[Bug tree-optimization/49140] New: [4.6 regression] wrong code with -O2 and -O3, not with -O3 -no-inline

["doko at ubuntu dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49140

           Summary: [4.6 regression] wrong code with -O2 and -O3, not with
                    -O3 -no-inline
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: doko@ubuntu.com


Created attachment 24342
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=24342
preprocessed source

[forwarded from http://bugs.debian.org/627084]

seen with r174102 from the 4.6 branch, works with r173903 from the trunk


Step to reproduce:

wget 'http://pari.math.u-bordeaux.fr/~bill/pari-2.4.3.12000.tar.gz'
tar xf pari-2.4.3.12000.tar.gz
cd pari-2.4.3.alpha
./Configure
make gp
make bench

Result: all test suite fail.

Cause: 

The function pari_init_parser() in the file src/language/parsec.h is
miscompiled.
(This file is included by src/language/parse.y).

If you replace the line 43: s_node.n=OPnboperator; by parsestate_reset(); 
(which does the same thing), then all test pass.

It seems that the issue is that the function stack_alloc() is not inlined
correctly,
which cause pari_tree to be NULL (or maybe the call to pari_inline inside
stack_alloc()
is not inlined correctly.

The command line used is
gcc-4.6  -c -O3 -Wall -fno-strict-aliasing -fomit-frame-pointer    -I.
-I../src/headers -fPIC -o
parse.o ../src/language/parse.c

It also happens with -O2, but not with -O3 -fno-inline.

It works fine with gcc 4.3, 4.4 and 4.5.