diff options
| author | Jeff Law <law@redhat.com> | 2015-04-15 12:24:28 +0000 |
|---|---|---|
| committer | Jeff Law <law@redhat.com> | 2015-04-15 12:24:28 +0000 |
| commit | 789cbefcb43d009e91ae79bb9d613c8362a18ac9 (patch) | |
| tree | 1d0879dbbab7c2c5b15c92110904392c69270b07 | |
| parent | 24e81ca680297ffa6e5e8d86b222bd2e19c1f2ee (diff) | |
PR rtl-optimization/42522
* cse.c (fold_rtx): Try to simplify a ZERO_EXTRACT or
SIGN_EXTRACT as a whole object rather than simplifying
its operand.
git-svn-id: https://gcc.gnu.org/svn/gcc/trunk@222125 138bc75d-0d04-0410-961f-82ee72b054a4
| -rw-r--r-- | gcc/ChangeLog | 7 | ||||
| -rw-r--r-- | gcc/cse.c | 9 |
2 files changed, 16 insertions, 0 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index f1a96f270b5..a0f2fe7e2b9 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,10 @@ +2015-04-15 Jeff Law <law@redhat.com> + + PR rtl-optimization/42522 + * cse.c (fold_rtx): Try to simplify a ZERO_EXTRACT or + SIGN_EXTRACT as a whole object rather than simplifying + its operand. + 2015-04-15 Jakub Jelinek <jakub@redhat.com> PR ipa/65765 diff --git a/gcc/cse.c b/gcc/cse.c index 2a33827a61c..d7638f051f3 100644 --- a/gcc/cse.c +++ b/gcc/cse.c @@ -3150,6 +3150,15 @@ fold_rtx (rtx x, rtx_insn *insn) { case MEM: case SUBREG: + /* The first operand of a SIGN/ZERO_EXTRACT has a different meaning + than it would in other contexts. Basically its mode does not + signify the size of the object read. That information is carried + by size operand. If we happen to have a MEM of the appropriate + mode in our tables with a constant value we could simplify the + extraction incorrectly if we allowed substitution of that value + for the MEM. */ + case ZERO_EXTRACT: + case SIGN_EXTRACT: if ((new_rtx = equiv_constant (x)) != NULL_RTX) return new_rtx; return x; |