From a7b76d574b19190da190a60c065f347f40bab59e Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Wed, 6 May 2020 11:20:20 +0200 Subject: [PATCH] match.pd: Optimize ~(~X +- Y) into (X -+ Y) [PR94921] According to my verification proglet, this transformation for signed types with undefined overflow doesn't introduce nor remove any UB cases, so should be valid even for signed integral types. Not using a for because of the :c on plus which can't be there on minus. 2020-05-06 Jakub Jelinek PR tree-optimization/94921 * match.pd (~(~X - Y) -> X + Y, ~(~X + Y) -> X - Y): New simplifications. * gcc.dg/tree-ssa/pr94921.c: New test. --- gcc/ChangeLog | 6 ++++++ gcc/match.pd | 8 ++++++++ gcc/testsuite/ChangeLog | 4 ++++ gcc/testsuite/gcc.dg/tree-ssa/pr94921.c | 18 ++++++++++++++++++ 4 files changed, 36 insertions(+) create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr94921.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index e0dd54c..8bb2893 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2020-05-06 Jakub Jelinek + + PR tree-optimization/94921 + * match.pd (~(~X - Y) -> X + Y, ~(~X + Y) -> X - Y): New + simplifications. + 2020-05-06 Richard Biener PR tree-optimization/94965 diff --git a/gcc/match.pd b/gcc/match.pd index d957517..9259dd4 100644 --- a/gcc/match.pd +++ b/gcc/match.pd @@ -1010,6 +1010,14 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) @0)) #endif +/* ~(~X - Y) -> X + Y and ~(~X + Y) -> X - Y. */ +(simplify + (bit_not (minus (bit_not @0) @1)) + (plus @0 @1)) +(simplify + (bit_not (plus:c (bit_not @0) @1)) + (minus @0 @1)) + /* x + (x & 1) -> (x + 1) & ~1 */ (simplify (plus:c @0 (bit_and:s @0 integer_onep@1)) diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 1f01ff0..a66a012 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,5 +1,9 @@ 2020-05-06 Jakub Jelinek + PR tree-optimization/94921 + * match.pd (~(~X - Y) -> X + Y, ~(~X + Y) -> X - Y): New + simplifications. + PR rtl-optimization/94873 * gcc.dg/pr94873.c: New test. diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr94921.c b/gcc/testsuite/gcc.dg/tree-ssa/pr94921.c new file mode 100644 index 0000000..2c752ca --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr94921.c @@ -0,0 +1,18 @@ +/* PR tree-optimization/94921 */ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-optimized" } */ +/* { dg-final { scan-tree-dump " \[ab]_\[0-9]+\\\(D\\\) \\+ \[ab]_\[0-9]+\\\(D\\\);" "optimized" } } */ +/* { dg-final { scan-tree-dump " c_\[0-9]+\\\(D\\\) - d_\[0-9]+\\\(D\\\);" "optimized" } } */ +/* { dg-final { scan-tree-dump-not " ~\[abcd]\?_\[0-9]\+" "optimized" } } */ + +int +foo (int a, int b) +{ + return ~(~a - b); +} + +int +bar (int c, int d) +{ + return ~(~c + d); +} -- 2.7.4