From 7e2c9f14348d8ed9192a94b269138a5a5f57b92a Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Mon, 5 May 2014 09:23:31 +0000 Subject: re PR middle-end/61010 (Infinite recursion in fold) 2014-05-05 Richard Biener PR middle-end/61010 * fold-const.c (fold_binary_loc): Consistently avoid canonicalizing X & CST away from a CST that is the mask of a mode. * gcc.dg/torture/pr61010.c: New testcase. From-SVN: r210066 --- gcc/fold-const.c | 33 ++++++++++++++------------------- 1 file changed, 14 insertions(+), 19 deletions(-) (limited to 'gcc/fold-const.c') diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 5c2bf25..65051a1 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -11426,7 +11426,6 @@ fold_binary_loc (location_t loc, { double_int c1, c2, c3, msk; int width = TYPE_PRECISION (type), w; - bool try_simplify = true; c1 = tree_to_double_int (TREE_OPERAND (arg0, 1)); c2 = tree_to_double_int (arg1); @@ -11463,20 +11462,7 @@ fold_binary_loc (location_t loc, } } - /* If X is a tree of the form (Y * K1) & K2, this might conflict - with that optimization from the BIT_AND_EXPR optimizations. - This could end up in an infinite recursion. */ - if (TREE_CODE (TREE_OPERAND (arg0, 0)) == MULT_EXPR - && TREE_CODE (TREE_OPERAND (TREE_OPERAND (arg0, 0), 1)) - == INTEGER_CST) - { - tree t = TREE_OPERAND (TREE_OPERAND (arg0, 0), 1); - double_int masked = mask_with_tz (type, c3, tree_to_double_int (t)); - - try_simplify = (masked != c1); - } - - if (try_simplify && c3 != c1) + if (c3 != c1) return fold_build2_loc (loc, BIT_IOR_EXPR, type, fold_build2_loc (loc, BIT_AND_EXPR, type, TREE_OPERAND (arg0, 0), @@ -11866,16 +11852,25 @@ fold_binary_loc (location_t loc, && TREE_CODE (arg0) == MULT_EXPR && TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST) { + double_int darg1 = tree_to_double_int (arg1); double_int masked - = mask_with_tz (type, tree_to_double_int (arg1), + = mask_with_tz (type, darg1, tree_to_double_int (TREE_OPERAND (arg0, 1))); if (masked.is_zero ()) return omit_two_operands_loc (loc, type, build_zero_cst (type), arg0, arg1); - else if (masked != tree_to_double_int (arg1)) - return fold_build2_loc (loc, code, type, op0, - double_int_to_tree (type, masked)); + else if (masked != darg1) + { + /* Avoid the transform if arg1 is a mask of some + mode which allows further optimizations. */ + int pop = darg1.popcount (); + if (!(pop >= BITS_PER_UNIT + && exact_log2 (pop) != -1 + && double_int::mask (pop) == darg1)) + return fold_build2_loc (loc, code, type, op0, + double_int_to_tree (type, masked)); + } } /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M, -- cgit v1.1