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| author | Martin Jambor <mjambor@suse.cz> | 2020-10-02 18:41:35 +0200 |
|---|---|---|
| committer | Martin Jambor <mjambor@suse.cz> | 2020-10-02 18:41:35 +0200 |
| commit | 315848246657607d5acd9bca29d64d98a4c5f042 (patch) | |
| tree | e07cdcae1759f6aac27f5d6e3dd65f5544c1973b /gcc | |
| parent | 91153e0af9a457a0085bb796613a81404480d5af (diff) | |
| download | gcc-315848246657607d5acd9bca29d64d98a4c5f042.zip gcc-315848246657607d5acd9bca29d64d98a4c5f042.tar.gz gcc-315848246657607d5acd9bca29d64d98a4c5f042.tar.bz2 | |
ipa-cp: Separate and increase the large-unit parameter
A previous patch in the series has taught IPA-CP to identify the
important cloning opportunities in 548.exchange2_r as worthwhile on
their own, but the optimization is still prevented from taking place
because of the overall unit-growh limit. This patches raises that
limit so that it takes place and the benchmark runs 30% faster (on AMD
Zen2 CPU at least).
Before this patch, IPA-CP uses the following formulae to arrive at the
overall_size limit:
base = MAX(orig_size, param_large_unit_insns)
unit_growth_limit = base + base * param_ipa_cp_unit_growth / 100
since param_ipa_cp_unit_growth has default 10, param_large_unit_insns
has default value 10000.
The problem with exchange2 (at least on zen2 but I have had a quick
look on aarch64 too) is that the original estimated unit size is 10513
and so param_large_unit_insns does not apply and the default limit is
therefore 11564 which is good enough only for one of the ideal 8
clonings, we need the limit to be at least 16291.
I would like to raise param_ipa_cp_unit_growth a little bit more soon
too, but most certainly not to 55. Therefore, the large_unit must be
increased. In this patch, I decided to decouple the inlining and
ipa-cp large-unit parameters. It also makes sense because IPA-CP uses
it only at -O3 while inlining also at -O2 (IIUC). But if we agree we
can try raising param_large_unit_insns to 13-14 thousand
"instructions," perhaps it is not necessary. But then again, it may
make sense to actually increase the IPA-CP limit further.
I plan to experiment with IPA-CP tuning on a larger set of programs.
Meanwhile, mainly to address the 548.exchange2_r regression, I'm
suggesting this simple change.
gcc/ChangeLog:
2020-09-07 Martin Jambor <mjambor@suse.cz>
* params.opt (ipa-cp-large-unit-insns): New parameter.
* ipa-cp.c (get_max_overall_size): Use the new parameter.
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ipa-cp.c | 2 | ||||
| -rw-r--r-- | gcc/params.opt | 4 |
2 files changed, 5 insertions, 1 deletions
diff --git a/gcc/ipa-cp.c b/gcc/ipa-cp.c index 12acf24..2152f9e 100644 --- a/gcc/ipa-cp.c +++ b/gcc/ipa-cp.c @@ -3448,7 +3448,7 @@ static long get_max_overall_size (cgraph_node *node) { long max_new_size = orig_overall_size; - long large_unit = opt_for_fn (node->decl, param_large_unit_insns); + long large_unit = opt_for_fn (node->decl, param_ipa_cp_large_unit_insns); if (max_new_size < large_unit) max_new_size = large_unit; int unit_growth = opt_for_fn (node->decl, param_ipa_cp_unit_growth); diff --git a/gcc/params.opt b/gcc/params.opt index c0b94bb..6f308a1 100644 --- a/gcc/params.opt +++ b/gcc/params.opt @@ -214,6 +214,10 @@ Percentage penalty functions containing a single call to another function will r Common Joined UInteger Var(param_ipa_cp_unit_growth) Init(10) Param Optimization How much can given compilation unit grow because of the interprocedural constant propagation (in percent). +-param=ipa-cp-large-unit-insns= +Common Joined UInteger Var(param_ipa_cp_large_unit_insns) Optimization Init(16000) Param +The size of translation unit that IPA-CP pass considers large. + -param=ipa-cp-value-list-size= Common Joined UInteger Var(param_ipa_cp_value_list_size) Init(8) Param Optimization Maximum size of a list of values associated with each parameter for interprocedural constant propagation. |