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).
A better patch would have been to adjust via the target hooks for
unroll adjust.
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)
