Currently we able to simplify `~a CMP ~b` to `b CMP a` but we should allow a nop conversion in between the `~` and the `a` which can show up. A similarly thing should be done for `~a CMP CST`.
I had originally submitted the `~a CMP CST` case as https://gcc.gnu.org/pipermail/gcc-patches/2021-November/585088.html; I noticed we should do the same thing for the `~a CMP ~b` case and combined it with that one here. OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions. PR tree-optimization/31531 gcc/ChangeLog: * match.pd (~X op ~Y): Allow for an optional nop convert. (~X op C): Likewise. gcc/testsuite/ChangeLog: * gcc.dg/tree-ssa/pr31531-1.c: New test. * gcc.dg/tree-ssa/pr31531-2.c: New test. --- gcc/match.pd | 10 ++++--- gcc/testsuite/gcc.dg/tree-ssa/pr31531-1.c | 19 +++++++++++++ gcc/testsuite/gcc.dg/tree-ssa/pr31531-2.c | 34 +++++++++++++++++++++++ 3 files changed, 59 insertions(+), 4 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr31531-1.c create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr31531-2.c diff --git a/gcc/match.pd b/gcc/match.pd index 51e5065d086..e76ec1ec034 100644 --- a/gcc/match.pd +++ b/gcc/match.pd @@ -5944,18 +5944,20 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) /* Fold ~X op ~Y as Y op X. */ (for cmp (simple_comparison) (simplify - (cmp (bit_not@2 @0) (bit_not@3 @1)) + (cmp (nop_convert1?@4 (bit_not@2 @0)) (nop_convert2? (bit_not@3 @1))) (if (single_use (@2) && single_use (@3)) - (cmp @1 @0)))) + (with { tree otype = TREE_TYPE (@4); } + (cmp (convert:otype @1) (convert:otype @0)))))) /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */ (for cmp (simple_comparison) scmp (swapped_simple_comparison) (simplify - (cmp (bit_not@2 @0) CONSTANT_CLASS_P@1) + (cmp (nop_convert? (bit_not@2 @0)) CONSTANT_CLASS_P@1) (if (single_use (@2) && (TREE_CODE (@1) == INTEGER_CST || TREE_CODE (@1) == VECTOR_CST)) - (scmp @0 (bit_not @1))))) + (with { tree otype = TREE_TYPE (@1); } + (scmp (convert:otype @0) (bit_not @1)))))) (for cmp (simple_comparison) (simplify diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr31531-1.c b/gcc/testsuite/gcc.dg/tree-ssa/pr31531-1.c new file mode 100644 index 00000000000..c27299151eb --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr31531-1.c @@ -0,0 +1,19 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-optimized" } */ +/* PR tree-optimization/31531 */ + +int f(int a) +{ + int b = ~a; + return b<0; +} + + +int f1(unsigned a) +{ + int b = ~a; + return b<0; +} +/* We should convert the above two functions from b <0 to ((int)a) >= 0. */ +/* { dg-final { scan-tree-dump-times ">= 0" 2 "optimized"} } */ +/* { dg-final { scan-tree-dump-times "~" 0 "optimized"} } */ diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr31531-2.c b/gcc/testsuite/gcc.dg/tree-ssa/pr31531-2.c new file mode 100644 index 00000000000..865ea292215 --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr31531-2.c @@ -0,0 +1,34 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-optimized" } */ +/* PR tree-optimization/31531 */ + +int f0(unsigned x, unsigned t) +{ + x = ~x; + t = ~t; + int xx = x; + int tt = t; + return tt < xx; +} + +int f1(unsigned x, int t) +{ + x = ~x; + t = ~t; + int xx = x; + int tt = t; + return tt < xx; +} + +int f2(int x, unsigned t) +{ + x = ~x; + t = ~t; + int xx = x; + int tt = t; + return tt < xx; +} + + +/* We should be able to remove all ~ from the above functions. */ +/* { dg-final { scan-tree-dump-times "~" 0 "optimized"} } */ -- 2.39.3
