> gcc version 4.1.0-gomp-20050608-branch 20051109 (experimental) (merged
20051109)

BTW, it appears as if the compiler datestamp is not correctly updated on
the gomp branch (it says 20051109, but there have been commits to the branch
after that date).

The problem here is a mismatch between determine_parallel_type in gimplify.c
and omp-low.c.  During gimplification, it is not considered to be a combined
parallel loop, because OMP_PARALLEL's body contains a DECL_EXPR (for m variable)
before OMP_FOR.  But during omp lowering, that DECL_EXPR is already gone and
therefore the loop is handled as a combined loop.  But there are statements
before the FOR_STMT inside of OMP_FOR, and those are moved into a wrong context
when doing a parallel loop.
Maybe we should ignore (some?) DECL_EXPRs in determine_parallel_type, maybe
we need to note the combined parallel status in OMP_PARALLEL's flags.

Some more information:

- I didn't encounter the bug about a week ago
- on x86_64 with checking disabled, I get

guest@mpac-7:~/martin> g++ -c -v -fopenmp test.cc
Using built-in specs.
Target: x86_64-unknown-linux-gnu
Configured with: /home/guest/martin/gompcc/configure --quiet --prefix=/home/guest/martin/ugccgomp --disable-checking --enable-languages=c++,fortran --with-gmp=/home/guest/martin/mygmp
Thread model: posix
gcc version 4.1.0-gomp-20050608-branch 20051109 (experimental) (merged 20051109)
 /home/guest/martin/ugccgomp/libexec/gcc/x86_64-unknown-linux-gnu/4.1.0-gomp-20050608-branch/cc1plus -quiet -v -D_GNU_SOURCE test.cc -quiet -dumpbase test.cc -mtune=k8 -auxbase test -version -fopenmp -o /tmp/ccH4pPJ3.s
ignoring nonexistent directory "/home/guest/martin/ugccgomp/lib/gcc/x86_64-unknown-linux-gnu/4.1.0-gomp-20050608-branch/../../../../x86_64-unknown-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /home/guest/martin/ugccgomp/lib/gcc/x86_64-unknown-linux-gnu/4.1.0-gomp-20050608-branch/../../../../include/c++/4.1.0-gomp-20050608-branch
 /home/guest/martin/ugccgomp/lib/gcc/x86_64-unknown-linux-gnu/4.1.0-gomp-20050608-branch/../../../../include/c++/4.1.0-gomp-20050608-branch/x86_64-unknown-linux-gnu
 /home/guest/martin/ugccgomp/lib/gcc/x86_64-unknown-linux-gnu/4.1.0-gomp-20050608-branch/../../../../include/c++/4.1.0-gomp-20050608-branch/backward
 /usr/local/include
 /home/guest/martin/ugccgomp/include
 /home/guest/martin/ugccgomp/lib/gcc/x86_64-unknown-linux-gnu/4.1.0-gomp-20050608-branch/include
 /usr/include
End of search list.
GNU C++ version 4.1.0-gomp-20050608-branch 20051109 (experimental) (merged 20051109) (x86_64-unknown-linux-gnu)
        compiled by GNU C version 4.1.0-gomp-20050608-branch 20051109 (experimental) (merged 20051109).
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 77b131b8a7d189e4ba7ca911c1f9b018
test.cc: In member function â:
test.cc:10: error: insn does not satisfy its constraints:
(insn 14 13 38 (set (reg:DI 0 ax [orig:58 D.2187 ] [58])
        (sign_extend:DI (reg:SI 77 [ D.2153 ]))) 115 {extendsidi2_rex64} (nil)
    (nil))
test.cc:10: internal compiler error: in extract_constrain_insn_cached, at recog.c:2002
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://gcc.gnu.org/bugs.html> for instructions.

Working on this.

Here's a shorter testcase without templates:

==========================================
void foo()
{
#pragma omp parallel
    {
        int i, N;
#pragma omp for schedule (dynamic)
        for (i=0; i<N; ++i) ;
    }
}
==========================================

The bug only affects the C++ frontend.
The above testcase compiles fine with the C frontend.

Subject: Bug 24849

Author: dnovillo
Date: Sat Nov 19 15:18:08 2005
New Revision: 107220

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=107220
Log:

	PR 24849
	* omp-low.c (determine_parallel_type): Do not handle OMP_FOR.

testsuite/

	PR 24849
	* g++.dg/gomp/pr24849.C: New test.
	* gcc.dg/gomp/for-19.c: XFAIL.
	* gcc.dg/gomp/for-18.c: XFAIL.


Added:
    branches/gomp-20050608-branch/gcc/testsuite/g++.dg/gomp/pr24849.C
Modified:
    branches/gomp-20050608-branch/gcc/ChangeLog.gomp
    branches/gomp-20050608-branch/gcc/omp-low.c
    branches/gomp-20050608-branch/gcc/testsuite/ChangeLog.gomp
    branches/gomp-20050608-branch/gcc/testsuite/gcc.dg/gomp/for-18.c
    branches/gomp-20050608-branch/gcc/testsuite/gcc.dg/gomp/for-19.c

Workaround applied.

The actual solution separates lowering from optimization, once all the OMP directives are lowered to a language-independent form, we can apply the combined parallel+loop optimization without running into these odd corners.

I need a few more days to finish implementing this separation.  In the meantime, we can live without this optimization.