diff options
| author | Richard Biener <rguenther@suse.de> | 2017-03-30 07:15:39 +0000 |
|---|---|---|
| committer | Richard Biener <rguenth@gcc.gnu.org> | 2017-03-30 07:15:39 +0000 |
| commit | 28c024077899ff4bad1fbce2d38fa8b5709272ef (patch) | |
| tree | 38df20abe28191bb91f3ec3d687054afe48af750 | |
| parent | e0aa80e05e24176051ef644856dd25784344308a (diff) | |
| download | gcc-28c024077899ff4bad1fbce2d38fa8b5709272ef.zip gcc-28c024077899ff4bad1fbce2d38fa8b5709272ef.tar.gz gcc-28c024077899ff4bad1fbce2d38fa8b5709272ef.tar.bz2 | |
re PR tree-optimization/77498 (Performance drop after r239414 on spec2000/172mgrid)
2017-03-30 Richard Biener <rguenther@suse.de>
PR tree-optimization/77498
* tree-ssa-pre.c (phi_translate_1): Do not allow simplifications
to non-constants over backedges.
* gfortran.dg/pr77498.f: New testcase.
From-SVN: r246583
| -rw-r--r-- | gcc/ChangeLog | 6 | ||||
| -rw-r--r-- | gcc/testsuite/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/testsuite/gfortran.dg/pr77498.f | 36 | ||||
| -rw-r--r-- | gcc/tree-ssa-pre.c | 18 |
4 files changed, 61 insertions, 4 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 85b1c37..3333bfd 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2017-03-30 Richard Biener <rguenther@suse.de> + + PR tree-optimization/77498 + * tree-ssa-pre.c (phi_translate_1): Do not allow simplifications + to non-constants over backedges. + 2017-03-29 Segher Boessenkool <segher@kernel.crashing.org> PR rtl-optimization/80233 diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index d8e6f87..5d33ce7 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2017-03-30 Richard Biener <rguenther@suse.de> + + PR tree-optimization/77498 + * gfortran.dg/pr77498.f: New testcase. + 2017-03-29 Marek Polacek <polacek@redhat.com> PR c/79730 diff --git a/gcc/testsuite/gfortran.dg/pr77498.f b/gcc/testsuite/gfortran.dg/pr77498.f new file mode 100644 index 0000000..f957b57 --- /dev/null +++ b/gcc/testsuite/gfortran.dg/pr77498.f @@ -0,0 +1,36 @@ +! { dg-do compile } +! { dg-options "-O2 -ffast-math -fdump-tree-pre" } + + subroutine foo(U,V,R,N,A) + integer N + real*8 U(N,N,N),V(N,N,N),R(N,N,N),A(0:3) + integer I3, I2, I1 +C + do I3=2,N-1 + do I2=2,N-1 + do I1=2,N-1 + R(I1,I2,I3)=V(I1,I2,I3) + * -A(0)*( U(I1, I2, I3 ) ) + * -A(1)*( U(I1-1,I2, I3 ) + U(I1+1,I2, I3 ) + * + U(I1, I2-1,I3 ) + U(I1, I2+1,I3 ) + * + U(I1, I2, I3-1) + U(I1, I2, I3+1) ) + * -A(2)*( U(I1-1,I2-1,I3 ) + U(I1+1,I2-1,I3 ) + * + U(I1-1,I2+1,I3 ) + U(I1+1,I2+1,I3 ) + * + U(I1, I2-1,I3-1) + U(I1, I2+1,I3-1) + * + U(I1, I2-1,I3+1) + U(I1, I2+1,I3+1) + * + U(I1-1,I2, I3-1) + U(I1-1,I2, I3+1) + * + U(I1+1,I2, I3-1) + U(I1+1,I2, I3+1) ) + * -A(3)*( U(I1-1,I2-1,I3-1) + U(I1+1,I2-1,I3-1) + * + U(I1-1,I2+1,I3-1) + U(I1+1,I2+1,I3-1) + * + U(I1-1,I2-1,I3+1) + U(I1+1,I2-1,I3+1) + * + U(I1-1,I2+1,I3+1) + U(I1+1,I2+1,I3+1) ) + enddo + enddo + enddo + return + end + +! PRE shouldn't do predictive commonings job here (and in a bad way) +! ??? It still does but not as bad as it could. Less prephitmps +! would be better, pcom does it with 6. +! { dg-final { scan-tree-dump-times "# prephitmp" 9 "pre" } } diff --git a/gcc/tree-ssa-pre.c b/gcc/tree-ssa-pre.c index ff59d53..c6aa587 100644 --- a/gcc/tree-ssa-pre.c +++ b/gcc/tree-ssa-pre.c @@ -1468,10 +1468,20 @@ phi_translate_1 (pre_expr expr, bitmap_set_t set1, bitmap_set_t set2, leader for it. */ if (constant->kind != CONSTANT) { - unsigned value_id = get_expr_value_id (constant); - constant = find_leader_in_sets (value_id, set1, set2); - if (constant) - return constant; + /* Do not allow simplifications to non-constants over + backedges as this will likely result in a loop PHI node + to be inserted and increased register pressure. + See PR77498 - this avoids doing predcoms work in + a less efficient way. */ + if (find_edge (pred, phiblock)->flags & EDGE_DFS_BACK) + ; + else + { + unsigned value_id = get_expr_value_id (constant); + constant = find_leader_in_sets (value_id, set1, set2); + if (constant) + return constant; + } } else return constant; |