On 06/23/14 08:32, Richard Biener wrote:
On Mon, Jun 23, 2014 at 4:13 PM, Richard Henderson <r...@redhat.com> wrote:
On 06/20/2014 02:59 PM, Kai Tietz wrote:
So I suggest following change of passes.def:
Index: passes.def
===================================================================
--- passes.def (Revision 211850)
+++ passes.def (Arbeitskopie)
@@ -384,7 +384,6 @@ along with GCC; see the file COPYING3. If not see
NEXT_PASS (pass_rtl_dse2);
NEXT_PASS (pass_stack_adjustments);
NEXT_PASS (pass_jump2);
- NEXT_PASS (pass_peephole2);
NEXT_PASS (pass_if_after_reload);
NEXT_PASS (pass_regrename);
NEXT_PASS (pass_cprop_hardreg);
@@ -391,6 +390,7 @@ along with GCC; see the file COPYING3. If not see
NEXT_PASS (pass_fast_rtl_dce);
NEXT_PASS (pass_duplicate_computed_gotos);
NEXT_PASS (pass_reorder_blocks);
+ NEXT_PASS (pass_peephole2);
NEXT_PASS (pass_branch_target_load_optimize2);
NEXT_PASS (pass_leaf_regs);
NEXT_PASS (pass_split_before_sched2);
Looks good to me. I guess just keep an eye out for bug reports for other ports.
Maybe put a comment here because it looks like a random placement to me
which would be obvious to revert. peepholing before if-after-reload sounds
good anyway.
Definitely need a comment on the pass placement.
Btw, there is now no DCE after peephole2? Is peephole2 expected to
cleanup after itself?
There were cases where we wanted to change the insns we would output to
fit into the 4:1:1 issue model of the PPro, but to do so we needed to
know what registers were live/dead so that we could rewrite the insns
appropriately. It didn't fit well into what we could do in the
splitters and the old peephole ran too late. Dead code wasn't ever
really considered. At least that's my recollection. RTH might recall more.
I think it'd be worth an experiment here, but I think that can/should
happen independently of Kai's patch. Arguably the scheduler should have
all the necessary dataflow information to quickly identify any dead code.
Jeff
