[Bug middle-end/50397] New: openssl crash due to incorrect codegen when using LTO

["matt at use dot net" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50397

             Bug #: 50397
           Summary: openssl crash due to incorrect codegen when using LTO
    Classification: Unclassified
           Product: gcc
           Version: 4.6.2
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: matt@use.net


When adding -flto and compiling openssl-1.0.0d with gcc-4.6.real (Ubuntu/Linaro
4.6.1-9ubuntu2) that comes with Ubuntu 11.10, the testsuite fails with a
segfault during the bignumber tests. 

To reproduce:
1. untar openssl-1.0.0d
2. make this change in the Configure file on the "debian-amd64" line:
"debian-amd64", "gcc:-m64 -DL_ENDIAN -DTERMIO -O2 -flto -floop-block
-floop-flatten -floop-interchange -floop-strip-mine -Wa,--noexecstack -g -Wall
-DMD32_REG_T=int::-D_REENTRANT::-Wl,-flto=2 -ldl
-Wl,-Bsymbolic-functions:SIXTY_FOUR_BIT_LONG RC4_CHUNK DES_INT
DES_UNROLL:${x86_64_asm}:elf:dlfcn:linux-shared:-fPIC:-m64:.so.\$(SHLIB_MAJOR).\$(SHLIB_MINOR):::",

3. make, which will run the tests and fail.
4. for extra grins, run the specific suite under valgrind:
matt@matt-desktop:~/openssl-1.0.0d/test$ valgrind -q --trace-children=yes
../util/shlib_wrap.sh ./bntest
[...]
==12136== Process terminating with default action of signal 8 (SIGFPE)
==12136==  Integer divide by zero at address 0x40359EA94
==12136==    at 0x433C4D: BN_div (bn_div.c:342)
==12136==    by 0x403B86: main (bntest.c:1951)
Floating point exception (core dumped)


PS: I filed this as 4.6.2, given the number of patches that Linaro has applied
to this 4.6.1 base version. If that's wrong, let me know.
I tried testing it on trunk, but that gets an ICE during compile (filing a
separate bug).