On Fri, Jan 15, 2021 at 09:21:07PM +0100, Richard Biener wrote: > >BTW, I've tried to also fix what the PR wanted primarily by adding > >/* Simplify (CST << x) & 1 to 0 if CST is even or to x == 0 if it is > >odd. / > >(simplify > > (bit_and (lshift INTEGER_CST@1 @0) integer_onep) > > (if ((wi::to_wide (@1) & 1) != 0) > > (eq @0 { build_zero_cst (TREE_TYPE (@0)); }) > > ({ build_zero_cst (type); }))) > >simplifier before this one, but genmatch.c doesn't seem to put it into > >the > >resulting files. Is there a way to figure out what is going on?
Actually, it was a PEBKAC, it helps when the comment termination is */ rather than just / alone. The following works fine, no need to stick it into an unrelated pattern. Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? 2021-01-15 Jakub Jelinek <ja...@redhat.com> PR tree-optimization/96669 * match.pd ((CST << x) & 1 -> x == 0): New simplification. * gcc.dg/tree-ssa/pr96669-1.c: Adjust regexp. * gcc.dg/tree-ssa/pr96669-2.c: New test. --- gcc/match.pd.jj 2021-01-15 21:12:07.656060308 +0100 +++ gcc/match.pd 2021-01-15 23:51:34.038119715 +0100 @@ -3117,6 +3117,13 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) (op @0 { build_int_cst (TREE_TYPE (@1), low); }))))))) +/* Simplify (CST << x) & 1 to 0 if CST is even or to x == 0 if it is odd. */ +(simplify + (bit_and (lshift INTEGER_CST@1 @0) integer_onep) + (if ((wi::to_wide (@1) & 1) != 0) + (convert (eq:boolean_type_node @0 { build_zero_cst (TREE_TYPE (@0)); })) + { build_zero_cst (type); })) + /* Simplify ((C << x) & D) != 0 where C and D are power of two constants, either to false if D is smaller (unsigned comparison) than C, or to x == log2 (D) - log2 (C). Similarly for right shifts. */ --- gcc/testsuite/gcc.dg/tree-ssa/pr96669-1.c.jj 2021-01-15 22:03:18.089279035 +0100 +++ gcc/testsuite/gcc.dg/tree-ssa/pr96669-1.c 2021-01-16 01:55:42.800379400 +0100 @@ -1,7 +1,7 @@ /* PR tree-optimization/96669 */ /* { dg-do compile } */ /* { dg-options "-O2 -fdump-tree-original" } */ -/* { dg-final { scan-tree-dump "return a == 0;" "original" } } */ +/* { dg-final { scan-tree-dump "a == 0" "original" } } */ /* { dg-final { scan-tree-dump "return 1;" "original" } } */ /* { dg-final { scan-tree-dump "return c == 3;" "original" } } */ /* { dg-final { scan-tree-dump "return d != 1;" "original" } } */ --- gcc/testsuite/gcc.dg/tree-ssa/pr96669-2.c.jj 2021-01-15 22:03:47.075951818 +0100 +++ gcc/testsuite/gcc.dg/tree-ssa/pr96669-2.c 2021-01-16 01:56:02.859156051 +0100 @@ -0,0 +1,30 @@ +/* PR tree-optimization/96669 */ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-original" } */ +/* { dg-final { scan-tree-dump "a == 0" "original" } } */ +/* { dg-final { scan-tree-dump-times "return 0;" 2 "original" } } */ +/* { dg-final { scan-tree-dump "c == 0" "original" } } */ + +int +f1 (int a) +{ + return ((1 << a) & 1); +} + +int +f2 (int b) +{ + return ((2 << b) & 1); +} + +int +f3 (int c) +{ + return ((35 << c) & 1); +} + +int +f4 (int d) +{ + return ((42 << d) & 1); +} Jakub