Hi!
Those 2 checks were just me trying to be extra careful, the
(phires & 1) == phires and variants it is folded to of course make only sense
for the -1/0/1/2 result spaceship, for -1/0/1 one can just use comparisons of
phires. We only floating point spaceship if nans aren't honored, so the
2 case is ignored, and if it is, with Aldy's changes we can simplify the
2 case away from the phi but the (phires & 1) == phires stayed. It is safe
to treat the phires comparison as phires >= 0 even then.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2022-08-11 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/106506
* tree-ssa-phiopt.cc (spaceship_replacement): Don't punt for
is_cast or orig_use_lhs cases if phi_bb has 3 predecessors.
* g++.dg/opt/pr94589-2.C: New test.
--- gcc/tree-ssa-phiopt.cc.jj 2022-08-10 09:06:53.000000000 +0200
+++ gcc/tree-ssa-phiopt.cc 2022-08-10 15:33:32.414641593 +0200
@@ -2448,8 +2448,6 @@ spaceship_replacement (basic_block cond_
return false;
if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (orig_use_lhs))
return false;
- if (EDGE_COUNT (phi_bb->preds) != 4)
- return false;
if (!single_imm_use (orig_use_lhs, &use_p, &use_stmt))
return false;
@@ -2467,8 +2465,6 @@ spaceship_replacement (basic_block cond_
orig_use_lhs = gimple_assign_lhs (use_stmt);
if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (orig_use_lhs))
return false;
- if (EDGE_COUNT (phi_bb->preds) != 4)
- return false;
if (!single_imm_use (orig_use_lhs, &use_p, &use_stmt))
return false;
}
--- gcc/testsuite/g++.dg/opt/pr94589-2.C.jj 2022-08-10 09:06:52.921213966
+0200
+++ gcc/testsuite/g++.dg/opt/pr94589-2.C 2022-08-10 15:45:24.599319922
+0200
@@ -1,7 +1,7 @@
// PR tree-optimization/94589
// { dg-do compile { target c++20 } }
// { dg-options "-O2 -g0 -ffast-math -fdump-tree-optimized" }
-// { dg-final { scan-tree-dump-times "\[ij]_\[0-9]+\\(D\\) (?:<|<=|==|!=|>|>=)
\[ij]_\[0-9]+\\(D\\)" 12 "optimized" { xfail *-*-* } } }
+// { dg-final { scan-tree-dump-times "\[ij]_\[0-9]+\\(D\\) (?:<|<=|==|!=|>|>=)
\[ij]_\[0-9]+\\(D\\)" 12 "optimized" } }
// { dg-final { scan-tree-dump-times "i_\[0-9]+\\(D\\) (?:<|<=|==|!=|>|>=)
5\\.0" 12 "optimized" } }
#include <compare>
Jakub
