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[lra] patch to improve live-range splitting
- From: Vladimir Makarov <vmakarov at redhat dot com>
- To: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Fri, 15 Jun 2012 19:22:40 -0400
- Subject: [lra] patch to improve live-range splitting
The following patch improves splitting heuristic (and overall SPEC2000
performance). The previous one was aggressive for local pseudos. We
don't need to split local pseudo ranges as inheritance works well for
them and achieves the same results.
The patch was successfully bootstrapped on x86/x86-64.
Committed as rev. 188685.
2012-06-15 Vladimir Makarov <vmakarov@redhat.com>
* lra-constraints.c (ebb_global_regs): New.
(need_for_split_p): Use it.
(lra_inheritance): Allocate/deallocate/set it.
Index: lra-constraints.c
===================================================================
--- lra-constraints.c (revision 188388)
+++ lra-constraints.c (working copy)
@@ -3877,6 +3877,9 @@ need_for_call_save_p (int regno)
call_used_reg_set)));
}
+/* Registers cannot be involved in splitting in the current EBB. */
+static bitmap_head ebb_global_regs;
+
/* Return true if we need a split for hard register REGNO or pseudo
REGNO which was assigned to a hard register.
POTENTIAL_RELOAD_HARD_REGS contains hard registers which might be
@@ -3898,7 +3901,11 @@ need_for_split_p (HARD_REG_SET potential
return ((TEST_HARD_REG_BIT (potential_reload_hard_regs, hard_regno)
&& ! TEST_HARD_REG_BIT (lra_no_alloc_regs, hard_regno)
&& (usage_insns[regno].reloads_num
- + (regno < FIRST_PSEUDO_REGISTER ? 0 : 2) < reloads_num))
+ + (regno < FIRST_PSEUDO_REGISTER ? 0 : 2) < reloads_num)
+ && ((regno < FIRST_PSEUDO_REGISTER
+ && ! bitmap_bit_p (&ebb_global_regs, regno))
+ || (regno >= FIRST_PSEUDO_REGISTER && lra_reg_info[regno].nrefs > 3
+ && bitmap_bit_p (&ebb_global_regs, regno))))
|| (regno >= FIRST_PSEUDO_REGISTER && need_for_call_save_p (regno)));
}
@@ -4683,12 +4690,15 @@ lra_inheritance (void)
bitmap_initialize (&check_only_regs, ®_obstack);
bitmap_initialize (&live_regs, ®_obstack);
bitmap_initialize (&temp_bitmap, ®_obstack);
+ bitmap_initialize (&ebb_global_regs, ®_obstack);
FOR_EACH_BB (bb)
{
start_bb = bb;
if (lra_dump_file != NULL)
fprintf (lra_dump_file, "EBB");
/* Form a EBB starting with BB. */
+ bitmap_clear (&ebb_global_regs);
+ bitmap_ior_into (&ebb_global_regs, DF_LR_IN (bb));
for (;;)
{
if (lra_dump_file != NULL)
@@ -4702,6 +4712,7 @@ lra_inheritance (void)
break;
bb = bb->next_bb;
}
+ bitmap_ior_into (&ebb_global_regs, DF_LR_OUT (bb));
if (lra_dump_file != NULL)
fprintf (lra_dump_file, "\n");
if (inherit_in_ebb (BB_HEAD (start_bb), BB_END (bb)))
@@ -4709,6 +4720,7 @@ lra_inheritance (void)
inherit_in_ebb. */
update_ebb_live_info (BB_HEAD (start_bb), BB_END (bb));
}
+ bitmap_clear (&ebb_global_regs);
bitmap_clear (&temp_bitmap);
bitmap_clear (&live_regs);
bitmap_clear (&check_only_regs);