https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77996
Richard Earnshaw changed:
What|Removed |Added
Status|WAITING |RESOLVED
Resolution|---
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77996
--- Comment #12 from Yichao Yu ---
Since the LLVM miscompilation isn't fixed, is there any way to check the alias
assumptions more programmatically? (I can see that the TrailingObject might
easily introduce something like this but given the
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77996
--- Comment #11 from Yichao Yu ---
The case pointed out is fixed in https://reviews.llvm.org/rL284336 although as
expected that doesn't fix the error. Still not sure whose bug is this...
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77996
--- Comment #10 from Yichao Yu ---
That does look like an violation (this particular one should be hidden behind
shared library boundary in the reduced case though). Reported to LLVM at
https://llvm.org/bugs/show_bug.cgi?id=30711 .
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77996
--- Comment #9 from Andrew Pinski ---
here is one example where LLVM could be violating C aliasing rules:
void FoldingSetNodeID::AddPointer(const void *Ptr) {
Bits.append(reinterpret_cast(),
reinterpret_cast(+1));
}
There could
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77996
--- Comment #8 from Yichao Yu ---
> Can you try with -fno-strict-aliasing ?
That seems to fix it for both the original case (LLVM) and the reduced case
(the linked tarball). Is there a way to figure out the problematic (either bug
in LLVM's
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77996
--- Comment #7 from Andrew Pinski ---
Can you try with -fno-strict-aliasing ?
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77996
--- Comment #6 from Yichao Yu ---
I've compiled a gcc at 951db45 using the same configuration as archlinux arm
PKGBUILD and I can reproduce the problem using the `code/` in
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77996
--- Comment #5 from Yichao Yu ---
Compiling current llvm trunk (r284322) still shows the same error. The script I
used to compile LLVM is here
https://github.com/yuyichao/arch-pkg/blob/master/pkg/all/llvm-svn/PKGBUILD.
Compiling gcc 951db45
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77996
--- Comment #4 from Andrew Pinski ---
# Arch Linux installs 64bit libraries /lib
So non-standard (but that is not an issue here).
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77996
--- Comment #3 from Yichao Yu ---
> What exact version of LLVM are you trying to compile? Revision of the LLVM
> sources including revision of clang, etc.
I was compiling the trunk version. The version I started reducing from was
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77996
--- Comment #2 from Andrew Pinski ---
*** Bug 77997 has been marked as a duplicate of this bug. ***
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