diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 1995605a6803771ef1f3f5d634fa6af2f3165227..b18b1e4ec0f093a3d1b753658caa7e723057a2e0 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2005-06-12 James A. Morrison <phython@gcc.gnu.org> + + PR tree-optimization/14796 + * fold-const (fold_binary): Transform (X << C) >> C into X & (-1>>C) + for unsigned types. + 2005-06-12 Kazu Hirata <kazu@codesourcery.com> * cgraphunit.c, tree-ssa-loop-ivopts.c, diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 1994410d4be8b7d3338d194f0ce94bda60c4e12e..af3f01c38df23b5a2b93a5dbd711cf43384d2ad2 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -8768,8 +8768,11 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1) build_int_cst (type, low)); } - /* Transform (x >> c) << c into x & (-1<<c) */ - if (code == LSHIFT_EXPR && TREE_CODE (arg0) == RSHIFT_EXPR + /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c + into x & ((unsigned)-1 >> c) for unsigned types. */ + if (((code == LSHIFT_EXPR && TREE_CODE (arg0) == RSHIFT_EXPR) + || (TYPE_UNSIGNED (type) + && code == RSHIFT_EXPR && TREE_CODE (arg0) == LSHIFT_EXPR)) && host_integerp (arg1, false) && TREE_INT_CST_LOW (arg1) < TYPE_PRECISION (type) && host_integerp (TREE_OPERAND (arg0, 1), false) @@ -8777,8 +8780,6 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1) { HOST_WIDE_INT low0 = TREE_INT_CST_LOW (TREE_OPERAND (arg0, 1)); HOST_WIDE_INT low1 = TREE_INT_CST_LOW (arg1); - unsigned HOST_WIDE_INT low; - HOST_WIDE_INT high; tree lshift; tree arg00; @@ -8786,15 +8787,13 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1) { arg00 = fold_convert (type, TREE_OPERAND (arg0, 0)); - lshift_double (-1, -1, low0 < low1 ? low0 : low1, - TYPE_PRECISION (type), &low, &high, 1); - lshift = build_int_cst_wide (type, low, high); + lshift = build_int_cst (type, -1); + lshift = int_const_binop (code, lshift, arg1, 0); return fold_build2 (BIT_AND_EXPR, type, arg00, lshift); } } - /* Rewrite an LROTATE_EXPR by a constant into an RROTATE_EXPR by a new constant. */ if (code == LROTATE_EXPR && TREE_CODE (arg1) == INTEGER_CST) diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 9ae809b5d0ee8f48d5e8df09c50bce48abbe833a..0baaf8a6e86688ffe649e437012165d9ede8bb6f 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,7 @@ +2005-06-12 James A. Morrison <phython@gcc.gnu.org> + + * ggcc.dg/pr14796-1.c: Add tests for (X << C) >> C. + 2005-06-12 Roger Sayle <roger@eyesopen.com> PR c++/21930 diff --git a/gcc/testsuite/gcc.dg/pr14796-1.c b/gcc/testsuite/gcc.dg/pr14796-1.c index c927e2b54036f18dafd5eacb1b08dfa779245237..7ddc4fe3467c07262d43225e9644d2978887038b 100644 --- a/gcc/testsuite/gcc.dg/pr14796-1.c +++ b/gcc/testsuite/gcc.dg/pr14796-1.c @@ -9,6 +9,16 @@ int g (int b) { return (b >> 5) << 5; } +unsigned long long h (unsigned long long c) { + return (c << 60) >> 60; +} + +int l (int d) { + return (d << 6) >> 6; +} + /* { dg-final { scan-tree-dump "a << 9" "gimple" } } */ /* { dg-final { scan-tree-dump "b & -32" "gimple" } } */ +/* { dg-final { scan-tree-dump "c & 15" "gimple" } } */ +/* { dg-final { scan-tree-dump "d << 6" "gimple" } } */ /* { dg-final { cleanup-tree-dump "gimple" } } */