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| author | Jakub Jelinek <jakub@redhat.com> | 2021-01-15 21:10:44 +0100 |
|---|---|---|
| committer | Jakub Jelinek <jakub@redhat.com> | 2021-01-15 21:10:44 +0100 |
| commit | 5c046034e3ea61dd68965154a398f8f813daf8f2 (patch) | |
| tree | 3bd073451c69e3dbb6f9eff9dac0a17f6f6d0e49 /gcc/match.pd | |
| parent | e63c2161d09903ca5c07b1eb0d8c0a1a17967499 (diff) | |
| download | gcc-5c046034e3ea61dd68965154a398f8f813daf8f2.zip gcc-5c046034e3ea61dd68965154a398f8f813daf8f2.tar.gz gcc-5c046034e3ea61dd68965154a398f8f813daf8f2.tar.bz2 | |
match.pd: Optimize (x < 0) ^ (y < 0) to (x ^ y) < 0 etc. [PR96681]
This patch simplifies comparisons that test the sign bit xored together.
If the comparisons are both < 0 or both >= 0, then we should xor the operands
together and compare the result to < 0, if the comparisons are different,
we should compare to >= 0.
2021-01-15 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/96681
* match.pd ((x < 0) ^ (y < 0) to (x ^ y) < 0): New simplification.
((x >= 0) ^ (y >= 0) to (x ^ y) < 0): Likewise.
((x < 0) ^ (y >= 0) to (x ^ y) >= 0): Likewise.
((x >= 0) ^ (y < 0) to (x ^ y) >= 0): Likewise.
* gcc.dg/tree-ssa/pr96681.c: New test.
Diffstat (limited to 'gcc/match.pd')
| -rw-r--r-- | gcc/match.pd | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/gcc/match.pd b/gcc/match.pd index f08ab67..e731bdb 100644 --- a/gcc/match.pd +++ b/gcc/match.pd @@ -3993,6 +3993,24 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) (if (single_use (@2)) (cmp @0 @1))))) +/* Simplify (x < 0) ^ (y < 0) to (x ^ y) < 0 and + (x >= 0) ^ (y >= 0) to (x ^ y) < 0. */ +(for cmp (lt ge) + (simplify + (bit_xor (cmp:s @0 integer_zerop) (cmp:s @1 integer_zerop)) + (if (INTEGRAL_TYPE_P (TREE_TYPE (@0)) + && !TYPE_UNSIGNED (TREE_TYPE (@0)) + && types_match (TREE_TYPE (@0), TREE_TYPE (@1))) + (lt (bit_xor @0 @1) { build_zero_cst (TREE_TYPE (@0)); })))) +/* Simplify (x < 0) ^ (y >= 0) to (x ^ y) >= 0 and + (x >= 0) ^ (y < 0) to (x ^ y) >= 0. */ +(simplify + (bit_xor:c (lt:s @0 integer_zerop) (ge:s @1 integer_zerop)) + (if (INTEGRAL_TYPE_P (TREE_TYPE (@0)) + && !TYPE_UNSIGNED (TREE_TYPE (@0)) + && types_match (TREE_TYPE (@0), TREE_TYPE (@1))) + (ge (bit_xor @0 @1) { build_zero_cst (TREE_TYPE (@0)); }))) + /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the signed arithmetic case. That form is created by the compiler often enough for folding it to be of value. One example is in |