[Bug middle-end/47522] New: [4.6 Regression] wrong code at -O3 -ffast-math

["Joost.VandeVondele at pci dot uzh.ch" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47522

           Summary: [4.6 Regression] wrong code at -O3 -ffast-math
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: Joost.VandeVondele@pci.uzh.ch


Created attachment 23157
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=23157
testcase, run under valgrind to see error

I'm seeing the following valgrind errors:

> valgrind ./a.out 
==4899== Memcheck, a memory error detector
==4899== Copyright (C) 2002-2009, and GNU GPL'd, by Julian Seward et al.
==4899== Using Valgrind-3.5.0 and LibVEX; rerun with -h for copyright info
==4899== Command: ./a.out
==4899== 
==4899== Invalid read of size 8
==4899==    at 0x402634: integrate_gf_npbc_ (in
/data03/vondele/cp2k_gcc/cp2k/src/a.out)
==4899==    by 0x4021B2: main (in /data03/vondele/cp2k_gcc/cp2k/src/a.out)
==4899==  Address 0x5b4ee40 is 0 bytes after a block of size 272 alloc'd
==4899==    at 0x4C26C3A: malloc (in
/usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==4899==    by 0x401A54: main (in /data03/vondele/cp2k_gcc/cp2k/src/a.out)
==4899== 


for the testcase compiled with 

> gfortran   -O3 -ffast-math  test.f90

this happens for current trunk, or more precisely:

> gfortran -v  -O3 -ffast-math  test.f90
Driving: gfortran -v -O3 -ffast-math test.f90 -l gfortran -l m -shared-libgcc
Using built-in specs.
COLLECT_GCC=gfortran
COLLECT_LTO_WRAPPER=/data03/vondele/gnu/gcc_trunk/install/libexec/gcc/x86_64-unknown-linux-gnu/4.6.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc/configure
--prefix=/data03/vondele/gnu/gcc_trunk/install --enable-languages=c,c++,fortran
--disable-multilib --enable-plugins --enable-cloog-backend=isl
--with-ppl=/data03/vondele/gnu/ppl-0.11/install
--with-cloog=/data03/vondele/gnu/cloog-0.16.1/install/
--with-libelf=/data03/vondele/gnu/libelf-0.8.13/install --enable-gold
--enable-checking=release
Thread model: posix
gcc version 4.6.0 20110128 (experimental) [trunk revision 169358] (GCC) 
COLLECT_GCC_OPTIONS='-v' '-O3' '-ffast-math' '-shared-libgcc' '-mtune=generic'
'-march=x86-64'

/data03/vondele/gnu/gcc_trunk/install/libexec/gcc/x86_64-unknown-linux-gnu/4.6.0/f951
test.f90 -quiet -dumpbase test.f90 -mtune=generic -march=x86-64 -auxbase test
-O3 -version -ffast-math -fintrinsic-modules-path
/data03/vondele/gnu/gcc_trunk/install/lib/gcc/x86_64-unknown-linux-gnu/4.6.0/finclude
-o /dev/shm/vondele/cc9gSh7M.s
GNU Fortran (GCC) version 4.6.0 20110128 (experimental) [trunk revision 169358]
(x86_64-unknown-linux-gnu)
        compiled by GNU C version 4.6.0 20110128 (experimental) [trunk revision
169358], GMP version 4.3.2, MPFR version 2.4.2, MPC version 0.8.2
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU Fortran (GCC) version 4.6.0 20110128 (experimental) [trunk revision 169358]
(x86_64-unknown-linux-gnu)
        compiled by GNU C version 4.6.0 20110128 (experimental) [trunk revision
169358], GMP version 4.3.2, MPFR version 2.4.2, MPC version 0.8.2
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
COLLECT_GCC_OPTIONS='-v' '-O3' '-ffast-math' '-shared-libgcc' '-mtune=generic'
'-march=x86-64'
 as --64 -o /dev/shm/vondele/ccpFdwCq.o /dev/shm/vondele/cc9gSh7M.s
Reading specs from
/data03/vondele/gnu/gcc_trunk/install/lib/gcc/x86_64-unknown-linux-gnu/4.6.0/../../../../lib64/libgfortran.spec
rename spec lib to liborig
COLLECT_GCC_OPTIONS='-v' '-O3' '-ffast-math' '-shared-libgcc' '-mtune=generic'
'-march=x86-64'
COMPILER_PATH=/data03/vondele/gnu/gcc_trunk/install/libexec/gcc/x86_64-unknown-linux-gnu/4.6.0/:/data03/vondele/gnu/gcc_trunk/install/libexec/gcc/x86_64-unknown-linux-gnu/4.6.0/:/data03/vondele/gnu/gcc_trunk/install/libexec/gcc/x86_64-unknown-linux-gnu/:/data03/vondele/gnu/gcc_trunk/install/lib/gcc/x86_64-unknown-linux-gnu/4.6.0/:/data03/vondele/gnu/gcc_trunk/install/lib/gcc/x86_64-unknown-linux-gnu/
LIBRARY_PATH=/data03/vondele/gnu/gcc_trunk/install/lib/gcc/x86_64-unknown-linux-gnu/4.6.0/:/data03/vondele/gnu/gcc_trunk/install/lib/gcc/x86_64-unknown-linux-gnu/4.6.0/../../../../lib64/:/lib/../lib64/:/usr/lib/../lib64/:/data03/vondele/gnu/gcc_trunk/install/lib/gcc/x86_64-unknown-linux-gnu/4.6.0/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-O3' '-ffast-math' '-shared-libgcc' '-mtune=generic'
'-march=x86-64'

/data03/vondele/gnu/gcc_trunk/install/libexec/gcc/x86_64-unknown-linux-gnu/4.6.0/collect2
--eh-frame-hdr -m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2
/usr/lib/../lib64/crt1.o /usr/lib/../lib64/crti.o
/data03/vondele/gnu/gcc_trunk/install/lib/gcc/x86_64-unknown-linux-gnu/4.6.0/crtbegin.o
-L/data03/vondele/gnu/gcc_trunk/install/lib/gcc/x86_64-unknown-linux-gnu/4.6.0
-L/data03/vondele/gnu/gcc_trunk/install/lib/gcc/x86_64-unknown-linux-gnu/4.6.0/../../../../lib64
-L/lib/../lib64 -L/usr/lib/../lib64
-L/data03/vondele/gnu/gcc_trunk/install/lib/gcc/x86_64-unknown-linux-gnu/4.6.0/../../..
/dev/shm/vondele/ccpFdwCq.o -lgfortran -lm -lgcc_s -lgcc -lquadmath -lm -lgcc_s
-lgcc -lc -lgcc_s -lgcc
/data03/vondele/gnu/gcc_trunk/install/lib/gcc/x86_64-unknown-linux-gnu/4.6.0/crtfastmath.o
/data03/vondele/gnu/gcc_trunk/install/lib/gcc/x86_64-unknown-linux-gnu/4.6.0/crtend.o
/usr/lib/../lib64/crtn.o
vondele@pcihopt3:/data03/vondele/cp2k_gcc/cp2k/src> gfortran   -O3 -ffast-math 
test.f90