> Ok, Note GCC documents have been ported to sphinx, so you need to > adjust changes in invoke.texi to new sphinx files. Yes, this is the patch I'm going to check-in. Thanks. Hongtao Liu 于2022年11月14日周一 09:35写道： > > On Wed, Nov 9, 2022 at 9:29 AM Hongyu Wang wrote: > > > > > Although ix86_small_unroll_insns is coming from issue_rate, it's tuned > > > for codesize. > > > Make it exact as issue_rate and using factor * issue_width / > > > loop->ninsns may increase code size too much. > > > So I prefer to add those 2 parameters to the cost table for core > > > tunings instead of 1. > > > > Yes, here is the updated patch that changes the cost table. > > > > Bootstrapped & regrtested on x86_64-pc-linux-gnu. > > > > Ok for trunk? > Ok, Note GCC documents have been ported to sphinx, so you need to > adjust changes in invoke.texi to new sphinx files. > > > > Hongtao Liu via Gcc-patches 于2022年11月8日周二 11:05写道： > > > > > > On Mon, Nov 7, 2022 at 10:25 PM Richard Biener via Gcc-patches > > > wrote: > > > > > > > > On Wed, Nov 2, 2022 at 4:37 AM Hongyu Wang wrote: > > > > > > > > > > Hi, this is the updated patch of > > > > > https://gcc.gnu.org/pipermail/gcc-patches/2022-October/604345.html, > > > > > which uses targetm.loop_unroll_adjust as gate to enable small loop unroll. > > > > > > > > > > This patch does not change rs6000/s390 since I don't have machine to > > > > > test them, but I suppose the default behavior is the same since they > > > > > enable flag_unroll_loops at O2. > > > > > > > > > > Bootstrapped & regrtested on x86_64-pc-linux-gnu. > > > > > > > > > > Ok for trunk? > > > > > > > > > > ---------- Patch content -------- > > > > > > > > > > Modern processors has multiple way instruction decoders > > > > > For x86, icelake/zen3 has 5 uops, so for small loop with <= 4 > > > > > instructions (usually has 3 uops with a cmp/jmp pair that can be > > > > > macro-fused), the decoder would have 2 uops bubble for each iteration > > > > > and the pipeline could not be fully utilized. > > > > > > > > > > Therefore, this patch enables loop unrolling for small size loop at O2 > > > > > to fullfill the decoder as much as possible. It turns on rtl loop > > > > > unrolling when targetm.loop_unroll_adjust exists and O2 plus speed only. > > > > > In x86 backend the default behavior is to unroll small loops with less > > > > > than 4 insns by 1 time. > > > > > > > > > > This improves 548.exchange2 by 9% on icelake and 7.4% on zen3 with > > > > > 0.9% codesize increment. For other benchmarks the variants are minor > > > > > and overall codesize increased by 0.2%. > > > > > > > > > > The kernel image size increased by 0.06%, and no impact on eembc. > > > > > > > > > > gcc/ChangeLog: > > > > > > > > > > * common/config/i386/i386-common.cc (ix86_optimization_table): > > > > > Enable small loop unroll at O2 by default. > > > > > * config/i386/i386.cc (ix86_loop_unroll_adjust): Adjust unroll > > > > > factor if -munroll-only-small-loops enabled and -funroll-loops/ > > > > > -funroll-all-loops are disabled. > > > > > * config/i386/i386.opt: Add -munroll-only-small-loops, > > > > > -param=x86-small-unroll-ninsns= for loop insn limit, > > > > > -param=x86-small-unroll-factor= for unroll factor. > > > > > * doc/invoke.texi: Document -munroll-only-small-loops, > > > > > x86-small-unroll-ninsns and x86-small-unroll-factor. > > > > > * loop-init.cc (pass_rtl_unroll_loops::gate): Enable rtl > > > > > loop unrolling for -O2-speed and above if target hook > > > > > loop_unroll_adjust exists. > > > > > > > > > > gcc/testsuite/ChangeLog: > > > > > > > > > > * gcc.dg/guality/loop-1.c: Add additional option > > > > > -mno-unroll-only-small-loops. > > > > > * gcc.target/i386/pr86270.c: Add -mno-unroll-only-small-loops. > > > > > * gcc.target/i386/pr93002.c: Likewise. > > > > > --- > > > > > gcc/common/config/i386/i386-common.cc | 1 + > > > > > gcc/config/i386/i386.cc | 18 ++++++++++++++++++ > > > > > gcc/config/i386/i386.opt | 13 +++++++++++++ > > > > > gcc/doc/invoke.texi | 16 ++++++++++++++++ > > > > > gcc/loop-init.cc | 10 +++++++--- > > > > > gcc/testsuite/gcc.dg/guality/loop-1.c | 2 ++ > > > > > gcc/testsuite/gcc.target/i386/pr86270.c | 2 +- > > > > > gcc/testsuite/gcc.target/i386/pr93002.c | 2 +- > > > > > 8 files changed, 59 insertions(+), 5 deletions(-) > > > > > > > > > > diff --git a/gcc/common/config/i386/i386-common.cc b/gcc/common/config/i386/i386-common.cc > > > > > index f66bdd5a2af..c6891486078 100644 > > > > > --- a/gcc/common/config/i386/i386-common.cc > > > > > +++ b/gcc/common/config/i386/i386-common.cc > > > > > @@ -1724,6 +1724,7 @@ static const struct default_options ix86_option_optimization_table[] = > > > > > /* The STC algorithm produces the smallest code at -Os, for x86. */ > > > > > { OPT_LEVELS_2_PLUS, OPT_freorder_blocks_algorithm_, NULL, > > > > > REORDER_BLOCKS_ALGORITHM_STC }, > > > > > + { OPT_LEVELS_2_PLUS_SPEED_ONLY, OPT_munroll_only_small_loops, NULL, 1 }, > > > > > /* Turn off -fschedule-insns by default. It tends to make the > > > > > problem with not enough registers even worse. */ > > > > > { OPT_LEVELS_ALL, OPT_fschedule_insns, NULL, 0 }, > > > > > diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc > > > > > index c0f37149ed0..0f94a3b609e 100644 > > > > > --- a/gcc/config/i386/i386.cc > > > > > +++ b/gcc/config/i386/i386.cc > > > > > @@ -23827,6 +23827,24 @@ ix86_loop_unroll_adjust (unsigned nunroll, class loop *loop) > > > > > unsigned i; > > > > > unsigned mem_count = 0; > > > > > > > > > > + /* Unroll small size loop when unroll factor is not explicitly > > > > > + specified. */ > > > > > + if (!(flag_unroll_loops > > > > > + || flag_unroll_all_loops > > > > > + || loop->unroll)) > > > > > + { > > > > > + nunroll = 1; > > > > > + > > > > > + /* Any explicit -f{no-}unroll-{all-}loops turns off > > > > > + -munroll-only-small-loops. */ > > > > > + if (ix86_unroll_only_small_loops > > > > > + && !OPTION_SET_P (flag_unroll_loops)) > > > > > + if (loop->ninsns <= (unsigned) ix86_small_unroll_ninsns) > > > > > > > > either add braces or combine the two if's > > > > > > > > Otherwise the middle-end changes look OK. The target maintainers need to decide > > > > whether the two --params should be core tunings instead - I would assume that > > > > given your rationale the decode and issue widths of the core plays an important > > > > role here. That might also suggest a single parameter instead and unrolling > > > > (factor * issue_width) / loop->ninsns times instead of a static unroll_factor? > > > Although ix86_small_unroll_insns is coming from issue_rate, it's tuned > > > for codesize. > > > Make it exact as issue_rate and using factor * issue_width / > > > loop->ninsns may increase code size too much. > > > So I prefer to add those 2 parameters to the cost table for core > > > tunings instead of 1. > > > > > > > > Thanks, > > > > Richard. > > > > > > > > > + nunroll = (unsigned) ix86_small_unroll_factor; > > > > > + > > > > > + return nunroll; > > > > > + } > > > > > + > > > > > if (!TARGET_ADJUST_UNROLL) > > > > > return nunroll; > > > > > > > > > > diff --git a/gcc/config/i386/i386.opt b/gcc/config/i386/i386.opt > > > > > index 53d534f6392..6da9c8d670d 100644 > > > > > --- a/gcc/config/i386/i386.opt > > > > > +++ b/gcc/config/i386/i386.opt > > > > > @@ -1224,3 +1224,16 @@ mavxvnniint8 > > > > > Target Mask(ISA2_AVXVNNIINT8) Var(ix86_isa_flags2) Save > > > > > Support MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, AVX, AVX2 and > > > > > AVXVNNIINT8 built-in functions and code generation. > > > > > + > > > > > +munroll-only-small-loops > > > > > +Target Var(ix86_unroll_only_small_loops) Init(0) Save > > > > > +Enable conservative small loop unrolling. > > > > > + > > > > > +-param=x86-small-unroll-ninsns= > > > > > +Target Joined UInteger Var(ix86_small_unroll_ninsns) Init(4) Param > > > > > +Insturctions number limit for loop to be unrolled under > > > > > +-munroll-only-small-loops. > > > > > + > > > > > +-param=x86-small-unroll-factor= > > > > > +Target Joined UInteger Var(ix86_small_unroll_factor) Init(2) Param > > > > > +Unroll factor for -munroll-only-small-loops. > > > > > diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi > > > > > index 550aec87809..487218bd0ce 100644 > > > > > --- a/gcc/doc/invoke.texi > > > > > +++ b/gcc/doc/invoke.texi > > > > > @@ -15821,6 +15821,14 @@ The following choices of @var{name} are available on i386 and x86_64 targets: > > > > > @item x86-stlf-window-ninsns > > > > > Instructions number above which STFL stall penalty can be compensated. > > > > > > > > > > +@item x86-small-unroll-ninsns > > > > > +If -munroll-only-small-loops is enabled, only unroll loops with instruction > > > > > +count less than this parameter. The default value is 4. > > > > > + > > > > > +@item x86-small-unroll-factor > > > > > +If -munroll-only-small-loops is enabled, reset the unroll factor with this > > > > > +value. The default value is 2 which means the loop will be unrolled once. > > > > > + > > > > > @end table > > > > > > > > > > @end table > > > > > @@ -25232,6 +25240,14 @@ environments where no dynamic link is performed, like firmwares, OS > > > > > kernels, executables linked with @option{-static} or @option{-static-pie}. > > > > > @option{-mdirect-extern-access} is not compatible with @option{-fPIC} or > > > > > @option{-fpic}. > > > > > + > > > > > +@item -munroll-only-small-loops > > > > > +@itemx -mno-unroll-only-small-loops > > > > > +@opindex munroll-only-small-loops > > > > > +Controls conservative small loop unrolling. It is default enbaled by > > > > > +O2, and unrolls loop with less than 4 insns by 1 time. Explicit > > > > > +-f[no-]unroll-[all-]loops would disable this flag to avoid any > > > > > +unintended unrolling behavior that user does not want. > > > > > @end table > > > > > > > > > > @node M32C Options > > > > > diff --git a/gcc/loop-init.cc b/gcc/loop-init.cc > > > > > index b9e07973dd6..9789efa1e11 100644 > > > > > --- a/gcc/loop-init.cc > > > > > +++ b/gcc/loop-init.cc > > > > > @@ -565,9 +565,12 @@ public: > > > > > {} > > > > > > > > > > /* opt_pass methods: */ > > > > > - bool gate (function *) final override > > > > > + bool gate (function *fun) final override > > > > > { > > > > > - return (flag_unroll_loops || flag_unroll_all_loops || cfun->has_unroll); > > > > > + return (flag_unroll_loops || flag_unroll_all_loops || cfun->has_unroll > > > > > + || (targetm.loop_unroll_adjust > > > > > + && optimize >= 2 > > > > > + && optimize_function_for_speed_p (fun))); > > > > > } > > > > > > > > > > unsigned int execute (function *) final override; > > > > > @@ -583,7 +586,8 @@ pass_rtl_unroll_loops::execute (function *fun) > > > > > if (dump_file) > > > > > df_dump (dump_file); > > > > > > > > > > - if (flag_unroll_loops) > > > > > + if (flag_unroll_loops > > > > > + || targetm.loop_unroll_adjust) > > > > > flags |= UAP_UNROLL; > > > > > if (flag_unroll_all_loops) > > > > > flags |= UAP_UNROLL_ALL; > > > > > diff --git a/gcc/testsuite/gcc.dg/guality/loop-1.c b/gcc/testsuite/gcc.dg/guality/loop-1.c > > > > > index 1b1f6d32271..a32ea445a3f 100644 > > > > > --- a/gcc/testsuite/gcc.dg/guality/loop-1.c > > > > > +++ b/gcc/testsuite/gcc.dg/guality/loop-1.c > > > > > @@ -1,5 +1,7 @@ > > > > > /* { dg-do run } */ > > > > > /* { dg-options "-fno-tree-scev-cprop -fno-tree-vectorize -g" } */ > > > > > +/* { dg-additional-options "-mno-unroll-only-small-loops" { target ia32 } } */ > > > > > + > > > > > > > > > > #include "../nop.h" > > > > > > > > > > diff --git a/gcc/testsuite/gcc.target/i386/pr86270.c b/gcc/testsuite/gcc.target/i386/pr86270.c > > > > > index 81841ef5bd7..cbc9fbb0450 100644 > > > > > --- a/gcc/testsuite/gcc.target/i386/pr86270.c > > > > > +++ b/gcc/testsuite/gcc.target/i386/pr86270.c > > > > > @@ -1,5 +1,5 @@ > > > > > /* { dg-do compile } */ > > > > > -/* { dg-options "-O2" } */ > > > > > +/* { dg-options "-O2 -mno-unroll-only-small-loops" } */ > > > > > > > > > > int *a; > > > > > long len; > > > > > diff --git a/gcc/testsuite/gcc.target/i386/pr93002.c b/gcc/testsuite/gcc.target/i386/pr93002.c > > > > > index 0248fcc00a5..f75a847f75d 100644 > > > > > --- a/gcc/testsuite/gcc.target/i386/pr93002.c > > > > > +++ b/gcc/testsuite/gcc.target/i386/pr93002.c > > > > > @@ -1,6 +1,6 @@ > > > > > /* PR target/93002 */ > > > > > /* { dg-do compile } */ > > > > > -/* { dg-options "-O2" } */ > > > > > +/* { dg-options "-O2 -mno-unroll-only-small-loops" } */ > > > > > /* { dg-final { scan-assembler-not "cmp\[^\n\r]*-1" } } */ > > > > > > > > > > volatile int sink; > > > > > -- > > > > > 2.18.1 > > > > > > > > > > > > > > > > > -- > > > BR, > > > Hongtao > > > > -- > BR, > Hongtao