On Mon, 28 Oct 2019, Jiufu Guo wrote:
> Richard Biener <rguent...@suse.de> writes:
>
> > On Fri, 25 Oct 2019, Jiufu Guo wrote:
> >
> >> Hi,
> >>
> >> In PR88760, there are a few disscussion about improve or tune unroller for
> >> targets. And we would agree to enable unroller for small loops at O2 first.
> >> And we could see performance improvement(~10%) for below code:
> >> ```
> >> subroutine foo (i, i1, block)
> >> integer :: i, i1
> >> integer :: block(9, 9, 9)
> >> block(i:9,1,i1) = block(i:9,1,i1) - 10
> >> end subroutine foo
> >>
> >> ```
> >> This kind of code occurs a few times in exchange2 benchmark.
> >>
> >> Similar C code:
> >> ```
> >> for (i = 0; i < n; i++)
> >> arr[i] = arr[i] - 10;
> >> ```
> >>
> >> On powerpc64le, for O2 , enable -funroll-loops and limit
> >> PARAM_MAX_UNROLL_TIMES=2 and PARAM_MAX_UNROLLED_INSNS=20, we can see >2%
> >> overall improvement for SPEC2017.
> >
> > Note the behavior with LTO will be surprising (and generally when
> > functions are compiled with different -O level via the optimize
> > attribute). It's a bad idea to base --param values on the value
> > of a global optimization option that can be set per function
> > (see PR92046).
>
> Thanks Richard,
> --param values are not save per function. If using different method to
> compile and link (e.g. compiling with -O2 -flto, linking with -flto -O2
> -funroll-loops --param xxx), compiling and linking would use different
> --param value.
Yes, and more so if you have most units commpiled with -O2 but one
with -O3 then you get implicit "global" -O3 at link-time and thus
-O3 --param settings for all -O2 compiled functions.
> >
> > A better patch would have been to adjust via the target hooks for
> > unroll adjust.
> Yeap. And in unroll adjust target hook, we can do fine tunning with more
> heuristic thougths. I'm going to refine this way.
Thanks. Note enabling unrolling at -O2 for the target like you did
should work OK for LTO (even if some units explicitely disable it
via -fno-unroll-loop).
Richard.
> Thanks again.
>
> Jiufu Guo
> BR.
>
> >
> > Thanks,
> > Richard.
> >
> >> This patch is only for rs6000 in which we see visible performance
> >> improvement.
> >>
> >> Bootstrapped on powerpc64le, and cases are updated. Is this ok for trunk?
> >>
> >> Jiufu Guo
> >> BR
> >>
> >>
> >> gcc/
> >> 2019-10-25 Jiufu Guo <guoji...@linux.ibm.com>
> >>
> >> PR tree-optimization/88760
> >> * config/rs6000/rs6000-common.c (rs6000_option_optimization_table): for
> >> O2, enable funroll-loops.
> >> * config/rs6000/rs6000.c (rs6000_option_override_internal): if unroller
> >> is enabled throught O2, set constrains to PARAM_MAX_UNROLL_TIMES=2 and
> >> PARAM_MAX_UNROLLED_INSNS=20 for small loops.
> >>
> >> gcc.testsuite/
> >> 2019-10-25 Jiufu Guo <guoji...@linux.ibm.com>
> >>
> >> PR tree-optimization/88760
> >> * gcc.target/powerpc/small-loop-unroll.c: New test.
> >> * c-c++-common/tsan/thread_leak2.c: Update test.
> >> * gcc.dg/pr59643.c: Update test.
> >> * gcc.target/powerpc/loop_align.c: Update test.
> >> * gcc.target/powerpc/ppc-fma-1.c: Update test.
> >> * gcc.target/powerpc/ppc-fma-2.c: Update test.
> >> * gcc.target/powerpc/ppc-fma-3.c: Update test.
> >> * gcc.target/powerpc/ppc-fma-4.c: Update test.
> >> * gcc.target/powerpc/pr78604.c: Update test.
> >>
> >> ---
> >> gcc/common/config/rs6000/rs6000-common.c | 1 +
> >> gcc/config/rs6000/rs6000.c | 20
> >> ++++++++++++++++++++
> >> gcc/testsuite/c-c++-common/tsan/thread_leak2.c | 1 +
> >> gcc/testsuite/gcc.dg/pr59643.c | 1 +
> >> gcc/testsuite/gcc.target/powerpc/loop_align.c | 2 +-
> >> gcc/testsuite/gcc.target/powerpc/ppc-fma-1.c | 2 +-
> >> gcc/testsuite/gcc.target/powerpc/ppc-fma-2.c | 2 +-
> >> gcc/testsuite/gcc.target/powerpc/ppc-fma-3.c | 2 +-
> >> gcc/testsuite/gcc.target/powerpc/ppc-fma-4.c | 2 +-
> >> gcc/testsuite/gcc.target/powerpc/pr78604.c | 2 +-
> >> gcc/testsuite/gcc.target/powerpc/small-loop-unroll.c | 13 +++++++++++++
> >> 11 files changed, 42 insertions(+), 6 deletions(-)
> >> create mode 100644 gcc/testsuite/gcc.target/powerpc/small-loop-unroll.c
> >>
> >> diff --git a/gcc/common/config/rs6000/rs6000-common.c
> >> b/gcc/common/config/rs6000/rs6000-common.c
> >> index 4b0c205..b947196 100644
> >> --- a/gcc/common/config/rs6000/rs6000-common.c
> >> +++ b/gcc/common/config/rs6000/rs6000-common.c
> >> @@ -35,6 +35,7 @@ static const struct default_options
> >> rs6000_option_optimization_table[] =
> >> { OPT_LEVELS_ALL, OPT_fsplit_wide_types_early, NULL, 1 },
> >> /* Enable -fsched-pressure for first pass instruction scheduling. */
> >> { OPT_LEVELS_1_PLUS, OPT_fsched_pressure, NULL, 1 },
> >> + { OPT_LEVELS_2_PLUS, OPT_funroll_loops, NULL, 1 },
> >> { OPT_LEVELS_NONE, 0, NULL, 0 }
> >> };
> >>
> >> diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
> >> index a129137d..9a8ff9a 100644
> >> --- a/gcc/config/rs6000/rs6000.c
> >> +++ b/gcc/config/rs6000/rs6000.c
> >> @@ -4540,6 +4540,26 @@ rs6000_option_override_internal (bool global_init_p)
> >> global_options.x_param_values,
> >> global_options_set.x_param_values);
> >>
> >> + /* unroll very small loops 2 time if no -funroll-loops. */
> >> + if (!global_options_set.x_flag_unroll_loops
> >> + && !global_options_set.x_flag_unroll_all_loops)
> >> + {
> >> + maybe_set_param_value (PARAM_MAX_UNROLL_TIMES, 2,
> >> + global_options.x_param_values,
> >> + global_options_set.x_param_values);
> >> +
> >> + maybe_set_param_value (PARAM_MAX_UNROLLED_INSNS, 20,
> >> + global_options.x_param_values,
> >> + global_options_set.x_param_values);
> >> +
> >> + /* If fweb or frename-registers are not specificed in command-line,
> >> + do not turn them on implicitly. */
> >> + if (!global_options_set.x_flag_web)
> >> + global_options.x_flag_web = 0;
> >> + if (!global_options_set.x_flag_rename_registers)
> >> + global_options.x_flag_rename_registers = 0;
> >> + }
> >> +
> >> /* If using typedef char *va_list, signal that
> >> __builtin_va_start (&ap, 0) can be optimized to
> >> ap = __builtin_next_arg (0). */
> >> diff --git a/gcc/testsuite/c-c++-common/tsan/thread_leak2.c
> >> b/gcc/testsuite/c-c++-common/tsan/thread_leak2.c
> >> index c9b8046..17aa5c6 100644
> >> --- a/gcc/testsuite/c-c++-common/tsan/thread_leak2.c
> >> +++ b/gcc/testsuite/c-c++-common/tsan/thread_leak2.c
> >> @@ -1,4 +1,5 @@
> >> /* { dg-shouldfail "tsan" } */
> >> +/* { dg-additional-options "-fno-unroll-loops" { target { powerpc-*-*
> >> powerpc64-*-* powerpc64le-*-* } } } */
> >>
> >> #include <pthread.h>
> >> #include <unistd.h>
> >> diff --git a/gcc/testsuite/gcc.dg/pr59643.c
> >> b/gcc/testsuite/gcc.dg/pr59643.c
> >> index de78d60..3aef439 100644
> >> --- a/gcc/testsuite/gcc.dg/pr59643.c
> >> +++ b/gcc/testsuite/gcc.dg/pr59643.c
> >> @@ -1,6 +1,7 @@
> >> /* PR tree-optimization/59643 */
> >> /* { dg-do compile } */
> >> /* { dg-options "-O3 -fdump-tree-pcom-details" } */
> >> +/* { dg-additional-options "-fno-unroll-loops" { target { powerpc-*-*
> >> powerpc64-*-* powerpc64le-*-* } } } */
> >>
> >> void
> >> foo (double *a, double *b, double *c, double d, double e, int n)
> >> diff --git a/gcc/testsuite/gcc.target/powerpc/loop_align.c
> >> b/gcc/testsuite/gcc.target/powerpc/loop_align.c
> >> index ebe3782..ef67f77 100644
> >> --- a/gcc/testsuite/gcc.target/powerpc/loop_align.c
> >> +++ b/gcc/testsuite/gcc.target/powerpc/loop_align.c
> >> @@ -1,6 +1,6 @@
> >> /* { dg-do compile { target { powerpc*-*-* } } } */
> >> /* { dg-skip-if "" { powerpc*-*-darwin* powerpc-ibm-aix* } } */
> >> -/* { dg-options "-O2 -mdejagnu-cpu=power7 -falign-functions=16" } */
> >> +/* { dg-options "-O2 -mdejagnu-cpu=power7 -falign-functions=16
> >> -fno-unroll-loops" } */
> >> /* { dg-final { scan-assembler ".p2align 5" } } */
> >>
> >> void f(double *a, double *b, double *c, unsigned long n) {
> >> diff --git a/gcc/testsuite/gcc.target/powerpc/ppc-fma-1.c
> >> b/gcc/testsuite/gcc.target/powerpc/ppc-fma-1.c
> >> index b4945e6..2a5b92c 100644
> >> --- a/gcc/testsuite/gcc.target/powerpc/ppc-fma-1.c
> >> +++ b/gcc/testsuite/gcc.target/powerpc/ppc-fma-1.c
> >> @@ -1,7 +1,7 @@
> >> /* { dg-do compile { target { powerpc*-*-* } } } */
> >> /* { dg-skip-if "" { powerpc*-*-darwin* } } */
> >> /* { dg-require-effective-target powerpc_vsx_ok } */
> >> -/* { dg-options "-O3 -ftree-vectorize -mdejagnu-cpu=power7 -ffast-math" }
> >> */
> >> +/* { dg-options "-O3 -ftree-vectorize -mdejagnu-cpu=power7 -ffast-math
> >> -fno-unroll-loops" } */
> >> /* { dg-final { scan-assembler-times "xvmadd" 4 } } */
> >> /* { dg-final { scan-assembler-times "xsmadd\|fmadd\ " 2 } } */
> >> /* { dg-final { scan-assembler-times "fmadds" 2 } } */
> >> diff --git a/gcc/testsuite/gcc.target/powerpc/ppc-fma-2.c
> >> b/gcc/testsuite/gcc.target/powerpc/ppc-fma-2.c
> >> index 5ed630a..bf2c67f 100644
> >> --- a/gcc/testsuite/gcc.target/powerpc/ppc-fma-2.c
> >> +++ b/gcc/testsuite/gcc.target/powerpc/ppc-fma-2.c
> >> @@ -1,7 +1,7 @@
> >> /* { dg-do compile { target { powerpc*-*-* } } } */
> >> /* { dg-skip-if "" { powerpc*-*-darwin* } } */
> >> /* { dg-require-effective-target powerpc_vsx_ok } */
> >> -/* { dg-options "-O3 -ftree-vectorize -mdejagnu-cpu=power7 -ffast-math
> >> -ffp-contract=off" } */
> >> +/* { dg-options "-O3 -ftree-vectorize -mdejagnu-cpu=power7 -ffast-math
> >> -ffp-contract=off -fno-unroll-loops" } */
> >> /* { dg-final { scan-assembler-times "xvmadd" 2 } } */
> >> /* { dg-final { scan-assembler-times "xsmadd\|fmadd\ " 1 } } */
> >> /* { dg-final { scan-assembler-times "fmadds" 1 } } */
> >> diff --git a/gcc/testsuite/gcc.target/powerpc/ppc-fma-3.c
> >> b/gcc/testsuite/gcc.target/powerpc/ppc-fma-3.c
> >> index ef252b3..8608116 100644
> >> --- a/gcc/testsuite/gcc.target/powerpc/ppc-fma-3.c
> >> +++ b/gcc/testsuite/gcc.target/powerpc/ppc-fma-3.c
> >> @@ -2,7 +2,7 @@
> >> /* { dg-skip-if "" { powerpc*-*-darwin* } } */
> >> /* { dg-require-effective-target powerpc_altivec_ok } */
> >> /* { dg-require-effective-target powerpc_fprs } */
> >> -/* { dg-options "-O3 -ftree-vectorize -mdejagnu-cpu=power6 -maltivec
> >> -ffast-math" } */
> >> +/* { dg-options "-O3 -ftree-vectorize -mdejagnu-cpu=power6 -maltivec
> >> -ffast-math -fno-unroll-loops" } */
> >> /* { dg-final { scan-assembler-times "vmaddfp" 2 } } */
> >> /* { dg-final { scan-assembler-times "fmadd " 2 } } */
> >> /* { dg-final { scan-assembler-times "fmadds" 2 } } */
> >> diff --git a/gcc/testsuite/gcc.target/powerpc/ppc-fma-4.c
> >> b/gcc/testsuite/gcc.target/powerpc/ppc-fma-4.c
> >> index c2eaf1a..291c2ee 100644
> >> --- a/gcc/testsuite/gcc.target/powerpc/ppc-fma-4.c
> >> +++ b/gcc/testsuite/gcc.target/powerpc/ppc-fma-4.c
> >> @@ -2,7 +2,7 @@
> >> /* { dg-skip-if "" { powerpc*-*-darwin* } } */
> >> /* { dg-require-effective-target powerpc_altivec_ok } */
> >> /* { dg-require-effective-target powerpc_fprs } */
> >> -/* { dg-options "-O3 -ftree-vectorize -mdejagnu-cpu=power6 -maltivec
> >> -ffast-math -ffp-contract=off" } */
> >> +/* { dg-options "-O3 -ftree-vectorize -mdejagnu-cpu=power6 -maltivec
> >> -ffast-math -ffp-contract=off -fno-unroll-loops" } */
> >> /* { dg-final { scan-assembler-times "vmaddfp" 1 } } */
> >> /* { dg-final { scan-assembler-times "fmadd " 1 } } */
> >> /* { dg-final { scan-assembler-times "fmadds" 1 } } */
> >> diff --git a/gcc/testsuite/gcc.target/powerpc/pr78604.c
> >> b/gcc/testsuite/gcc.target/powerpc/pr78604.c
> >> index 76d8945..35bfdb3 100644
> >> --- a/gcc/testsuite/gcc.target/powerpc/pr78604.c
> >> +++ b/gcc/testsuite/gcc.target/powerpc/pr78604.c
> >> @@ -1,7 +1,7 @@
> >> /* { dg-do compile { target { powerpc*-*-* } } } */
> >> /* { dg-skip-if "" { powerpc*-*-darwin* } } */
> >> /* { dg-require-effective-target powerpc_p8vector_ok } */
> >> -/* { dg-options "-mdejagnu-cpu=power8 -O2 -ftree-vectorize
> >> -fdump-tree-vect-details" } */
> >> +/* { dg-options "-mdejagnu-cpu=power8 -O2 -ftree-vectorize
> >> -fdump-tree-vect-details -fno-unroll-loops" } */
> >>
> >> #ifndef SIZE
> >> #define SIZE 1024
> >> diff --git a/gcc/testsuite/gcc.target/powerpc/small-loop-unroll.c
> >> b/gcc/testsuite/gcc.target/powerpc/small-loop-unroll.c
> >> new file mode 100644
> >> index 0000000..888ea50b
> >> --- /dev/null
> >> +++ b/gcc/testsuite/gcc.target/powerpc/small-loop-unroll.c
> >> @@ -0,0 +1,13 @@
> >> +/* { dg-do compile } */
> >> +/* { dg-options "-O2 -fdump-rtl-loop2_unroll" } */
> >> +
> >> +void __attribute__ ((noinline)) foo(int n, int *arr)
> >> +{
> >> + int i;
> >> + for (i = 0; i < n; i++)
> >> + arr[i] = arr[i] - 10;
> >> +}
> >> +/* { dg-final { scan-rtl-dump-times "Unrolled loop 1 times" 1
> >> "loop2_unroll" } } */
> >> +/* { dg-final { scan-assembler-times "lwz" 3 } } */
> >> +/* { dg-final { scan-assembler-times "stw" 3 } } */
> >> +
> >>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)
