From 4c342eacab7c0f3b27e9f070bec6c6138f9f6a00 Mon Sep 17 00:00:00 2001 From: jakub Date: Thu, 18 Apr 2002 10:39:41 +0000 Subject: * fold-const.c (fold) [NOP_EXPR]: Convert (T)(x&c) into ((T)x&(T)c) for integer constant c (if x has unsigned type or sign bit is not set in c). This folds the zero/sign extension into the bit-wise and operation. * gcc.c-torture/compile/20020415-1.c: New. git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@52465 138bc75d-0d04-0410-961f-82ee72b054a4 --- gcc/fold-const.c | 43 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) (limited to 'gcc/fold-const.c') diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 10a92fe412b..25214139252 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -4695,6 +4695,49 @@ fold (expr) TREE_USED (t) = 1; return t; } + + /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer + constants (if x has signed type, the sign bit cannot be set + in c). This folds extension into the BIT_AND_EXPR. */ + if (INTEGRAL_TYPE_P (TREE_TYPE (t)) + && TREE_CODE (TREE_OPERAND (t, 0)) == BIT_AND_EXPR + && TREE_CODE (TREE_OPERAND (TREE_OPERAND (t, 0), 1)) == INTEGER_CST) + { + tree and = TREE_OPERAND (t, 0); + tree and0 = TREE_OPERAND (and, 0), and1 = TREE_OPERAND (and, 1); + int change = 0; + + if (TREE_UNSIGNED (TREE_TYPE (and)) + || (TYPE_PRECISION (TREE_TYPE (t)) + <= TYPE_PRECISION (TREE_TYPE (and)))) + change = 1; + else if (TYPE_PRECISION (TREE_TYPE (and1)) + <= HOST_BITS_PER_WIDE_INT + && host_integerp (and1, 1)) + { + unsigned HOST_WIDE_INT cst; + + cst = tree_low_cst (and1, 1); + cst &= (HOST_WIDE_INT) -1 + << (TYPE_PRECISION (TREE_TYPE (and1)) - 1); + change = (cst == 0); +#ifdef LOAD_EXTEND_OP + if (change + && (LOAD_EXTEND_OP (TYPE_MODE (TREE_TYPE (and0))) + == ZERO_EXTEND)) + { + tree uns = unsigned_type (TREE_TYPE (and0)); + and0 = convert (uns, and0); + and1 = convert (uns, and1); + } +#endif + } + if (change) + return fold (build (BIT_AND_EXPR, TREE_TYPE (t), + convert (TREE_TYPE (t), and0), + convert (TREE_TYPE (t), and1))); + } + if (!wins) { TREE_CONSTANT (t) = TREE_CONSTANT (arg0); -- cgit v1.2.1