similar to: [LLVMdev] optimizer clobbering EFLAGS

I remember this bug. :) IMO, LLVM should never emit pushf / popf. I'm not sure this patch to fix it ever got committed: http://reviews.llvm.org/D6629 On Wed, Jul 29, 2015 at 3:11 PM, Michael Hordijk <hoffbrinkle at hotmail.com> wrote: > > Using Clang/LLVM 3.6.0 we are observing a case where the optimizations are > clobbering EFLAGS on x86_64. This is inconvenient when the

Agreed, never emit pushf/popf. Sorry I never committed the patch, the cmov issue got hairy and I never got to debugging it :-) I can get back to it if there's interest! On Wed, Jul 29, 2015 at 4:12 PM, Reid Kleckner <rnk at google.com> wrote: > I remember this bug. :) IMO, LLVM should never emit pushf / popf. I'm not > sure this patch to fix it ever got committed: >

Using Clang/LLVM 3.6.0 we are observing a case where the optimizations are clobbering EFLAGS on x86_64. This is inconvenient when the status of bit 9 (IF), which controls interrupts, changes. Here's a simple test program. Assume that the external function foo() modifies the IF bit in EFLAGS. --- #include <stdlib.h> #include <stdbool.h> void foo(void); int a; int bar(void)

Hello llvm-dev list, i am implementing an X86 Machine Pass that at some point needs to push/pop eflags on the stack. This pass is hooked at preRegAlloc and LLVM is 3.7.0. I got two big problems: 1) I didn't found a way to emit a pushfq instruction in a clean way, i.e. with BuildMI(*MBB, MI, DL, TII.get(X86::PUSHF64)). Even if both EFLAGS and RSP are added to the MBB liveins, the Machine

Hi, After reading https://llvm.org/docs/Vectorizers.html#vectorization-of-function-calls I decided to write the following C++ program: #include <cmath> using v4f32 = float __attribute__((__vector_size__(16))); v4f32 fct1(v4f32 x) { v4f32 y; y[0] = std::sin(x[0]); y[1] = std::sin(x[1]); y[2] = std::sin(x[2]); y[3] = std::sin(x[3]); return y; } v4f32 fct2(v4f32 x) { v4f32 y;

One more interesting thing I have noticed is as following : In sqlite3 code consider 3 functions namely sqlite3Update, sqlite3Select and sqlite3Where begin sqlite3WhereBegin is called by both functions sqlite3Update and sqlite3Select but according to CallGraphSCC sqlite3Update is codegen before in that case during RegMask propagation phase default regmask is used for call site of

plain text document attachment (xx-paravirt-core.patch) Paravirt Ops core files. Signed-off-by: Steven Rostedt srostedt@redhat.com Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com> Index: clean-start/arch/x86_64/kernel/paravirt.c =================================================================== --- /dev/null +++ clean-start/arch/x86_64/kernel/paravirt.c @@ -0,0 +1,504 @@ +/*

plain text document attachment (xx-paravirt-core.patch) Paravirt Ops core files. Signed-off-by: Steven Rostedt srostedt@redhat.com Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com> Index: clean-start/arch/x86_64/kernel/paravirt.c =================================================================== --- /dev/null +++ clean-start/arch/x86_64/kernel/paravirt.c @@ -0,0 +1,504 @@ +/*

On 7/29/15 18:35, JF Bastien wrote: > Agreed, never emit pushf/popf. Sorry I never committed the patch, the > cmov issue got hairy and I never got to debugging it :-) > I can get back to it if there's interest! You've definitely got some interest here. I've been looking at your patch on http://reviews.llvm.org/D6629 and I think I'm up to speed on where it's stuck.

On Sun, May 11, 2014 at 8:19 AM, Stephan Tolksdorf <st at quanttec.com> wrote: > Hi, > > When clang/LLVM can't prove that a noexcept function only contains > non-throwing code, it seems to insert an explicit exception handler that > calls std::terminate. Why doesn't clang leave it to the eh personality > function to call std::terminate when an exception is thrown

The attached .ll files seem equivalent, but the resulting asm from 'opt-fail.ll' causes a crash to webkit. I suspect the usage of registers is wrong, can someone take a look ? $ llc opt-pass.ll -o - .section __TEXT,__text,regular,pure_instructions .globl __ZN7WebCore6kolos1ERiS0_PKNS_20RenderBoxModelObjectEPNS_10StyleImageE .align 4, 0x90

This was set to zero immediately before the #GP injection code, since SYSENTER doesn''t really have a return address. Reported-by: Ian Campbell <Ian.Campbell@citrix.com> Furthermore, UREGS_cs and UREGS_rip don''t need to be written a second time, as the PUSHes above already can/do take care of putting in place the intended values. Signed-off-by: Jan Beulich

Hi, I'm working with workload where the bottleneck is cryptographic signature checks. Or, in compiler terms, most large integer operations. Looking at rL296252 , the state of affair in that area degraded quite significantly, see test/CodeGen/X86/i256-add.ll for instance. Is there some kind of work in progress here and it is expected to get better ? Because if not, that's a big problem.

I've been debugging a segfault issue with the elfreader and I would like to point out something that I have noticed. ELF.h declares an inline function, getElfArchType (MemoryBuffer *Object). When this function is called from ObjectFile::createELFObjectFile the pointer to Object was getting corrupted. The only thing that distinguished this pointer was that it was declared as a

On Wed, Oct 26, 2016 at 7:42 AM, Shi, Steven <steven.shi at intel.com> wrote: > Hi Kcc, > > I’m trying enabling the Asan in my firmware, but I find the asan > instrumentation code size impact is too big for me. I just implement > necessary firmware version runtime library functions (e.g. > __asan_report_load8) with blank body firstly to pass the asan enabled > build,

Hi Martin, Thank you for sending the script. I can reproduce the issue with it. It looks like the program crashes when it tries to call std::vector<sometype>'s ctor from a static initializer. I don't fully understand what is causing the issue yet, but here are my observations. - Since you are creating a temporary object file using `ld.gold -r`, your object file contains multiple

On Sep 1, 2010, at 6:25 AM, Argyrios Kyrtzidis wrote: > The attached .ll files seem equivalent, but the resulting asm from 'opt-fail.ll' causes a crash to webkit. > I suspect the usage of registers is wrong, can someone take a look ? The difference is that there is a shift right after the multiply, before the divide. In IR, the difference is: %5 = mul nsw i32 %4, %tmp1

On Sat, Jun 30, 2012 at 7:58 AM, Sid Manning <sidneym at codeaurora.org> wrote: > > I've been debugging a segfault issue with the elfreader and I would like to > point out something that I have noticed. > > ELF.h declares an inline function, getElfArchType (MemoryBuffer *Object). >  When this function is called from ObjectFile::createELFObjectFile the > pointer to

Change the assembly code to use only relative references of symbols for the kernel to be PIE compatible. Position Independent Executable (PIE) support will allow to extended the KASLR randomization range below the -2G memory limit. Signed-off-by: Thomas Garnier <thgarnie at google.com> --- arch/x86/kernel/acpi/wakeup_64.S | 31 ++++++++++++++++--------------- 1 file changed, 16

Compilers don't know about functions that are not defined in the same compilation unit, so they leave call instruction operands as zero (because they can't compute any absolute nor relative address of the destinations), and let linkers fix the address by binary patching. So, what you are seeing is likely a bug of LLD that it fails to fix the address for some reason. Can you dump that