From: Andrew Pinski <apin...@marvell.com> 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. --- gcc/match.pd | 10 ++++++++ gcc/testsuite/gcc.dg/tree-ssa/pr103218-1.c | 28 ++++++++++++++++++++++ 2 files changed, 38 insertions(+) create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr103218-1.c diff --git a/gcc/match.pd b/gcc/match.pd index a319aefa808..df31964e02f 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 00000000000..f086f073b38 --- /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"} } */ -- 2.17.1