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RA: Use simple LRA for huge functions

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The PR108500 test contains a huge function and RA spends a lot of time
to compile the test with -O0.  The patch decreases compilation time
considerably for huge functions.  Compilation time for the PR test
decreases from 1235s to 709s on Intel i7-13600K.

        PR tree-optimization/108500

gcc/ChangeLog:

	* params.opt (ira-simple-lra-insn-threshold): Add new param.
	* ira.cc (ira): Use the param to switch on simple LRA.
This commit is contained in:
Vladimir N. Makarov 2023-02-10 11:12:37 -05:00
parent 6493b7af37
commit 3c5154d0f0
2 changed files with 13 additions and 5 deletions
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14
gcc/ira.cc
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@ -5624,12 +5624,16 @@ ira (FILE *f)
if (DF_REG_DEF_COUNT (i) || DF_REG_USE_COUNT (i))
num_used_regs++;
/* 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. */
/* If there are too many pseudos and/or basic blocks (e.g. 10K pseudos and
10K blocks or 100K pseudos and 1K blocks) or we have too many function
insns, we will use simplified and faster algorithms in LRA. */
lra_simple_p
= ira_use_lra_p
&& num_used_regs >= (1U << 26) / last_basic_block_for_fn (cfun);
= (ira_use_lra_p
&& (num_used_regs >= (1U << 26) / last_basic_block_for_fn (cfun)
/* max uid is a good evaluation of the number of insns as most
optimizations are done on tree-SSA level. */
|| ((uint64_t) get_max_uid ()
> (uint64_t) param_ira_simple_lra_insn_threshold * 1000)));
if (lra_simple_p)
{

4
gcc/params.opt
View file

@ -302,6 +302,10 @@ The number of registers in each class kept unused by loop invariant motion.
Common Joined UInteger Var(param_ira_max_conflict_table_size) Init(1000) Param Optimization
Max size of conflict table in MB.
-param=ira-simple-lra-insn-threshold=
Common Joined UInteger Var(param_ira_simple_lra_insn_threshold) Init(1000) Param Optimization
Approximate function insn number in 1K units triggering simple local RA.
-param=ira-max-loops-num=
Common Joined UInteger Var(param_ira_max_loops_num) Init(100) Param Optimization
Max loops number for regional RA.