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| author | Richard Kenner <kenner@gcc.gnu.org> | 1994-08-25 17:43:46 -0400 |
|---|---|---|
| committer | Richard Kenner <kenner@gcc.gnu.org> | 1994-08-25 17:43:46 -0400 |
| commit | 5af6001b5e2e82b47fd38552d62e3b643adcff0a (patch) | |
| tree | 410c07bafde7ee82f7f27923c712276019b270da | |
| parent | 96a31ab889aca2a00133a92a5692e748fc7b6f0e (diff) | |
| download | gcc-5af6001b5e2e82b47fd38552d62e3b643adcff0a.zip gcc-5af6001b5e2e82b47fd38552d62e3b643adcff0a.tar.gz gcc-5af6001b5e2e82b47fd38552d62e3b643adcff0a.tar.bz2 | |
(shorten_compare): Don't issue warning if both operands constants and the...
(shorten_compare): Don't issue warning if both operands constants and
the signedness doesn't affect the comparison results.
From-SVN: r7981
| -rw-r--r-- | gcc/c-common.c | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/gcc/c-common.c b/gcc/c-common.c index 8109fc0..0d9184f 100644 --- a/gcc/c-common.c +++ b/gcc/c-common.c @@ -1457,9 +1457,11 @@ shorten_compare (op0_ptr, op1_ptr, restype_ptr, rescode_ptr) real2 = TREE_CODE (TREE_TYPE (primop1)) == REAL_TYPE; /* If first arg is constant, swap the args (changing operation - so value is preserved), for canonicalization. */ + so value is preserved), for canonicalization. Don't do this if + the second arg is 0. */ - if (TREE_CONSTANT (primop0)) + if (TREE_CONSTANT (primop0) + && ! integer_zerop (primop1) && ! real_zerop (primop1)) { register tree tem = primop0; register int temi = unsignedp0; @@ -1698,13 +1700,23 @@ shorten_compare (op0_ptr, op1_ptr, restype_ptr, rescode_ptr) switch (code) { case GE_EXPR: - if (extra_warnings) + /* All unsigned values are >= 0, so we warn if extra warnings + are requested. However, if OP0 is a constant that is + >= 0, the signedness of the comparison isn't an issue, + so suppress the warning. */ + if (extra_warnings + && ! (TREE_CODE (primop0) == INTEGER_CST + && ! TREE_OVERFLOW (convert (signed_type (type), + primop0)))) warning ("unsigned value >= 0 is always 1"); value = integer_one_node; break; case LT_EXPR: - if (extra_warnings) + if (extra_warnings + && ! (TREE_CODE (primop0) == INTEGER_CST + && ! TREE_OVERFLOW (convert (signed_type (type), + primop0)))) warning ("unsigned value < 0 is always 0"); value = integer_zero_node; } |