diff options
| author | Richard Kenner <kenner@gcc.gnu.org> | 1992-04-17 15:32:22 -0400 |
|---|---|---|
| committer | Richard Kenner <kenner@gcc.gnu.org> | 1992-04-17 15:32:22 -0400 |
| commit | a4bde0b117fa3575f34d259e5b62e577fe64ce83 (patch) | |
| tree | 5ca8bfff5defa9e837ebc9cbf7a1973392fdab0d /gcc | |
| parent | d0b97e0a2dc85fc16f79358c248720029f0526bc (diff) | |
| download | gcc-a4bde0b117fa3575f34d259e5b62e577fe64ce83.zip gcc-a4bde0b117fa3575f34d259e5b62e577fe64ce83.tar.gz gcc-a4bde0b117fa3575f34d259e5b62e577fe64ce83.tar.bz2 | |
*** empty log message ***
From-SVN: r764
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/combine.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/gcc/combine.c b/gcc/combine.c index bee3287..247f66a 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -2583,10 +2583,13 @@ subst (x, from, to, in_dest, unique_copy) } /* For a constant, try to pick up the part we want. Handle a full - word and low-order part. */ + word and low-order part. Only do this if we are narrowing + the constant; if it is being widened, we have no idea what + the extra bits will have been set to. */ if (CONSTANT_P (SUBREG_REG (x)) && op0_mode != VOIDmode && GET_MODE_SIZE (mode) == UNITS_PER_WORD + && GET_MODE_SIZE (op0_mode) < UNITS_PER_WORD && GET_MODE_CLASS (mode) == MODE_INT) { temp = operand_subword (SUBREG_REG (x), SUBREG_WORD (x), @@ -2595,7 +2598,8 @@ subst (x, from, to, in_dest, unique_copy) return temp; } - if (CONSTANT_P (SUBREG_REG (x)) && subreg_lowpart_p (x)) + if (CONSTANT_P (SUBREG_REG (x)) && subreg_lowpart_p (x) + && GET_MODE_SIZE (mode) < GET_MODE_SIZE (op0_mode)) return gen_lowpart_for_combine (mode, SUBREG_REG (x)); /* If we are narrowing the object, we need to see if we can simplify |