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| author | Jakub Jelinek <jakub@redhat.com> | 2016-03-29 20:49:00 +0200 |
|---|---|---|
| committer | Jakub Jelinek <jakub@gcc.gnu.org> | 2016-03-29 20:49:00 +0200 |
| commit | a362f023e538bc30dd9f2107f71c2435f62b9289 (patch) | |
| tree | 403c3e385daa0141fced2cc170fd23bc95606ee5 /gcc/combine.c | |
| parent | e0bffbbb5936be8b6a35d868db4226ca1b2365fa (diff) | |
| download | gcc-a362f023e538bc30dd9f2107f71c2435f62b9289.zip gcc-a362f023e538bc30dd9f2107f71c2435f62b9289.tar.gz gcc-a362f023e538bc30dd9f2107f71c2435f62b9289.tar.bz2 | |
re PR rtl-optimization/70429 (Wrong code with -O1.)
PR rtl-optimization/70429
* combine.c (simplify_shift_const_1): For ASHIFTRT don't optimize
(cst1 >> count) >> cst2 into (cst1 >> cst2) >> count if
mode != result_mode.
* gcc.c-torture/execute/pr70429.c: New test.
From-SVN: r234531
Diffstat (limited to 'gcc/combine.c')
| -rw-r--r-- | gcc/combine.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/gcc/combine.c b/gcc/combine.c index f701f28..1d0e8be 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -10533,6 +10533,11 @@ simplify_shift_const_1 (enum rtx_code code, machine_mode result_mode, >> orig_count, result_mode, &complement_p)) break; + /* For ((int) (cstLL >> count)) >> cst2 just give up. Queuing + up outer sign extension (often left and right shift) is + hardly more efficient than the original. See PR70429. */ + if (code == ASHIFTRT && mode != result_mode) + break; rtx new_rtx = simplify_const_binary_operation (code, mode, XEXP (varop, 0), |