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| author | Andrew Pinski <apinski@marvell.com> | 2021-11-13 04:16:55 +0000 |
|---|---|---|
| committer | Andrew Pinski <apinski@marvell.com> | 2021-11-16 15:07:39 +0000 |
| commit | 11c4a06a6c1a9db0bfdb3ee8509392dd7163709c (patch) | |
| tree | 80270fb57c185187dd247904448330e62acadb8b | |
| parent | 8d8e8f3ad567c7bd1de708fcc841f691d9686c4d (diff) | |
| download | gcc-11c4a06a6c1a9db0bfdb3ee8509392dd7163709c.zip gcc-11c4a06a6c1a9db0bfdb3ee8509392dd7163709c.tar.gz gcc-11c4a06a6c1a9db0bfdb3ee8509392dd7163709c.tar.bz2 | |
tree-optimization: [PR103218] Fold ((type)(a<0)) << SIGNBITOFA into ((type)a) & signbit
This folds Fold ((type)(a<0)) << SIGNBITOFA into ((type)a) & signbit inside match.pd.
This was already handled in fold-cost by:
/* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
I have not removed as we only simplify "a ? POW2 : 0" at the gimple level to "a << CST1"
and fold actually does the reverse of folding "(a<0)<<CST" into "(a<0) ? 1<<CST : 0".
OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.
PR tree-optimization/103218
gcc/ChangeLog:
* match.pd: New pattern for "((type)(a<0)) << SIGNBITOFA".
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/pr103218-1.c: New test.
| -rw-r--r-- | gcc/match.pd | 10 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.dg/tree-ssa/pr103218-1.c | 28 |
2 files changed, 38 insertions, 0 deletions
diff --git a/gcc/match.pd b/gcc/match.pd index 758322d..7f76925 100644 --- a/gcc/match.pd +++ b/gcc/match.pd @@ -865,6 +865,16 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) { tree utype = unsigned_type_for (type); } (convert (rshift (lshift (convert:utype @0) @2) @3)))))) +/* Fold ((type)(a<0)) << SIGNBITOFA into ((type)a) & signbit. */ +(simplify + (lshift (convert (lt @0 integer_zerop@1)) INTEGER_CST@2) + (if (TYPE_SIGN (TREE_TYPE (@0)) == SIGNED + && wi::eq_p (wi::to_wide (@2), TYPE_PRECISION (TREE_TYPE (@0)) - 1)) + (with { wide_int wone = wi::one (TYPE_PRECISION (type)); } + (bit_and (convert @0) + { wide_int_to_tree (type, + wi::lshift (wone, wi::to_wide (@2))); })))) + /* Fold (-x >> C) into -(x > 0) where C = precision(type) - 1. */ (for cst (INTEGER_CST VECTOR_CST) (simplify diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr103218-1.c b/gcc/testsuite/gcc.dg/tree-ssa/pr103218-1.c new file mode 100644 index 0000000..f086f07 --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr103218-1.c @@ -0,0 +1,28 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-optimized" } */ +/* PR tree-optimization/103218 */ + +/* These first two are removed during forwprop1 */ +signed char f(signed char a) +{ + signed char t = a < 0; + int tt = (unsigned char)(t << 7); + return tt; +} +signed char f0(signed char a) +{ + unsigned char t = a < 0; + int tt = (unsigned char)(t << 7); + return tt; +} + +/* This one is removed during phiopt. */ +signed char f1(signed char a) +{ + if (a < 0) + return 1u<<7; + return 0; +} + +/* These three examples should remove "a < 0" by optimized. */ +/* { dg-final { scan-tree-dump-times "< 0" 0 "optimized"} } */ |