Previous revision here: https://gcc.gnu.org/ml/gcc-patches/2017-07/msg01090.html
Reassociate X * CST1 * CST2 to X * (CST1 * CST2). Changed in this revision: - remove the check for @2 being 0 or -1 * match.pd ((X * CST1) * CST2): Simplify to X * (CST1 * CST2). testsuite: * gcc.dg/tree-ssa/assoc-2.c: Enhance. * gcc.dg/tree-ssa/slsr-4.c: Adjust. --- gcc/match.pd | 13 +++++++++++++ gcc/testsuite/gcc.dg/tree-ssa/assoc-2.c | 13 ++++++++++++- gcc/testsuite/gcc.dg/tree-ssa/slsr-4.c | 8 ++------ 3 files changed, 27 insertions(+), 7 deletions(-) diff --git a/gcc/match.pd b/gcc/match.pd index 39e1e5c..732b80c 100644 --- a/gcc/match.pd +++ b/gcc/match.pd @@ -284,6 +284,19 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) || mul != wi::min_value (TYPE_PRECISION (type), SIGNED)) { build_zero_cst (type); }))))) +/* Combine successive multiplications. Similar to above, but handling + overflow is different. */ +(simplify + (mult (mult @0 INTEGER_CST@1) INTEGER_CST@2) + (with { + bool overflow_p; + wide_int mul = wi::mul (@1, @2, TYPE_SIGN (type), &overflow_p); + } + /* Skip folding on overflow: the only special case is @1 * @2 == -INT_MIN, + otherwise undefined overflow implies that @0 must be zero. */ + (if (!overflow_p || TYPE_OVERFLOW_WRAPS (type)) + (mult @0 { wide_int_to_tree (type, mul); })))) + /* Optimize A / A to 1.0 if we don't care about NaNs or Infinities. */ (simplify diff --git a/gcc/testsuite/gcc.dg/tree-ssa/assoc-2.c b/gcc/testsuite/gcc.dg/tree-ssa/assoc-2.c index a92c882..cc0e9d4 100644 --- a/gcc/testsuite/gcc.dg/tree-ssa/assoc-2.c +++ b/gcc/testsuite/gcc.dg/tree-ssa/assoc-2.c @@ -5,4 +5,15 @@ int f0(int a, int b){ return a * 33 * b * 55; } -/* { dg-final { scan-tree-dump-times "mult_expr" 2 "gimple" } } */ +int f1(int a){ + a *= 33; + return a * 55; +} + +int f2(int a, int b){ + a *= 33; + return a * b * 55; +} + +/* { dg-final { scan-tree-dump-times "mult_expr" 7 "gimple" } } */ +/* { dg-final { scan-tree-dump-times "mult_expr" 5 "optimized" } } */ diff --git a/gcc/testsuite/gcc.dg/tree-ssa/slsr-4.c b/gcc/testsuite/gcc.dg/tree-ssa/slsr-4.c index 17d7b4c..1e943b7 100644 --- a/gcc/testsuite/gcc.dg/tree-ssa/slsr-4.c +++ b/gcc/testsuite/gcc.dg/tree-ssa/slsr-4.c @@ -23,13 +23,9 @@ f (int i) foo (y); } -/* { dg-final { scan-tree-dump-times "\\* 4" 1 "slsr" } } */ -/* { dg-final { scan-tree-dump-times "\\* 10" 1 "slsr" } } */ -/* { dg-final { scan-tree-dump-times "\\+ 20;" 1 "slsr" } } */ +/* { dg-final { scan-tree-dump-times "\\* 40" 1 "slsr" } } */ /* { dg-final { scan-tree-dump-times "\\+ 200" 1 "slsr" } } */ -/* { dg-final { scan-tree-dump-times "\\- 16;" 1 "slsr" } } */ /* { dg-final { scan-tree-dump-times "\\- 160" 1 "slsr" } } */ -/* { dg-final { scan-tree-dump-times "\\* 4" 1 "optimized" } } */ -/* { dg-final { scan-tree-dump-times "\\* 10" 1 "optimized" } } */ +/* { dg-final { scan-tree-dump-times "\\* 40" 1 "optimized" } } */ /* { dg-final { scan-tree-dump-times "\\+ 200" 1 "optimized" } } */ /* { dg-final { scan-tree-dump-times "\\+ 40" 1 "optimized" } } */ -- 1.8.3.1