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| author | Segher Boessenkool <segher@kernel.crashing.org> | 2017-12-08 12:26:35 +0100 |
|---|---|---|
| committer | Segher Boessenkool <segher@gcc.gnu.org> | 2017-12-08 12:26:35 +0100 |
| commit | b1cf82933e894cbdb21d63653c20258dc8c87997 (patch) | |
| tree | 2485c2d642b628103a2d85dd86d4c6aeb9dc1714 /gcc | |
| parent | da472c1b3bc8b2289f93cacaf75472556a3d85cd (diff) | |
| download | gcc-b1cf82933e894cbdb21d63653c20258dc8c87997.zip gcc-b1cf82933e894cbdb21d63653c20258dc8c87997.tar.gz gcc-b1cf82933e894cbdb21d63653c20258dc8c87997.tar.bz2 | |
combine: Fix PR83304
In PR83304 two insns are combined, where the I2 uses a register that
has a REG_DEAD note on an insn after I2 but before I3. In such a case
move_deaths should move that death note. But move_deaths only looks
at the reg_stat[regno].last_death insn, and that field can be zeroed
out (previously, use_crosses_set_p would prevent the combination in
this case).
If the last_death field is zero it means "unknown", not "no death", so
we have to find if there is a REG_DEAD note.
PR rtl-optimization/83304
* combine.c (move_deaths): If we do not know where a register died,
search for it.
From-SVN: r255506
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ChangeLog | 6 | ||||
| -rw-r--r-- | gcc/combine.c | 20 |
2 files changed, 26 insertions, 0 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index e8aa3a1..dcd1fb6 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2017-12-08 Segher Boessenkool <segher@kernel.crashing.org> + + PR rtl-optimization/83304 + * combine.c (move_deaths): If we do not know where a register died, + search for it. + 2017-12-08 Richard Biener <rguenther@suse.de> * gimple-loop-interchange.cc (tree_loop_interchange::interchange): diff --git a/gcc/combine.c b/gcc/combine.c index 34c89a1..786a840 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -13876,6 +13876,26 @@ move_deaths (rtx x, rtx maybe_kill_insn, int from_luid, rtx_insn *to_insn, unsigned int regno = REGNO (x); rtx_insn *where_dead = reg_stat[regno].last_death; + /* If we do not know where the register died, it may still die between + FROM_LUID and TO_INSN. If so, find it. This is PR83304. */ + if (!where_dead) + { + rtx_insn *insn = prev_real_insn (to_insn); + while (insn + && BLOCK_FOR_INSN (insn) == BLOCK_FOR_INSN (to_insn) + && DF_INSN_LUID (insn) >= from_luid) + { + if (dead_or_set_regno_p (insn, regno)) + { + if (find_regno_note (insn, REG_DEAD, regno)) + where_dead = insn; + break; + } + + insn = prev_real_insn (insn); + } + } + /* Don't move the register if it gets killed in between from and to. */ if (maybe_kill_insn && reg_set_p (x, maybe_kill_insn) && ! reg_referenced_p (x, maybe_kill_insn)) |