Simplify memcpy and memset inline strategies to avoid branches for
-mtune=generic:
1. With MOVE_RATIO and CLEAR_RATIO == 17, GCC will use integer/vector
load and store for up to 16 * 16 (256) bytes when the data size is
fixed and known.
2. Inline only if data size is known to be <= 256.
a. Use "rep movsb/stosb" with simple code sequence if the data size
is a constant.
b. Use loop if data size is not a constant.
3. Use memcpy/memset library function if data size is unknown or > 256.
Here is the performance data from March 2021 when the original patch was
submitted. With -march=x86-64 -O2,
1. On Ice Lake processor,
Performance impacts on SPEC CPU 2017:
500.perlbench_r 0.51%
502.gcc_r 0.55%
505.mcf_r 0.38%
520.omnetpp_r -0.74%
523.xalancbmk_r -0.35%
525.x264_r 2.99%
531.deepsjeng_r -0.17%
541.leela_r -0.98%
548.exchange2_r 0.89%
557.xz_r 0.70%
Geomean 0.37%
503.bwaves_r 0.04%
507.cactuBSSN_r -0.01%
508.namd_r -0.45%
510.parest_r -0.09%
511.povray_r -1.37%
519.lbm_r 0.00%
521.wrf_r -2.56%
526.blender_r -0.01%
527.cam4_r -0.05%
538.imagick_r 0.36%
544.nab_r 0.08%
549.fotonik3d_r -0.06%
554.roms_r 0.05%
Geomean -0.34%
Significant impacts on eembc benchmarks:
eembc/nnet_test 14.85%
eembc/mp2decoddata2 13.57%
2. On Cascadelake processor,
Performance impacts on SPEC CPU 2017:
500.perlbench_r -0.02%
502.gcc_r 0.10%
505.mcf_r -1.14%
520.omnetpp_r -0.22%
523.xalancbmk_r 0.21%
525.x264_r 0.94%
531.deepsjeng_r -0.37%
541.leela_r -0.46%
548.exchange2_r -0.40%
557.xz_r 0.60%
Geomean -0.08%
503.bwaves_r -0.50%
507.cactuBSSN_r 0.05%
508.namd_r -0.02%
510.parest_r 0.09%
511.povray_r -1.35%
519.lbm_r 0.00%
521.wrf_r -0.03%
526.blender_r -0.83%
527.cam4_r 1.23%
538.imagick_r 0.97%
544.nab_r -0.02%
549.fotonik3d_r -0.12%
554.roms_r 0.55%
Geomean 0.00%
Significant impacts on eembc benchmarks:
eembc/nnet_test 9.90%
eembc/mp2decoddata2 16.42%
eembc/textv2data3 -4.86%
eembc/qos 12.90%
3. On Znver3 processor,
Performance impacts on SPEC CPU 2017:
500.perlbench_r -0.96%
502.gcc_r -1.06%
505.mcf_r -0.01%
520.omnetpp_r -1.45%
523.xalancbmk_r 2.89%
525.x264_r 4.98%
531.deepsjeng_r 0.18%
541.leela_r -1.54%
548.exchange2_r -1.25%
557.xz_r -0.01%
Geomean 0.16%
503.bwaves_r 0.04%
507.cactuBSSN_r 0.85%
508.namd_r -0.13%
510.parest_r 0.39%
511.povray_r 0.00%
519.lbm_r 0.00%
521.wrf_r 0.28%
526.blender_r -0.10%
527.cam4_r -0.58%
538.imagick_r 0.69%
544.nab_r -0.04%
549.fotonik3d_r -0.04%
554.roms_r 0.40%
Geomean 0.15%
Significant impacts on eembc benchmarks:
eembc/aifftr01 13.95%
eembc/idctrn01 8.41%
eembc/nnet_test 30.25%
eembc/mp2decoddata2 5.05%
eembc/textv2data3 6.43%
eembc/qos -5.79%
Code size differences are:
SPEC CPU 2017 with -march=x86-64 -O2
before after diff
500.perlbench_r 2226178 2226866 0.031%
502.gcc_r 9250727 9253711 0.032%
505.mcf_r 21653 21730 0.356%
520.omnetpp_r 2131839 2133259 0.067%
523.xalancbmk_r 4695615 4696039 0.009%
525.x264_r 490651 490659 0.002%
531.deepsjeng_r 85832 86056 0.261%
541.leela_r 169005 165021 -2.357%
548.exchange2_r 70189 69901 -0.410%
557.xz_r 196314 197506 0.607%
503.bwaves_r 37430 37878 1.197%
507.cactuBSSN_r 3550438 3550622 0.005%
508.namd_r 880455 880519 0.007%
510.parest_r 8561798 8586781 0.292%
511.povray_r 1058268 1058068 -0.019%
519.lbm_r 16415 16415 0.000%
521.wrf_r 23197011 23202227 0.022%
526.blender_r 10408951 10422175 0.127%
527.cam4_r 18979378 18983410 0.021%
538.imagick_r 1999052 1998780 -0.014%
544.nab_r 191416 191688 0.142%
549.fotonik3d_r 384499 384507 0.002%
554.roms_r 853869 854277 0.048%
SPEC CPU 2017 with -march=x86-64 -Ofast -funroll-loops
before after diff
500.perlbench_r 2940860 2946588 0.195%
502.gcc_r 11577095 11581975 0.042%
505.mcf_r 64469 64546 0.119%
520.omnetpp_r 2549149 2550669 0.060%
523.xalancbmk_r 6992956 6993236 0.004%
525.x264_r 836325 837125 0.096%
531.deepsjeng_r 137280 137464 0.134%
541.leela_r 277370 268817 -3.084%
548.exchange2_r 298361 297569 -0.265%
557.xz_r 244154 244994 0.344%
503.bwaves_r 55414 55414 0.000%
507.cactuBSSN_r 7902089 7902417 0.004%
508.namd_r 1703404 1703468 0.004%
510.parest_r 13184149 13195957 0.090%
511.povray_r 1403980 1403612 -0.026%
519.lbm_r 18284 18284 0.000%
521.wrf_r 35707507 35724635 0.048%
526.blender_r 14098264 14113040 0.105%
527.cam4_r 23818819 23887715 0.289%
538.imagick_r 3131670 3131206 -0.015%
544.nab_r 322493 323597 0.342%
549.fotonik3d_r 778635 778643 0.001%
554.roms_r 1977171 1981707 0.229%
gcc/
PR target/102294
PR target/119596
* config/i386/x86-tune-costs.h (generic_memcpy): Updated.
(generic_memset): Likewise.
(generic_cost): Change CLEAR_RATIO to 17.
* config/i386/x86-tune.def (X86_TUNE_PREFER_KNOWN_REP_MOVSB_STOSB):
Add m_GENERIC.
gcc/testsuite/
PR target/102294
PR target/119596
* gcc.target/i386/auto-init-padding-3.c: Expect XMM stores.
* gcc.target/i386/auto-init-padding-9.c: Likewise.
* gcc.target/i386/memcpy-strategy-12.c: New test.
* gcc.target/i386/memcpy-strategy-13.c: Likewise.
* gcc.target/i386/memset-strategy-10.c: Likewise.
* gcc.target/i386/memset-strategy-11.c: Likewise.
* gcc.target/i386/memset-strategy-12.c: Likewise.
* gcc.target/i386/mvc17.c: Fail with "rep mov"
* gcc.target/i386/shrink_wrap_1.c: Also pass
-mmemset-strategy=rep_8byte:-1:align.
* gcc.target/i386/sw-1.c: Also pass -mstringop-strategy=rep_byte.
Signed-off-by: H.J. Lu <hjl.to...@gmail.com>
---
gcc/config/i386/x86-tune-costs.h | 31 ++++++++++++-------
gcc/config/i386/x86-tune.def | 2 +-
.../gcc.target/i386/auto-init-padding-3.c | 7 ++---
.../gcc.target/i386/auto-init-padding-9.c | 8 ++---
.../gcc.target/i386/memcpy-strategy-12.c | 9 ++++++
.../gcc.target/i386/memcpy-strategy-13.c | 11 +++++++
.../gcc.target/i386/memset-strategy-10.c | 11 +++++++
.../gcc.target/i386/memset-strategy-11.c | 9 ++++++
.../gcc.target/i386/memset-strategy-12.c | 15 +++++++++
gcc/testsuite/gcc.target/i386/mvc17.c | 2 +-
gcc/testsuite/gcc.target/i386/shrink_wrap_1.c | 2 +-
gcc/testsuite/gcc.target/i386/sw-1.c | 2 +-
12 files changed, 84 insertions(+), 25 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/i386/memcpy-strategy-12.c
create mode 100644 gcc/testsuite/gcc.target/i386/memcpy-strategy-13.c
create mode 100644 gcc/testsuite/gcc.target/i386/memset-strategy-10.c
create mode 100644 gcc/testsuite/gcc.target/i386/memset-strategy-11.c
create mode 100644 gcc/testsuite/gcc.target/i386/memset-strategy-12.c
diff --git a/gcc/config/i386/x86-tune-costs.h b/gcc/config/i386/x86-tune-costs.h
index 7c8cb738d7c..7d749b5108e 100644
--- a/gcc/config/i386/x86-tune-costs.h
+++ b/gcc/config/i386/x86-tune-costs.h
@@ -3814,19 +3814,28 @@ struct processor_costs shijidadao_cost = {
-/* Generic should produce code tuned for Core-i7 (and newer chips)
- and btver1 (and newer chips). */
+/* Generic should produce code tuned for Haswell (and newer chips)
+ and znver1 (and newer chips). NB: rep_prefix_1_byte is used only
+ for known size. */
static stringop_algs generic_memcpy[2] = {
- {libcall, {{32, loop, false}, {8192, rep_prefix_4_byte, false},
- {-1, libcall, false}}},
- {libcall, {{32, loop, false}, {8192, rep_prefix_8_byte, false},
- {-1, libcall, false}}}};
+ {libcall,
+ {{256, rep_prefix_1_byte, true},
+ {256, loop, false},
+ {-1, libcall, false}}},
+ {libcall,
+ {{256, rep_prefix_1_byte, true},
+ {256, loop, false},
+ {-1, libcall, false}}}};
static stringop_algs generic_memset[2] = {
- {libcall, {{32, loop, false}, {8192, rep_prefix_4_byte, false},
- {-1, libcall, false}}},
- {libcall, {{32, loop, false}, {8192, rep_prefix_8_byte, false},
- {-1, libcall, false}}}};
+ {libcall,
+ {{256, rep_prefix_1_byte, true},
+ {256, loop, false},
+ {-1, libcall, false}}},
+ {libcall,
+ {{256, rep_prefix_1_byte, true},
+ {256, loop, false},
+ {-1, libcall, false}}}};
static const
struct processor_costs generic_cost = {
{
@@ -3883,7 +3892,7 @@ struct processor_costs generic_cost = {
COSTS_N_INSNS (1), /* cost of movzx */
8, /* "large" insn */
17, /* MOVE_RATIO */
- 6, /* CLEAR_RATIO */
+ 17, /* CLEAR_RATIO */
{6, 6, 6}, /* cost of loading integer registers
in QImode, HImode and SImode.
Relative to reg-reg move (2). */
diff --git a/gcc/config/i386/x86-tune.def b/gcc/config/i386/x86-tune.def
index c857e769b60..c3635c71d06 100644
--- a/gcc/config/i386/x86-tune.def
+++ b/gcc/config/i386/x86-tune.def
@@ -329,7 +329,7 @@ DEF_TUNE (X86_TUNE_SINGLE_STRINGOP, "single_stringop",
m_386 | m_P4_NOCONA)
DEF_TUNE (X86_TUNE_PREFER_KNOWN_REP_MOVSB_STOSB,
"prefer_known_rep_movsb_stosb",
m_SKYLAKE | m_CORE_HYBRID | m_CORE_ATOM | m_TREMONT | m_CORE_AVX512
- | m_ZHAOXIN)
+ | m_ZHAOXIN | m_GENERIC)
/* X86_TUNE_MISALIGNED_MOVE_STRING_PRO_EPILOGUES: Enable generation of
compact prologues and epilogues by issuing a misaligned moves. This
diff --git a/gcc/testsuite/gcc.target/i386/auto-init-padding-3.c
b/gcc/testsuite/gcc.target/i386/auto-init-padding-3.c
index 7c20a28508f..a12069a039d 100644
--- a/gcc/testsuite/gcc.target/i386/auto-init-padding-3.c
+++ b/gcc/testsuite/gcc.target/i386/auto-init-padding-3.c
@@ -23,8 +23,5 @@ int foo ()
return var.four.internal1;
}
-/* { dg-final { scan-assembler "movl\t\\\$0," } } */
-/* { dg-final { scan-assembler "movl\t\\\$16," { target { ! ia32 } } } } */
-/* { dg-final { scan-assembler "rep stosq" { target { ! ia32 } } } } */
-/* { dg-final { scan-assembler "movl\t\\\$32," { target ia32 } } } */
-/* { dg-final { scan-assembler "rep stosl" { target ia32 } } } */
+/* { dg-final { scan-assembler-times "pxor\t%xmm0, %xmm0" 1 } } */
+/* { dg-final { scan-assembler-times "movaps\t%xmm0, " 8 } } */
diff --git a/gcc/testsuite/gcc.target/i386/auto-init-padding-9.c
b/gcc/testsuite/gcc.target/i386/auto-init-padding-9.c
index a87b68b255b..404b53c5e7a 100644
--- a/gcc/testsuite/gcc.target/i386/auto-init-padding-9.c
+++ b/gcc/testsuite/gcc.target/i386/auto-init-padding-9.c
@@ -18,8 +18,6 @@ int foo ()
return var[2].four;
}
-/* { dg-final { scan-assembler "movl\t\\\$0," } } */
-/* { dg-final { scan-assembler "movl\t\\\$20," { target { ! ia32 } } } } */
-/* { dg-final { scan-assembler "rep stosq" { target { ! ia32 } } } } */
-/* { dg-final { scan-assembler "movl\t\\\$40," { target ia32} } } */
-/* { dg-final { scan-assembler "rep stosl" { target ia32 } } } */
+/* { dg-final { scan-assembler-times "pxor\t%xmm0, %xmm0" 1 } } */
+/* { dg-final { scan-assembler-times "movaps\t%xmm0, " 10 { target { ! ia32 }
} } } */
+/* { dg-final { scan-assembler-times "movups\t%xmm0, " 10 { target ia32 } } }
*/
diff --git a/gcc/testsuite/gcc.target/i386/memcpy-strategy-12.c
b/gcc/testsuite/gcc.target/i386/memcpy-strategy-12.c
new file mode 100644
index 00000000000..e9998b70ab2
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/memcpy-strategy-12.c
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -mtune=generic -mno-sse" } */
+/* { dg-final { scan-assembler "rep movsb" } } */
+
+void
+foo (char *dest, char *src)
+{
+ __builtin_memcpy (dest, src, 249);
+}
diff --git a/gcc/testsuite/gcc.target/i386/memcpy-strategy-13.c
b/gcc/testsuite/gcc.target/i386/memcpy-strategy-13.c
new file mode 100644
index 00000000000..109bd675a51
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/memcpy-strategy-13.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -mtune=generic -mno-avx" } */
+/* { dg-final { scan-assembler "jmp\tmemcpy" { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler "call\tmemcpy" { target ia32 } } } */
+/* { dg-final { scan-assembler-not "rep movsb" } } */
+
+void
+foo (char *dest, char *src)
+{
+ __builtin_memcpy (dest, src, 257);
+}
diff --git a/gcc/testsuite/gcc.target/i386/memset-strategy-10.c
b/gcc/testsuite/gcc.target/i386/memset-strategy-10.c
new file mode 100644
index 00000000000..685d6e5a5c2
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/memset-strategy-10.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -mtune=generic -mno-avx" } */
+/* { dg-final { scan-assembler "jmp\tmemset" { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler "call\tmemset" { target ia32 } } } */
+/* { dg-final { scan-assembler-not "rep stosb" } } */
+
+void
+foo (char *dest)
+{
+ __builtin_memset (dest, 0, 257);
+}
diff --git a/gcc/testsuite/gcc.target/i386/memset-strategy-11.c
b/gcc/testsuite/gcc.target/i386/memset-strategy-11.c
new file mode 100644
index 00000000000..61ee463a8cf
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/memset-strategy-11.c
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -mtune=generic -mno-sse" } */
+/* { dg-final { scan-assembler "rep stosb" } } */
+
+void
+foo (char *dest)
+{
+ __builtin_memset (dest, 0, 253);
+}
diff --git a/gcc/testsuite/gcc.target/i386/memset-strategy-12.c
b/gcc/testsuite/gcc.target/i386/memset-strategy-12.c
new file mode 100644
index 00000000000..c53bce52e17
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/memset-strategy-12.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -mtune=generic -mno-sse" } */
+/* { dg-final { scan-assembler-not "jmp\tmemset" } } */
+/* { dg-final { scan-assembler-not "rep stosb" } } */
+
+struct foo
+{
+ char buf[41];
+};
+
+void
+zero(struct foo *f)
+{
+ __builtin_memset(f->buf, 0, sizeof(f->buf));
+}
diff --git a/gcc/testsuite/gcc.target/i386/mvc17.c
b/gcc/testsuite/gcc.target/i386/mvc17.c
index 8b83c1aecb3..dbf35ac36dc 100644
--- a/gcc/testsuite/gcc.target/i386/mvc17.c
+++ b/gcc/testsuite/gcc.target/i386/mvc17.c
@@ -1,7 +1,7 @@
/* { dg-do compile } */
/* { dg-require-ifunc "" } */
/* { dg-options "-O2 -march=x86-64" } */
-/* { dg-final { scan-assembler-times "rep mov" 1 } } */
+/* { dg-final { scan-assembler-not "rep mov" } } */
__attribute__((target_clones("default","arch=icelake-server")))
void
diff --git a/gcc/testsuite/gcc.target/i386/shrink_wrap_1.c
b/gcc/testsuite/gcc.target/i386/shrink_wrap_1.c
index 4b286671e90..30b82ab695a 100644
--- a/gcc/testsuite/gcc.target/i386/shrink_wrap_1.c
+++ b/gcc/testsuite/gcc.target/i386/shrink_wrap_1.c
@@ -1,5 +1,5 @@
/* { dg-do compile { target { ! ia32 } } } */
-/* { dg-options "-O2 -fdump-rtl-pro_and_epilogue -fno-stack-protector" } */
+/* { dg-options "-O2 -mmemset-strategy=rep_8byte:-1:align
-fdump-rtl-pro_and_epilogue -fno-stack-protector" } */
enum machine_mode
{
diff --git a/gcc/testsuite/gcc.target/i386/sw-1.c
b/gcc/testsuite/gcc.target/i386/sw-1.c
index b0432279644..14db3cee206 100644
--- a/gcc/testsuite/gcc.target/i386/sw-1.c
+++ b/gcc/testsuite/gcc.target/i386/sw-1.c
@@ -1,5 +1,5 @@
/* { dg-do compile } */
-/* { dg-options "-O2 -mtune=generic -fshrink-wrap -fdump-rtl-pro_and_epilogue
-fno-stack-protector" } */
+/* { dg-options "-O2 -mtune=generic -mstringop-strategy=rep_byte -fshrink-wrap
-fdump-rtl-pro_and_epilogue -fno-stack-protector" } */
/* { dg-additional-options "-mno-avx" { target ia32 } } */
/* { dg-skip-if "No shrink-wrapping preformed" { x86_64-*-mingw* } } */
--
2.49.0
