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Re: [PATCH][IRA] Analysis of register usage of functions for usage by IRA.
- From: Tom de Vries <Tom_deVries at mentor dot com>
- To: Vladimir Makarov <vmakarov at redhat dot com>
- Cc: <gcc-patches at gcc dot gnu dot org>
- Date: Fri, 30 May 2014 11:20:33 +0200
- Subject: Re: [PATCH][IRA] Analysis of register usage of functions for usage by IRA.
- Authentication-results: sourceware.org; auth=none
- References: <510282FE dot 1060809 at mentor dot com> <5102A694 dot 5010000 at redhat dot com> <5113FC6B dot 7090702 at mentor dot com> <511C1538 dot 308 at redhat dot com> <514199BC dot 9070608 at mentor dot com> <52A11E8E dot 8090103 at mentor dot com> <52D591AA dot 4060103 at redhat dot com>
On 14-01-14 20:36, Vladimir Makarov wrote:
Unfortunately I haven't been able to find time to work further on the
>>LRA part.
>>So if you're still willing to pick up that part, that would be great.
>
>Vladimir,
>
>I gave this a try. The attached patch works for the included test-case
>for x86_64.
>
>I've bootstrapped and reg-tested the patch (in combination with the
>other patches from the series) on x86_64.
>
>OK for stage1?
>
Yes, it is ok for stage1. Thanks for not forgetting LRA and sorry for
the delay with the answer (it is not a high priority patch for me right
now).
I believe, this patch helps to improve code also because of better
spilling into SSE regs. Spilling into SSE regs instead of memory has a
rare probability right now as all SSE regs are call clobbered.
Vladimir,
After committing the original patch, Martin Liška told me on IRC that the patch
broke the build with --enable-checking=release.
The bit in lra_assign used the call_p field unconditionally, while the
definition of the call_p field is guarded with #ifdef ENABLE_CHECKING.
I've reverted the original patch, and bootstrapped and reg-tested this version
of the patch, which has a simplified bit for lra_assign.
The only functional difference between the patches is that we no longer add
printing a debug message in lra_assign. Committed (since the difference between
the approved and new patch is trivial).
Thanks,
- Tom
2014-05-30 Tom de Vries <tom@codesourcery.com>
* lra-int.h (struct lra_reg): Add field actual_call_used_reg_set.
* lra.c (initialize_lra_reg_info_element): Add init of
actual_call_used_reg_set field.
(lra): Call lra_create_live_ranges before lra_inheritance for
-fuse-caller-save.
* lra-assigns.c (lra_assign): Allow call_used_regs to cross calls for
-fuse-caller-save.
* lra-constraints.c (need_for_call_save_p): Use actual_call_used_reg_set
instead of call_used_reg_set for -fuse-caller-save.
* lra-lives.c (process_bb_lives): Calculate actual_call_used_reg_set.
diff --git a/gcc/lra-assigns.c b/gcc/lra-assigns.c
index f7bb86b..03c2506 100644
--- a/gcc/lra-assigns.c
+++ b/gcc/lra-assigns.c
@@ -1460,12 +1460,13 @@ lra_assign (void)
create_live_range_start_chains ();
setup_live_pseudos_and_spill_after_risky_transforms (&all_spilled_pseudos);
#ifdef ENABLE_CHECKING
- for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
- if (lra_reg_info[i].nrefs != 0 && reg_renumber[i] >= 0
- && lra_reg_info[i].call_p
- && overlaps_hard_reg_set_p (call_used_reg_set,
- PSEUDO_REGNO_MODE (i), reg_renumber[i]))
- gcc_unreachable ();
+ if (!flag_use_caller_save)
+ for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
+ if (lra_reg_info[i].nrefs != 0 && reg_renumber[i] >= 0
+ && lra_reg_info[i].call_p
+ && overlaps_hard_reg_set_p (call_used_reg_set,
+ PSEUDO_REGNO_MODE (i), reg_renumber[i]))
+ gcc_unreachable ();
#endif
/* Setup insns to process on the next constraint pass. */
bitmap_initialize (&changed_pseudo_bitmap, ®_obstack);
diff --git a/gcc/lra-constraints.c b/gcc/lra-constraints.c
index 2df841a..7eb9dbc 100644
--- a/gcc/lra-constraints.c
+++ b/gcc/lra-constraints.c
@@ -4605,7 +4605,10 @@ need_for_call_save_p (int regno)
lra_assert (regno >= FIRST_PSEUDO_REGISTER && reg_renumber[regno] >= 0);
return (usage_insns[regno].calls_num < calls_num
&& (overlaps_hard_reg_set_p
- (call_used_reg_set,
+ ((flag_use_caller_save &&
+ ! hard_reg_set_empty_p (lra_reg_info[regno].actual_call_used_reg_set))
+ ? lra_reg_info[regno].actual_call_used_reg_set
+ : call_used_reg_set,
PSEUDO_REGNO_MODE (regno), reg_renumber[regno])
|| HARD_REGNO_CALL_PART_CLOBBERED (reg_renumber[regno],
PSEUDO_REGNO_MODE (regno))));
diff --git a/gcc/lra-int.h b/gcc/lra-int.h
index 41c9849..3c89734 100644
--- a/gcc/lra-int.h
+++ b/gcc/lra-int.h
@@ -77,6 +77,10 @@ struct lra_reg
/* The following fields are defined only for pseudos. */
/* Hard registers with which the pseudo conflicts. */
HARD_REG_SET conflict_hard_regs;
+ /* Call used registers with which the pseudo conflicts, taking into account
+ the registers used by functions called from calls which cross the
+ pseudo. */
+ HARD_REG_SET actual_call_used_reg_set;
/* We assign hard registers to reload pseudos which can occur in few
places. So two hard register preferences are enough for them.
The following fields define the preferred hard registers. If
diff --git a/gcc/lra-lives.c b/gcc/lra-lives.c
index 8444ade..26ba0d2 100644
--- a/gcc/lra-lives.c
+++ b/gcc/lra-lives.c
@@ -624,6 +624,17 @@ process_bb_lives (basic_block bb, int &curr_point)
if (call_p)
{
+ if (flag_use_caller_save)
+ {
+ HARD_REG_SET this_call_used_reg_set;
+ get_call_reg_set_usage (curr_insn, &this_call_used_reg_set,
+ call_used_reg_set);
+
+ EXECUTE_IF_SET_IN_SPARSESET (pseudos_live, j)
+ IOR_HARD_REG_SET (lra_reg_info[j].actual_call_used_reg_set,
+ this_call_used_reg_set);
+ }
+
sparseset_ior (pseudos_live_through_calls,
pseudos_live_through_calls, pseudos_live);
if (cfun->has_nonlocal_label
diff --git a/gcc/lra.c b/gcc/lra.c
index ecec890..d199a81 100644
--- a/gcc/lra.c
+++ b/gcc/lra.c
@@ -1427,6 +1427,7 @@ initialize_lra_reg_info_element (int i)
lra_reg_info[i].no_stack_p = false;
#endif
CLEAR_HARD_REG_SET (lra_reg_info[i].conflict_hard_regs);
+ CLEAR_HARD_REG_SET (lra_reg_info[i].actual_call_used_reg_set);
lra_reg_info[i].preferred_hard_regno1 = -1;
lra_reg_info[i].preferred_hard_regno2 = -1;
lra_reg_info[i].preferred_hard_regno_profit1 = 0;
@@ -2344,7 +2345,18 @@ lra (FILE *f)
lra_eliminate (false, false);
/* Do inheritance only for regular algorithms. */
if (! lra_simple_p)
- lra_inheritance ();
+ {
+ if (flag_use_caller_save)
+ {
+ if (live_p)
+ lra_clear_live_ranges ();
+ /* As a side-effect of lra_create_live_ranges, we calculate
+ actual_call_used_reg_set, which is needed during
+ lra_inheritance. */
+ lra_create_live_ranges (true);
+ }
+ lra_inheritance ();
+ }
if (live_p)
lra_clear_live_ranges ();
/* We need live ranges for lra_assign -- so build them. */
--
1.9.1