[Bug middle-end/34725] New: [4.3 regression] gcc 4.3-rev 131213 miscompiles libgcrypt 1.4.0 at -O2 -mtune=i686 -fomit-frame-pointer

[bero at arklinux dot org]

Any application that uses libgcrypt 1.4.0 (including the parts of "make check"
in libgcrypt) segfaults if libgcrypt was built with gcc 4.3 (svn 131213) and
the CFLAGS setting includes "-O1 [or higher] -mtune=i686 -fomit-frame-pointer"

gdb shows the crash occurs in detect_ia32_gnuc() (defined in src/hwfeatures.c).

Adding a fprintf(stderr, "anything\n"); line anywhere in that function
(regardless where; done as part of locating the issue) makes the segfault go
away.

The segfault also doesn't occur if you just copy the code for
detect_ia32_gnuc() to a separate file and add a main() function calling it.


-- 
           Summary: [4.3 regression] gcc 4.3-rev 131213 miscompiles
                    libgcrypt 1.4.0 at -O2 -mtune=i686 -fomit-frame-pointer
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: bero at arklinux dot org
 GCC build triplet: i586-pc-linux-gnu
  GCC host triplet: i586-pc-linux-gnu
GCC target triplet: i586-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34725