[Bug c/40967] New: Bad Intel64 codegen for modified 39495 testcase

[brian dot e dot bliss at intel dot com]

Take the testcase for 39495, and add the "schedule(dynamic)" clause to the for
loop:

#include <stdlib.h>
#include <omp.h>

void foo(unsigned ub, unsigned *array)
{
    unsigned i;

// test passes for N >= 1
#define N       0

#pragma omp for schedule(dynamic)
    for (i = ub; i > N; i -=2) {
        array[i] = i;
    }
}

and compile with gcc -fopenmp -S.  Look at the way the parameters are set up
for the GOMP_loop_dynamic_start call:

movl    $1, %ecx
movl    $4294967294, %edx
movl    $0, %esi
movq    %rax, %rdi
call    GOMP_loop_dynamic_start

This looks like ia32 codegen to me - 1 is moved into %ecx, not %rcx, and 0 is
moved into %esi, not %rsi.  The harware zero extends the %e?x registers out to
64 bits (not sure if you can rely on that or if the extended bit values are
undefined), so that doesn't cause a failure.  What causes the full testcase to
crash is that moving 4294967294 into %edx causes %rdx = 0x00000000fffffffe, not
0xfffffffffffffffe = -2, the stride.  Whatever - it's obvious an ia32 code
fragment was selected instead of the intel64 version.


-- 
           Summary: Bad Intel64 codegen for modified 39495 testcase
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: brian dot e dot bliss at intel dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40967