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| author | Eric Botcazou <ebotcazou@adacore.com> | 2015-05-28 15:45:08 +0000 |
|---|---|---|
| committer | Eric Botcazou <ebotcazou@gcc.gnu.org> | 2015-05-28 15:45:08 +0000 |
| commit | 396e67d21a3194da9d036bdb67e74edfd1030d3f (patch) | |
| tree | e352ee1b9a722c241fbc82e1122572bc6e8956cd /gcc/ada/gcc-interface/utils.c | |
| parent | afd6f7023570710172c76f5afc870d7ebd32678e (diff) | |
| download | gcc-396e67d21a3194da9d036bdb67e74edfd1030d3f.zip gcc-396e67d21a3194da9d036bdb67e74edfd1030d3f.tar.gz gcc-396e67d21a3194da9d036bdb67e74edfd1030d3f.tar.bz2 | |
utils.c (max_size): Add special code to deal with the subtraction of a "negative" value in an...
* gcc-interface/utils.c (max_size) <tcc_binary>: Add special code to
deal with the subtraction of a "negative" value in an unsigned type.
From-SVN: r223837
Diffstat (limited to 'gcc/ada/gcc-interface/utils.c')
| -rw-r--r-- | gcc/ada/gcc-interface/utils.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/gcc/ada/gcc-interface/utils.c b/gcc/ada/gcc-interface/utils.c index 7615d2d..0871c3c 100644 --- a/gcc/ada/gcc-interface/utils.c +++ b/gcc/ada/gcc-interface/utils.c @@ -3443,9 +3443,23 @@ max_size (tree exp, bool max_p) if ((code == MINUS_EXPR || code == PLUS_EXPR) && TREE_CODE (lhs) == INTEGER_CST && TREE_OVERFLOW (lhs) - && !TREE_CONSTANT (rhs)) + && TREE_CODE (rhs) != INTEGER_CST) return lhs; + /* If we are going to subtract a "negative" value in an unsigned type, + do the operation as an addition of the negated value, in order to + avoid creating a spurious overflow below. */ + if (code == MINUS_EXPR + && TYPE_UNSIGNED (type) + && TREE_CODE (rhs) == INTEGER_CST + && !TREE_OVERFLOW (rhs) + && tree_int_cst_sign_bit (rhs) != 0) + { + rhs = fold_build1 (NEGATE_EXPR, type, rhs); + code = PLUS_EXPR; + } + + /* We need to detect overflows so we call size_binop here. */ return size_binop (code, lhs, rhs); } |