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| author | Jakub Jelinek <jakub@redhat.com> | 2020-12-31 11:09:26 +0100 |
|---|---|---|
| committer | Jakub Jelinek <jakub@redhat.com> | 2020-12-31 11:09:26 +0100 |
| commit | d2eb616a0f7bea78164912aa438c29fe1ef5774a (patch) | |
| tree | e8a936a3ca8918db0ea67a25b389229d551e53b8 /gcc/match.pd | |
| parent | 8f12ce2ea3be12de4f83d3c419bdb1dc5036b202 (diff) | |
| download | gcc-d2eb616a0f7bea78164912aa438c29fe1ef5774a.zip gcc-d2eb616a0f7bea78164912aa438c29fe1ef5774a.tar.gz gcc-d2eb616a0f7bea78164912aa438c29fe1ef5774a.tar.bz2 | |
match.pd: Add clz(X) == 0 -> (int)X < 0 etc. simpifications [PR94802]
The following patch adds some clz simplifications. If
clz is 0, then the MSB of the argument is set, and if clz is prec-1, then
the argument is 1.
2020-12-31 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/94802
* match.pd (clz(X) == 0 -> (int)X < 0): New simplification.
(clz(X) == (prec-1) -> X == 1): Likewise.
* gcc.dg/tree-ssa/pr94802-1.c: New test.
Diffstat (limited to 'gcc/match.pd')
| -rw-r--r-- | gcc/match.pd | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/gcc/match.pd b/gcc/match.pd index 1055292..529933f 100644 --- a/gcc/match.pd +++ b/gcc/match.pd @@ -6226,6 +6226,39 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) (if (single_use (@3)) (IFN_FMA @0 @1 @2)))) +/* CLZ simplifications. */ +(for clz (CLZ) + (for op (eq ne) + cmp (lt ge) + (simplify + (op (clz:s @0) INTEGER_CST@1) + (if (integer_zerop (@1)) + /* clz(X) == 0 is (int)X < 0 and clz(X) != 0 is (int)X >= 0. */ + (with { tree stype = signed_type_for (TREE_TYPE (@0)); + HOST_WIDE_INT val = 0; +#ifdef CLZ_DEFINED_VALUE_AT_ZERO + /* Punt on hypothetical weird targets. */ + if (CLZ_DEFINED_VALUE_AT_ZERO (TYPE_MODE (TREE_TYPE (@0)), + val) == 2 + && val == 0) + stype = NULL_TREE; +#endif + } + (if (stype) + (cmp (convert:stype @0) { build_zero_cst (stype); }))) + /* clz(X) == (prec-1) is X == 1 and clz(X) != (prec-1) is X != 1. */ + (with { bool ok = true; +#ifdef CLZ_DEFINED_VALUE_AT_ZERO + /* Punt on hypothetical weird targets. */ + if (CLZ_DEFINED_VALUE_AT_ZERO (TYPE_MODE (TREE_TYPE (@0)), + val) == 2 + && val == TYPE_PRECISION (TREE_TYPE (@0)) - 1) + ok = false; +#endif + } + (if (ok && wi::to_wide (@1) == (TYPE_PRECISION (TREE_TYPE (@0)) - 1)) + (op @0 { build_one_cst (TREE_TYPE (@0)); }))))))) + /* POPCOUNT simplifications. */ /* popcount(X) + popcount(Y) is popcount(X|Y) when X&Y must be zero. */ (simplify |