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| author | Jakub Jelinek <jakub@redhat.com> | 2020-10-09 10:16:57 +0200 |
|---|---|---|
| committer | Jakub Jelinek <jakub@redhat.com> | 2020-10-09 10:18:41 +0200 |
| commit | 600cf1128e49f086522bfddc54490b4e39e30383 (patch) | |
| tree | 394041ef76ed7c8ba90598b84683260a69fae9dd /gcc/tree-ssa-loop-niter.c | |
| parent | 6887244269e0c412afd43474e13fa5ca12c350c4 (diff) | |
| download | gcc-600cf1128e49f086522bfddc54490b4e39e30383.zip gcc-600cf1128e49f086522bfddc54490b4e39e30383.tar.gz gcc-600cf1128e49f086522bfddc54490b4e39e30383.tar.bz2 | |
match.pd: Fix up FFS -> CTZ + 1 optimization [PR97325]
And no testcase was included, I'm including one below.
Anyway, this PR and the other CTZ related discussions led me to discover a
bug I've made earlier, CLZ/CTZ builtins have unsigned arguments and e.g.
both the vr-values.cc and now gimple-range.cc code heavily relies on that,
but __builtin_ffs has a signed operand and this optimization was incorrectly
making the operand signed too, so I guess it would greatly confuse VRP in
some cases.
2020-10-09 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/97325
* match.pd (FFS(nonzero) -> CTZ(nonzero) + 1): Cast argument to
corresponding unsigned type.
* gcc.c-torture/execute/pr97325.c: New test.
Diffstat (limited to 'gcc/tree-ssa-loop-niter.c')
0 files changed, 0 insertions, 0 deletions