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re PR rtl-optimization/88751 (Performance regression reload vs lra)

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Fix PR88751

This patch implements a small improvement for the heuristic in lra
which decides when it has to activate the simpler register allocation
algorithm.

gcc/ChangeLog:

2019-06-06  Andreas Krebbel  <krebbel@linux.ibm.com>

	PR rtl-optimization/88751
	* ira.c (ira): Use the number of the actually referenced registers
	when calculating the threshold.

From-SVN: r271996
This commit is contained in:
Andreas Krebbel 2019-06-06 11:35:04 +00:00 committed by Andreas Krebbel
parent a96ed9f7d9
commit 891f31f9a4
2 changed files with 14 additions and 1 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2019-06-06 Andreas Krebbel <krebbel@linux.ibm.com>
PR rtl-optimization/88751
* ira.c (ira): Use the number of the actually referenced registers
when calculating the threshold.
2019-06-06 Jakub Jelinek <jakub@redhat.com>
* configure: Regenerate.

9
gcc/ira.c
View File

@ -5198,6 +5198,8 @@ ira (FILE *f)
int ira_max_point_before_emit;
bool saved_flag_caller_saves = flag_caller_saves;
enum ira_region saved_flag_ira_region = flag_ira_region;
unsigned int i;
int num_used_regs = 0;
clear_bb_flags ();
@ -5213,12 +5215,17 @@ ira (FILE *f)
ira_conflicts_p = optimize > 0;
/* Determine the number of pseudos actually requiring coloring. */
for (i = FIRST_PSEUDO_REGISTER; i < DF_REG_SIZE (df); i++)
num_used_regs += !!(DF_REG_USE_COUNT (i) + DF_REG_DEF_COUNT (i));
/* If there are too many pseudos and/or basic blocks (e.g. 10K
pseudos and 10K blocks or 100K pseudos and 1K blocks), we will
use simplified and faster algorithms in LRA. */
lra_simple_p
= (ira_use_lra_p
&& max_reg_num () >= (1 << 26) / last_basic_block_for_fn (cfun));
&& num_used_regs >= (1 << 26) / last_basic_block_for_fn (cfun));
if (lra_simple_p)
{
/* It permits to skip live range splitting in LRA. */