diff options
Diffstat (limited to 'gcc/fold-const.c')
| -rw-r--r-- | gcc/fold-const.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 66e72a7..ce5673e 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -8568,7 +8568,9 @@ fold_comparison (enum tree_code code, tree type, tree op0, tree op1) because pointer arithmetic is restricted to retain within an object and overflow on pointer differences is undefined as of 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */ - else if (bitpos0 == bitpos1) + else if (bitpos0 == bitpos1 + && ((code == EQ_EXPR || code == NE_EXPR) + || POINTER_TYPE_OVERFLOW_UNDEFINED)) { tree signed_size_type_node; signed_size_type_node = signed_type_for (size_type_node); @@ -8587,6 +8589,12 @@ fold_comparison (enum tree_code code, tree type, tree op0, tree op1) else offset1 = fold_convert (signed_size_type_node, offset1); + if (code != EQ_EXPR && code != NE_EXPR) + fold_overflow_warning (("assuming pointer wraparound does not " + "occur when comparing P +- C1 with " + "P +- C2"), + WARN_STRICT_OVERFLOW_COMPARISON); + return fold_build2 (code, type, offset0, offset1); } } @@ -9711,7 +9719,7 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1) /* With undefined overflow we can only associate constants with one variable. */ - if ((POINTER_TYPE_P (type) + if (((POINTER_TYPE_P (type) && POINTER_TYPE_OVERFLOW_UNDEFINED) || (INTEGRAL_TYPE_P (type) && !TYPE_OVERFLOW_WRAPS (type))) && var0 && var1) { |