a.ll should have been remapped due to what we found in #3, but was > > not. This eventually leads to the IR verifier failure. > > > > Thanks > > -Xin > > > > > > Commands to reproduce with ToT LLVM: > > ==============================> > > > ~/llvm/build-debug/bin/opt -module-summary -o a.o a.ll > > ~/llvm/build-debug/bin/opt -module-summary -o b.o b.ll > > ~/llvm/build-debug/bin/llvm-lto2 run -o c a.o b.o -r a.o,c,px -r > > b.o,a,px -r b.o,b,px -r a.o,gv -r b.o,gv > > > > > > > > [~/thinltobug]$ cat a.ll > > > > target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" > > > > target triple = "x86_64-unknown-linux-gnu" > > > > %struct.TA = type {} > > > > > > > > @gv = dso_local global %struct.TA * zeroinitializer > > > > define i32 @c() !dbg !6 { > > > > bitcast %struct.TA ** @gv to i8* > > > > unreachable > > > > } > > > > > > > > > > > > !llvm.module.flags = !{!0, !1} > > > > !llvm.dbg.cu = !{!2} > > > > !0 = !{i32 2, !"Debug Info Version", i32 3} > > > > !1 = !{i32 1, !"ThinLTO", i32 0} > > > > !2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, > > retainedTypes: !4) > > > > !3 = !DIFile(filename: "f2", directory: "") > > > > !4 = !{!5} > > > > !5 = !DICompositeType(tag: DW_TAG_class_type, file: !3, flags: > > DIFlagFwdDecl, identifier: "SHARED") > > > > !6 = distinct !DISubprogram(unit: !2) > > > > > > > > [~/thinltobug]$ cat b.ll > > > > target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" > > > > target triple = "x86_64-unknown-linux-gnu" > > > > > > > > %struct.TA = type opaque > > > > > > > > @gv = external dso_local global %struct.TA * > > > > > > > > define i1 @b(%struct.TA*) { > > > > unreachable > > > > } > > > > > > > > define i1 @a(%struct.TA* %a) { > > > > call i1 @b(%struct.TA* %a) > > > > unreachable > > > > } > > > > > > > > !llvm.module.flags = !{!0, !1} > > > > !llvm.dbg.cu = !{!2} > > > > !0 = !{i32 2, !"Debug Info Version", i32 3} > > > > !1 = !{i32 1, !"ThinLTO", i32 0} > > > > !2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, > > retainedTypes: !4) > > > > !3 = !DIFile(filename: "f1", directory: "") > > > > !4 = !{!5, !9} > > > > !5 = !DICompositeType(tag: DW_TAG_class_type, file: !3, > > templateParams: !6, scope: !8) > > > > !6 = !{!7} > > > > > > > > ; The reference to @b and struct.TA.0 (renamed) that will be loaded in > > %a.o > > > > > > > > !7 = !DITemplateValueParameter(value: i1 (%struct.TA*)* @b) > > > > !8 = distinct !DISubprogram(unit: !2) > > > > > > > > !9 = !DICompositeType(tag: DW_TAG_array_type, identifier: "SHARED", scope: > > !8) > > _______________________________________________ > > LLVM Developers mailing list > > llvm-dev at lists.llvm.org > > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev