diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 9956b2c..7ff66cd 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -9942,6 +9942,22 @@ exact_inverse (tree type, tree cst) } } +/* Mask out the tz least significant bits of X of type TYPE where + tz is the number of trailing zeroes in Y. */ +static double_int +mask_with_tz (tree type, double_int x, double_int y) +{ + int tz = y.trailing_zeros (); + if (tz > 0) + { + double_int mask; + mask = ~double_int::mask (tz); + mask = mask.ext (TYPE_PRECISION (type), TYPE_UNSIGNED (type)); + return mask & x; + } + return x; +} + /* Fold a binary expression of code CODE and type TYPE with operands OP0 and OP1. LOC is the location of the resulting expression. Return the folded expression if folding is successful. Otherwise, @@ -11266,6 +11282,7 @@ fold_binary_loc (location_t loc, { double_int c1, c2, c3, msk; int width = TYPE_PRECISION (type), w; + bool valid = true; c1 = tree_to_double_int (TREE_OPERAND (arg0, 1)); c2 = tree_to_double_int (arg1); @@ -11300,7 +11317,19 @@ fold_binary_loc (location_t loc, break; } } - if (c3 != c1) + /* 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)); + valid = masked != c1; + } + + if (c3 != c1 && valid) return fold_build2_loc (loc, BIT_IOR_EXPR, type, fold_build2_loc (loc, BIT_AND_EXPR, type, TREE_OPERAND (arg0, 0), @@ -11690,22 +11719,16 @@ fold_binary_loc (location_t loc, && TREE_CODE (arg0) == MULT_EXPR && TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST) { - int arg1tz - = tree_to_double_int (TREE_OPERAND (arg0, 1)).trailing_zeros (); - if (arg1tz > 0) - { - double_int arg1mask, masked; - arg1mask = ~double_int::mask (arg1tz); - arg1mask = arg1mask.ext (TYPE_PRECISION (type), - TYPE_UNSIGNED (type)); - masked = arg1mask & tree_to_double_int (arg1); - 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)); - } + double_int masked + = mask_with_tz (type, tree_to_double_int (arg1), + 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)); } /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M, diff --git a/gcc/testsuite/gcc.c-torture/compile/pr58088.c b/gcc/testsuite/gcc.c-torture/compile/pr58088.c new file mode 100644 index 0000000..07a9c68 --- /dev/null +++ b/gcc/testsuite/gcc.c-torture/compile/pr58088.c @@ -0,0 +1,5 @@ +int +bar (int i) +{ + return 1 | ((i * 2) & 254); +}