diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 9fc4c2a..efe77e7 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -11596,45 +11596,53 @@ fold_binary_loc (location_t loc, enum tree_code code, tree type, C1 is a valid shift constant, and C2 is a power of two, i.e. a single bit. */ if (TREE_CODE (arg0) == BIT_AND_EXPR - && TREE_CODE (TREE_OPERAND (arg0, 0)) == RSHIFT_EXPR - && TREE_CODE (TREE_OPERAND (TREE_OPERAND (arg0, 0), 1)) - == INTEGER_CST && integer_pow2p (TREE_OPERAND (arg0, 1)) && integer_zerop (arg1)) { - tree itype = TREE_TYPE (arg0); - tree arg001 = TREE_OPERAND (TREE_OPERAND (arg0, 0), 1); - prec = TYPE_PRECISION (itype); - - /* Check for a valid shift count. */ - if (wi::ltu_p (wi::to_wide (arg001), prec)) + tree arg00 = TREE_OPERAND (arg0, 0); + STRIP_NOPS (arg00); + if (TREE_CODE (arg00) == RSHIFT_EXPR + && TREE_CODE (TREE_OPERAND (arg00, 1)) == INTEGER_CST) { - tree arg01 = TREE_OPERAND (arg0, 1); - tree arg000 = TREE_OPERAND (TREE_OPERAND (arg0, 0), 0); - unsigned HOST_WIDE_INT log2 = tree_log2 (arg01); - /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0 - can be rewritten as (X & (C2 << C1)) != 0. */ - if ((log2 + TREE_INT_CST_LOW (arg001)) < prec) + tree itype = TREE_TYPE (arg00); + tree arg001 = TREE_OPERAND (arg00, 1); + prec = TYPE_PRECISION (itype); + + /* Check for a valid shift count. */ + if (wi::ltu_p (wi::to_wide (arg001), prec)) { - tem = fold_build2_loc (loc, LSHIFT_EXPR, itype, arg01, arg001); - tem = fold_build2_loc (loc, BIT_AND_EXPR, itype, arg000, tem); - return fold_build2_loc (loc, code, type, tem, - fold_convert_loc (loc, itype, arg1)); - } - /* Otherwise, for signed (arithmetic) shifts, - ((X >> C1) & C2) != 0 is rewritten as X < 0, and - ((X >> C1) & C2) == 0 is rewritten as X >= 0. */ - else if (!TYPE_UNSIGNED (itype)) - return fold_build2_loc (loc, code == EQ_EXPR ? GE_EXPR : LT_EXPR, type, - arg000, build_int_cst (itype, 0)); - /* Otherwise, of unsigned (logical) shifts, - ((X >> C1) & C2) != 0 is rewritten as (X,false), and - ((X >> C1) & C2) == 0 is rewritten as (X,true). */ - else - return omit_one_operand_loc (loc, type, + tree arg01 = TREE_OPERAND (arg0, 1); + tree arg000 = TREE_OPERAND (arg00, 0); + unsigned HOST_WIDE_INT log2 = tree_log2 (arg01); + /* If (C2 << C1) doesn't overflow, then + ((X >> C1) & C2) != 0 can be rewritten as + (X & (C2 << C1)) != 0. */ + if ((log2 + TREE_INT_CST_LOW (arg001)) < prec) + { + tem = fold_build2_loc (loc, LSHIFT_EXPR, itype, + arg01, arg001); + tem = fold_build2_loc (loc, BIT_AND_EXPR, itype, + arg000, tem); + return fold_build2_loc (loc, code, type, tem, + fold_convert_loc (loc, itype, arg1)); + } + /* Otherwise, for signed (arithmetic) shifts, + ((X >> C1) & C2) != 0 is rewritten as X < 0, and + ((X >> C1) & C2) == 0 is rewritten as X >= 0. */ + else if (!TYPE_UNSIGNED (itype)) + return fold_build2_loc (loc, code == EQ_EXPR ? GE_EXPR + : LT_EXPR, + type, arg000, + build_int_cst (itype, 0)); + /* Otherwise, of unsigned (logical) shifts, + ((X >> C1) & C2) != 0 is rewritten as (X,false), and + ((X >> C1) & C2) == 0 is rewritten as (X,true). */ + else + return omit_one_operand_loc (loc, type, code == EQ_EXPR ? integer_one_node : integer_zero_node, arg000); + } } }