[PATCH x86] Increase PARAM_MAX_COMPLETELY_PEELED_INSNS when branch is costly
Evgeny Stupachenko
evstupac@gmail.com
Mon Oct 27 08:23:00 GMT 2014
The results are the same for Silvermont.
There are no significant changes on Haswell.
So I agree with Richard, let's enable this x86 wide.
Bootstrap/ passed.
Make check in progress.
Is it ok?
2014-10-25 Evgeny Stupachenko <evstupac@gmail.com>
* config/i386/i386.c (ix86_option_override_internal): Increase
PARAM_MAX_COMPLETELY_PEELED_INSNS.
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 6337aa5..5ac10eb 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -4081,6 +4081,12 @@ ix86_option_override_internal (bool main_args_p,
opts->x_param_values,
opts_set->x_param_values);
+ /* Extend full peel max insns parameter for x86. */
+ maybe_set_param_value (PARAM_MAX_COMPLETELY_PEELED_INSNS,
+ 120,
+ opts->x_param_values,
+ opts_set->x_param_values);
+
/* Enable sw prefetching at -O3 for CPUS that prefetching is helpful. */
if (opts->x_flag_prefetch_loop_arrays < 0
&& HAVE_prefetch
On Mon, Oct 13, 2014 at 4:23 PM, Jan Hubicka <hubicka@ucw.cz> wrote:
>> On Fri, Oct 10, 2014 at 5:40 PM, Evgeny Stupachenko <evstupac@gmail.com> wrote:
>> > Hi,
>> >
>> > The patch increase PARAM_MAX_COMPLETELY_PEELED_INSNS for CPUs with
>> > high branch cost.
>> > Bootstrap and make check are in progress.
>> > The patch boosts (up to 2,5 times improve) several benchmarks compiled
>> > with "-Ofast" on Silvermont
>> > Spec2000:
>> > +5% gain on 173.applu
>> > +1% gain on 255.vortex
>> >
>> > Is it ok for trunk when pass bootstrap and make check?
>>
>> This is only a 20% increase - from 100 to 120. I would instead suggest
>> to explore doing this change unconditionally if it helps that much.
>
> Agreed, I think the value of 100 was set decade ago by Zdenek and me completely
> artifically. I do not recall any serious tuning of this flag.
>
> Note that I plan to update
> https://gcc.gnu.org/ml/gcc-patches/2013-11/msg02270.html to current tree so
> PARAM_MAX_COMPLETELY_PEELED_INSNS will be used at gimple level rather than tree
> changing its meaning somewhat.
>
> Perhaps I could try to find time this or next week to update the patch so we do
> not need to do the tuning twice.
>
> Honza
>
>>
>> Richard.
>>
>> > Thanks,
>> > Evgeny
>> >
>> > 2014-10-10 Evgeny Stupachenko <evstupac@gmail.com>
>> > * config/i386/i386.c (ix86_option_override_internal): Increase
>> > PARAM_MAX_COMPLETELY_PEELED_INSNS for CPUs with high branch cost.
>> > * config/i386/i386.h (TARGET_HIGH_BRANCH_COST): New.
>> > * config/i386/x86-tune.def (X86_TUNE_HIGH_BRANCH_COST): Indicates
>> > CPUs with high branch cost.
>> >
>> > diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
>> > index 6337aa5..5ac10eb 100644
>> > --- a/gcc/config/i386/i386.c
>> > +++ b/gcc/config/i386/i386.c
>> > @@ -4081,6 +4081,14 @@ ix86_option_override_internal (bool main_args_p,
>> > opts->x_param_values,
>> > opts_set->x_param_values);
>> >
>> > + /* Extend full peel max insns parameter for CPUs with high branch cost. */
>> > + if (TARGET_HIGH_BRANCH_COST)
>> > + maybe_set_param_value (PARAM_MAX_COMPLETELY_PEELED_INSNS,
>> > + 120,
>> > + opts->x_param_values,
>> > + opts_set->x_param_values);
>> > +
>> > +
>> > /* Enable sw prefetching at -O3 for CPUS that prefetching is helpful. */
>> > if (opts->x_flag_prefetch_loop_arrays < 0
>> > && HAVE_prefetch
>> > diff --git a/gcc/config/i386/i386.h b/gcc/config/i386/i386.h
>> > index 2c64162..da0c57b 100644
>> > --- a/gcc/config/i386/i386.h
>> > +++ b/gcc/config/i386/i386.h
>> > @@ -415,6 +415,7 @@ extern unsigned char ix86_tune_features[X86_TUNE_LAST];
>> > #define TARGET_INTER_UNIT_CONVERSIONS \
>> > ix86_tune_features[X86_TUNE_INTER_UNIT_CONVERSIONS]
>> > #define TARGET_FOUR_JUMP_LIMIT ix86_tune_features[X86_TUNE_FOUR_JUMP_LIMIT]
>> > +#define TARGET_HIGH_BRANCH_COST
>> > ix86_tune_features[X86_TUNE_HIGH_BRANCH_COST]
>> > #define TARGET_SCHEDULE ix86_tune_features[X86_TUNE_SCHEDULE]
>> > #define TARGET_USE_BT ix86_tune_features[X86_TUNE_USE_BT]
>> > #define TARGET_USE_INCDEC ix86_tune_features[X86_TUNE_USE_INCDEC]
>> > diff --git a/gcc/config/i386/x86-tune.def b/gcc/config/i386/x86-tune.def
>> > index b6b210e..04d8bf8 100644
>> > --- a/gcc/config/i386/x86-tune.def
>> > +++ b/gcc/config/i386/x86-tune.def
>> > @@ -208,6 +208,11 @@ DEF_TUNE (X86_TUNE_FOUR_JUMP_LIMIT, "four_jump_limit",
>> > m_PPRO | m_P4_NOCONA | m_BONNELL | m_SILVERMONT | m_INTEL |
>> > m_ATHLON_K8 | m_AMDFAM10)
>> >
>> > +/* X86_TUNE_HIGH_BRANCH_COST: Some CPUs have higher branch cost. This could be
>> > + used to tune unroll, if-cvt, inline... heuristics. */
>> > +DEF_TUNE (X86_TUNE_HIGH_BRANCH_COST, "high_branch_cost",
>> > + m_BONNELL | m_SILVERMONT | m_INTEL)
>> > +
>> > /*****************************************************************************/
>> > /* Integer instruction selection tuning */
>> > /*****************************************************************************/
On Mon, Oct 13, 2014 at 3:23 PM, Jan Hubicka <hubicka@ucw.cz> wrote:
>> On Fri, Oct 10, 2014 at 5:40 PM, Evgeny Stupachenko <evstupac@gmail.com> wrote:
>> > Hi,
>> >
>> > The patch increase PARAM_MAX_COMPLETELY_PEELED_INSNS for CPUs with
>> > high branch cost.
>> > Bootstrap and make check are in progress.
>> > The patch boosts (up to 2,5 times improve) several benchmarks compiled
>> > with "-Ofast" on Silvermont
>> > Spec2000:
>> > +5% gain on 173.applu
>> > +1% gain on 255.vortex
>> >
>> > Is it ok for trunk when pass bootstrap and make check?
>>
>> This is only a 20% increase - from 100 to 120. I would instead suggest
>> to explore doing this change unconditionally if it helps that much.
>
> Agreed, I think the value of 100 was set decade ago by Zdenek and me completely
> artifically. I do not recall any serious tuning of this flag.
>
> Note that I plan to update
> https://gcc.gnu.org/ml/gcc-patches/2013-11/msg02270.html to current tree so
> PARAM_MAX_COMPLETELY_PEELED_INSNS will be used at gimple level rather than tree
> changing its meaning somewhat.
>
> Perhaps I could try to find time this or next week to update the patch so we do
> not need to do the tuning twice.
>
> Honza
>
>>
>> Richard.
>>
>> > Thanks,
>> > Evgeny
>> >
>> > 2014-10-10 Evgeny Stupachenko <evstupac@gmail.com>
>> > * config/i386/i386.c (ix86_option_override_internal): Increase
>> > PARAM_MAX_COMPLETELY_PEELED_INSNS for CPUs with high branch cost.
>> > * config/i386/i386.h (TARGET_HIGH_BRANCH_COST): New.
>> > * config/i386/x86-tune.def (X86_TUNE_HIGH_BRANCH_COST): Indicates
>> > CPUs with high branch cost.
>> >
>> > diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
>> > index 6337aa5..5ac10eb 100644
>> > --- a/gcc/config/i386/i386.c
>> > +++ b/gcc/config/i386/i386.c
>> > @@ -4081,6 +4081,14 @@ ix86_option_override_internal (bool main_args_p,
>> > opts->x_param_values,
>> > opts_set->x_param_values);
>> >
>> > + /* Extend full peel max insns parameter for CPUs with high branch cost. */
>> > + if (TARGET_HIGH_BRANCH_COST)
>> > + maybe_set_param_value (PARAM_MAX_COMPLETELY_PEELED_INSNS,
>> > + 120,
>> > + opts->x_param_values,
>> > + opts_set->x_param_values);
>> > +
>> > +
>> > /* Enable sw prefetching at -O3 for CPUS that prefetching is helpful. */
>> > if (opts->x_flag_prefetch_loop_arrays < 0
>> > && HAVE_prefetch
>> > diff --git a/gcc/config/i386/i386.h b/gcc/config/i386/i386.h
>> > index 2c64162..da0c57b 100644
>> > --- a/gcc/config/i386/i386.h
>> > +++ b/gcc/config/i386/i386.h
>> > @@ -415,6 +415,7 @@ extern unsigned char ix86_tune_features[X86_TUNE_LAST];
>> > #define TARGET_INTER_UNIT_CONVERSIONS \
>> > ix86_tune_features[X86_TUNE_INTER_UNIT_CONVERSIONS]
>> > #define TARGET_FOUR_JUMP_LIMIT ix86_tune_features[X86_TUNE_FOUR_JUMP_LIMIT]
>> > +#define TARGET_HIGH_BRANCH_COST
>> > ix86_tune_features[X86_TUNE_HIGH_BRANCH_COST]
>> > #define TARGET_SCHEDULE ix86_tune_features[X86_TUNE_SCHEDULE]
>> > #define TARGET_USE_BT ix86_tune_features[X86_TUNE_USE_BT]
>> > #define TARGET_USE_INCDEC ix86_tune_features[X86_TUNE_USE_INCDEC]
>> > diff --git a/gcc/config/i386/x86-tune.def b/gcc/config/i386/x86-tune.def
>> > index b6b210e..04d8bf8 100644
>> > --- a/gcc/config/i386/x86-tune.def
>> > +++ b/gcc/config/i386/x86-tune.def
>> > @@ -208,6 +208,11 @@ DEF_TUNE (X86_TUNE_FOUR_JUMP_LIMIT, "four_jump_limit",
>> > m_PPRO | m_P4_NOCONA | m_BONNELL | m_SILVERMONT | m_INTEL |
>> > m_ATHLON_K8 | m_AMDFAM10)
>> >
>> > +/* X86_TUNE_HIGH_BRANCH_COST: Some CPUs have higher branch cost. This could be
>> > + used to tune unroll, if-cvt, inline... heuristics. */
>> > +DEF_TUNE (X86_TUNE_HIGH_BRANCH_COST, "high_branch_cost",
>> > + m_BONNELL | m_SILVERMONT | m_INTEL)
>> > +
>> > /*****************************************************************************/
>> > /* Integer instruction selection tuning */
>> > /*****************************************************************************/
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