Re: [PATCH, AArch64] Enable shrink wrap

[Sebastian Pop]

Marcus Shawcroft wrote:
> On 4 September 2014 15:14, Jiong Wang <jiong.w...@arm.com> wrote:
> > this patch enabled stack shrink-wrap support on AArch64.
> >
> > no regression on aarch64-none-elf bare-metal.
> > aarch64 bootstrap OK.
> >
> > ok to install?
> >
> > 2014-09-04 Renlin Li<renlin...@arm.com>
> >
> > gcc/
> >   * config/aarch64/aarch64.md (return): New expand.
> >   (simple_return): Likewise.
> >   * config/aarch64/aarch64.c (aarch64_use_return_insn_p): New function.
> >   * config/aarch64/aarch64-protos.h (aarch64_use_return_insn_p): New
> > declaration.
> >
> > gcc/testsuite
> >   * gcc.dg/ira-shrinkwrap-prep-1.c: Enable aarch64.
> >   * gcc.dg/ira-shrinkwrap-prep-2.c: Likewise.
> >   * gcc.dg/pr10474.c: Likewise.
> 
> OK, committed as 215508
> /Marcus

This patch causes a regression when compiling this testcase with -O2 and above:

void mm(double** A, double** B, double** C, unsigned N, unsigned S)
{
  unsigned i, j, k;

  for (i = 0; i < N; i += S) {
    for (j = 0; j < N; j += S) {
      for (k = 0; k < N; k += S) {

        unsigned ib = (N) < ((i + S)) ? N : (i + S);
        unsigned jb = (N) < ((j + S)) ? N : (j + S);
        unsigned kb = (N) < ((k + S)) ? N : (k + S);
        unsigned i0, j0, k0;

        for (i0 = i; i0 < ib; i0++) {
          for (j0 = j; j0 < jb; j0++) {
            double* a = A[i0];
            double* b = B[j0];
            double scratch = C[i0][j0];
            for (k0 = k; k0 < kb; k0++) {
              scratch += a[k0] * b[k0];
            }
            C[i0][j0] = scratch;
          }
        }
      }
    }
  }
  asm volatile ("bar:");
}

$ aarch64-gcc -O2 mm.c -S -o - | grep 'bar:' | wc -l
2
$ aarch64-gcc -O1 mm.c -S -o - | grep 'bar:' | wc -l
1

Thanks,
Sebastian