On Thu, Jun 3, 2021 at 12:39 AM Uros Bizjak <ubiz...@gmail.com> wrote: > > On Thu, Jun 3, 2021 at 5:49 AM H.J. Lu <hjl.to...@gmail.com> wrote: > > > > Update move expanders to convert the CONST_WIDE_INT operand to vector > > broadcast from a byte with AVX2. Add ix86_gen_scratch_sse_rtx to > > return a scratch SSE register which won't increase stack alignment > > requirement and blocks transformation by the combine pass. > > Using fixed scratch reg is just too hackish for my taste. The
It was recommended to use hard register for things like this: https://gcc.gnu.org/pipermail/gcc-patches/2021-May/569945.html > expansion is OK to emit some optimized sequence, but the approach to > use fixed reg to bypass stack alignment functionality and combine is > not. > > Perhaps a new insn pattern should be introduced, e.g. > > (define_insn_and_split "" > [(set (match_opreand:V 0 "memory_operand" "=m,m") > (vec_duplicate:V > (match_operand:S 2 "reg_or_0_operand" "r,C")) > (clobber (match_scratch:V 1 "=x"))] > > and split it at some appropriate point. I will give it a try. Thanks. > Uros. > > > > > A small benchmark: > > > > https://gitlab.com/x86-benchmarks/microbenchmark/-/tree/memset/broadcast > > > > shows that broadcast is a little bit faster on Intel Core i7-8559U: > > > > $ make > > gcc -g -I. -O2 -c -o test.o test.c > > gcc -g -c -o memory.o memory.S > > gcc -g -c -o broadcast.o broadcast.S > > gcc -o test test.o memory.o broadcast.o > > ./test > > memory : 99333 > > broadcast: 97208 > > $ > > > > broadcast is also smaller: > > > > $ size memory.o broadcast.o > > text data bss dec hex filename > > 132 0 0 132 84 memory.o > > 122 0 0 122 7a broadcast.o > > $ > > > > gcc/ > > > > PR target/100865 > > * config/i386/i386-expand.c (ix86_expand_vector_init_duplicate): > > New prototype. > > (ix86_byte_broadcast): New function. > > (ix86_convert_const_wide_int_to_broadcast): Likewise. > > (ix86_expand_move): Try ix86_convert_const_wide_int_to_broadcast > > if mode size is 16 bytes or bigger. > > (ix86_expand_vector_move): Try > > ix86_convert_const_wide_int_to_broadcast. > > * config/i386/i386-protos.h (ix86_gen_scratch_sse_rtx): New > > prototype. > > * config/i386/i386.c (ix86_minimum_incoming_stack_boundary): Add > > an argument to ignore stack_alignment_estimated. It is passed > > as false by default. > > (ix86_gen_scratch_sse_rtx): New function. > > > > gcc/testsuite/ > > > > PR target/100865 > > * gcc.target/i386/pr100865-1.c: New test. > > * gcc.target/i386/pr100865-2.c: Likewise. > > * gcc.target/i386/pr100865-3.c: Likewise. > > * gcc.target/i386/pr100865-4.c: Likewise. > > * gcc.target/i386/pr100865-5.c: Likewise. > > --- > > gcc/config/i386/i386-expand.c | 103 ++++++++++++++++++--- > > gcc/config/i386/i386-protos.h | 2 + > > gcc/config/i386/i386.c | 50 +++++++++- > > gcc/testsuite/gcc.target/i386/pr100865-1.c | 13 +++ > > gcc/testsuite/gcc.target/i386/pr100865-2.c | 14 +++ > > gcc/testsuite/gcc.target/i386/pr100865-3.c | 15 +++ > > gcc/testsuite/gcc.target/i386/pr100865-4.c | 16 ++++ > > gcc/testsuite/gcc.target/i386/pr100865-5.c | 17 ++++ > > 8 files changed, 215 insertions(+), 15 deletions(-) > > create mode 100644 gcc/testsuite/gcc.target/i386/pr100865-1.c > > create mode 100644 gcc/testsuite/gcc.target/i386/pr100865-2.c > > create mode 100644 gcc/testsuite/gcc.target/i386/pr100865-3.c > > create mode 100644 gcc/testsuite/gcc.target/i386/pr100865-4.c > > create mode 100644 gcc/testsuite/gcc.target/i386/pr100865-5.c > > > > diff --git a/gcc/config/i386/i386-expand.c b/gcc/config/i386/i386-expand.c > > index 4185f58eed5..658adafa269 100644 > > --- a/gcc/config/i386/i386-expand.c > > +++ b/gcc/config/i386/i386-expand.c > > @@ -93,6 +93,9 @@ along with GCC; see the file COPYING3. If not see > > #include "i386-builtins.h" > > #include "i386-expand.h" > > > > +static bool ix86_expand_vector_init_duplicate (bool, machine_mode, rtx, > > + rtx); > > + > > /* Split one or more double-mode RTL references into pairs of half-mode > > references. The RTL can be REG, offsettable MEM, integer constant, or > > CONST_DOUBLE. "operands" is a pointer to an array of double-mode RTLs > > to > > @@ -190,6 +193,65 @@ ix86_expand_clear (rtx dest) > > emit_insn (tmp); > > } > > > > +/* Return a byte value which V can be broadcasted from. Otherwise, > > + return INT_MAX. */ > > + > > +static int > > +ix86_byte_broadcast (HOST_WIDE_INT v) > > +{ > > + wide_int val = wi::uhwi (v, HOST_BITS_PER_WIDE_INT); > > + int byte_broadcast = wi::extract_uhwi (val, 0, BITS_PER_UNIT); > > + for (unsigned int i = BITS_PER_UNIT; > > + i < HOST_BITS_PER_WIDE_INT; > > + i += BITS_PER_UNIT) > > + { > > + int byte = wi::extract_uhwi (val, i, BITS_PER_UNIT); > > + if (byte_broadcast != byte) > > + return INT_MAX; > > + } > > + return byte_broadcast; > > +} > > + > > +/* Convert the CONST_WIDE_INT operand OP to broadcast in MODE. */ > > + > > +static rtx > > +ix86_convert_const_wide_int_to_broadcast (machine_mode mode, rtx op) > > +{ > > + rtx target = nullptr; > > + > > + /* Convert CONST_WIDE_INT to broadcast only if vector broadcast is > > + available. */ > > + if (!TARGET_AVX2 || !CONST_WIDE_INT_P (op)) > > + return target; > > + > > + HOST_WIDE_INT val = CONST_WIDE_INT_ELT (op, 0); > > + int byte_broadcast = ix86_byte_broadcast (val); > > + > > + if (byte_broadcast == INT_MAX) > > + return target; > > + > > + /* Check if OP1 can be broadcasted from VAL. */ > > + for (int i = 1; i < CONST_WIDE_INT_NUNITS (op); i++) > > + if (val != CONST_WIDE_INT_ELT (op, i)) > > + return target; > > + > > + unsigned int nunits = GET_MODE_SIZE (mode) / GET_MODE_SIZE (QImode); > > + machine_mode vector_mode; > > + if (!mode_for_vector (QImode, nunits).exists (&vector_mode)) > > + gcc_unreachable (); > > + target = ix86_gen_scratch_sse_rtx (vector_mode, true); > > + rtx byte = GEN_INT ((char) byte_broadcast); > > + if (!ix86_expand_vector_init_duplicate (false, vector_mode, target, > > + byte)) > > + gcc_unreachable (); > > + if (REGNO (target) < FIRST_PSEUDO_REGISTER) > > + target = gen_rtx_REG (mode, REGNO (target)); > > + else > > + target = convert_to_mode (mode, target, 1); > > + > > + return target; > > +} > > + > > void > > ix86_expand_move (machine_mode mode, rtx operands[]) > > { > > @@ -347,20 +409,29 @@ ix86_expand_move (machine_mode mode, rtx operands[]) > > && optimize) > > op1 = copy_to_mode_reg (mode, op1); > > > > - if (can_create_pseudo_p () > > - && CONST_DOUBLE_P (op1)) > > + if (can_create_pseudo_p ()) > > { > > - /* If we are loading a floating point constant to a register, > > - force the value to memory now, since we'll get better code > > - out the back end. */ > > + if (CONST_DOUBLE_P (op1)) > > + { > > + /* If we are loading a floating point constant to a > > + register, force the value to memory now, since we'll > > + get better code out the back end. */ > > > > - op1 = validize_mem (force_const_mem (mode, op1)); > > - if (!register_operand (op0, mode)) > > + op1 = validize_mem (force_const_mem (mode, op1)); > > + if (!register_operand (op0, mode)) > > + { > > + rtx temp = gen_reg_rtx (mode); > > + emit_insn (gen_rtx_SET (temp, op1)); > > + emit_move_insn (op0, temp); > > + return; > > + } > > + } > > + else if (GET_MODE_SIZE (mode) >= 16) > > { > > - rtx temp = gen_reg_rtx (mode); > > - emit_insn (gen_rtx_SET (temp, op1)); > > - emit_move_insn (op0, temp); > > - return; > > + rtx tmp = ix86_convert_const_wide_int_to_broadcast > > + (GET_MODE (op0), op1); > > + if (tmp != nullptr) > > + op1 = tmp; > > } > > } > > } > > @@ -407,7 +478,15 @@ ix86_expand_vector_move (machine_mode mode, rtx > > operands[]) > > op1 = simplify_gen_subreg (mode, r, imode, SUBREG_BYTE (op1)); > > } > > else > > - op1 = validize_mem (force_const_mem (mode, op1)); > > + { > > + machine_mode mode = GET_MODE (op0); > > + rtx tmp = ix86_convert_const_wide_int_to_broadcast > > + (mode, op1); > > + if (tmp == nullptr) > > + op1 = validize_mem (force_const_mem (mode, op1)); > > + else > > + op1 = tmp; > > + } > > } > > > > /* We need to check memory alignment for SSE mode since attribute > > diff --git a/gcc/config/i386/i386-protos.h b/gcc/config/i386/i386-protos.h > > index 7782cf1163f..01b3775df92 100644 > > --- a/gcc/config/i386/i386-protos.h > > +++ b/gcc/config/i386/i386-protos.h > > @@ -50,6 +50,8 @@ extern void ix86_reset_previous_fndecl (void); > > > > extern bool ix86_using_red_zone (void); > > > > +extern rtx ix86_gen_scratch_sse_rtx (machine_mode, bool); > > + > > extern unsigned int ix86_regmode_natural_size (machine_mode); > > #ifdef RTX_CODE > > extern int standard_80387_constant_p (rtx); > > diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c > > index 04649b42122..3595fb5778e 100644 > > --- a/gcc/config/i386/i386.c > > +++ b/gcc/config/i386/i386.c > > @@ -415,7 +415,8 @@ static unsigned int split_stack_prologue_scratch_regno > > (void); > > static bool i386_asm_output_addr_const_extra (FILE *, rtx); > > > > static bool ix86_can_inline_p (tree, tree); > > -static unsigned int ix86_minimum_incoming_stack_boundary (bool); > > +static unsigned int ix86_minimum_incoming_stack_boundary (bool, > > + bool = false); > > > > > > /* Whether -mtune= or -march= were specified */ > > @@ -7232,7 +7233,8 @@ find_drap_reg (void) > > /* Return minimum incoming stack alignment. */ > > > > static unsigned int > > -ix86_minimum_incoming_stack_boundary (bool sibcall) > > +ix86_minimum_incoming_stack_boundary (bool sibcall, > > + bool ignore_estimated) > > { > > unsigned int incoming_stack_boundary; > > > > @@ -7247,7 +7249,8 @@ ix86_minimum_incoming_stack_boundary (bool sibcall) > > estimated stack alignment is 128bit. */ > > else if (!sibcall > > && ix86_force_align_arg_pointer > > - && crtl->stack_alignment_estimated == 128) > > + && (ignore_estimated > > + || crtl->stack_alignment_estimated == 128)) > > incoming_stack_boundary = MIN_STACK_BOUNDARY; > > else > > incoming_stack_boundary = ix86_default_incoming_stack_boundary; > > @@ -23061,6 +23064,47 @@ ix86_optab_supported_p (int op, machine_mode > > mode1, machine_mode, > > } > > } > > > > +/* Return a scratch register in MODE for vector load and store. If > > + CONSTANT_BROADCAST is true, it is used to hold constant broadcast > > + result. */ > > + > > +rtx > > +ix86_gen_scratch_sse_rtx (machine_mode mode, bool constant_broadcast) > > +{ > > + bool need_hard_reg = false; > > + > > + /* NB: Choose a hard scratch SSE register: > > + 1. Avoid increasing stack alignment requirement. > > + 2. for constant broadcast in 64-bit mode, avoid transformation by > > + the combine pass. > > + */ > > + if (GET_MODE_SIZE (mode) >= 16 > > + && !COMPLEX_MODE_P (mode) > > + && (SCALAR_INT_MODE_P (mode) || VECTOR_MODE_P (mode))) > > + { > > + if (constant_broadcast > > + && TARGET_64BIT > > + && GET_MODE_SIZE (mode) == 16) > > + need_hard_reg = true; > > + else > > + { > > + unsigned int incoming_stack_boundary > > + = ix86_minimum_incoming_stack_boundary (false, true); > > + if (GET_MODE_ALIGNMENT (mode) > incoming_stack_boundary) > > + need_hard_reg = true; > > + } > > + } > > + > > + rtx target; > > + if (need_hard_reg) > > + target = gen_rtx_REG (mode, (TARGET_64BIT > > + ? LAST_REX_SSE_REG > > + : LAST_SSE_REG)); > > + else > > + target = gen_reg_rtx (mode); > > + return target; > > +} > > + > > /* Address space support. > > > > This is not "far pointers" in the 16-bit sense, but an easy way > > diff --git a/gcc/testsuite/gcc.target/i386/pr100865-1.c > > b/gcc/testsuite/gcc.target/i386/pr100865-1.c > > new file mode 100644 > > index 00000000000..6c3097fb2a6 > > --- /dev/null > > +++ b/gcc/testsuite/gcc.target/i386/pr100865-1.c > > @@ -0,0 +1,13 @@ > > +/* { dg-do compile { target { ! ia32 } } } */ > > +/* { dg-options "-O2 -march=x86-64" } */ > > + > > +extern char *dst; > > + > > +void > > +foo (void) > > +{ > > + __builtin_memset (dst, 3, 16); > > +} > > + > > +/* { dg-final { scan-assembler-times "movdqa\[ \\t\]+\[^\n\]*%xmm" 1 } } */ > > +/* { dg-final { scan-assembler-times "movups\[\\t \]%xmm\[0-9\]+, > > \\(%\[\^,\]+\\)" 1 } } */ > > diff --git a/gcc/testsuite/gcc.target/i386/pr100865-2.c > > b/gcc/testsuite/gcc.target/i386/pr100865-2.c > > new file mode 100644 > > index 00000000000..17efe2d72a3 > > --- /dev/null > > +++ b/gcc/testsuite/gcc.target/i386/pr100865-2.c > > @@ -0,0 +1,14 @@ > > +/* { dg-do compile { target { ! ia32 } } } */ > > +/* { dg-options "-O2 -march=skylake" } */ > > + > > +extern char *dst; > > + > > +void > > +foo (void) > > +{ > > + __builtin_memset (dst, 3, 16); > > +} > > + > > +/* { dg-final { scan-assembler-times "vpbroadcastb\[\\t \]+%xmm\[0-9\]+, > > %xmm\[0-9\]+" 1 } } */ > > +/* { dg-final { scan-assembler-times "vmovdqu\[\\t \]%xmm\[0-9\]+, > > \\(%\[\^,\]+\\)" 1 } } */ > > +/* { dg-final { scan-assembler-not "vmovdqa" } } */ > > diff --git a/gcc/testsuite/gcc.target/i386/pr100865-3.c > > b/gcc/testsuite/gcc.target/i386/pr100865-3.c > > new file mode 100644 > > index 00000000000..56665d8c9b6 > > --- /dev/null > > +++ b/gcc/testsuite/gcc.target/i386/pr100865-3.c > > @@ -0,0 +1,15 @@ > > +/* { dg-do compile { target { ! ia32 } } } */ > > +/* { dg-options "-O2 -march=skylake-avx512" } */ > > + > > +extern char *dst; > > + > > +void > > +foo (void) > > +{ > > + __builtin_memset (dst, 3, 16); > > +} > > + > > +/* { dg-final { scan-assembler-times "vpbroadcastb\[\\t \]+%.*, > > %xmm\[0-9\]+" 1 } } */ > > +/* { dg-final { scan-assembler-times "vmovdqu\[\\t \]%xmm\[0-9\]+, > > \\(%\[\^,\]+\\)" 1 } } */ > > +/* { dg-final { scan-assembler-not "vpbroadcastb\[\\t \]+%xmm\[0-9\]+, > > %xmm\[0-9\]+" } } */ > > +/* { dg-final { scan-assembler-not "vmovdqa" } } */ > > diff --git a/gcc/testsuite/gcc.target/i386/pr100865-4.c > > b/gcc/testsuite/gcc.target/i386/pr100865-4.c > > new file mode 100644 > > index 00000000000..1622a06f57e > > --- /dev/null > > +++ b/gcc/testsuite/gcc.target/i386/pr100865-4.c > > @@ -0,0 +1,16 @@ > > +/* { dg-do compile { target { ! ia32 } } } */ > > +/* { dg-options "-O2 -march=skylake" } */ > > + > > +extern char array[64]; > > + > > +void > > +foo (void) > > +{ > > + int i; > > + for (i = 0; i < 64; i++) > > + array[i] = -45; > > +} > > + > > +/* { dg-final { scan-assembler-times "vpbroadcastb\[\\t \]+%xmm\[0-9\]+, > > %xmm\[0-9\]+" 1 } } */ > > +/* { dg-final { scan-assembler-times "vmovdqu\[\\t \]%xmm\[0-9\]+, " 4 } } > > */ > > +/* { dg-final { scan-assembler-not "vmovdqa" } } */ > > diff --git a/gcc/testsuite/gcc.target/i386/pr100865-5.c > > b/gcc/testsuite/gcc.target/i386/pr100865-5.c > > new file mode 100644 > > index 00000000000..66040d9f972 > > --- /dev/null > > +++ b/gcc/testsuite/gcc.target/i386/pr100865-5.c > > @@ -0,0 +1,17 @@ > > +/* { dg-do compile { target { ! ia32 } } } */ > > +/* { dg-options "-O2 -march=skylake-avx512" } */ > > + > > +extern char array[64]; > > + > > +void > > +foo (void) > > +{ > > + int i; > > + for (i = 0; i < 64; i++) > > + array[i] = -45; > > +} > > + > > +/* { dg-final { scan-assembler-times "vpbroadcastb\[\\t \]+%.*, > > %xmm\[0-9\]+" 1 } } */ > > +/* { dg-final { scan-assembler-times "vmovdqu\[\\t \]%xmm\[0-9\]+, " 4 } } > > */ > > +/* { dg-final { scan-assembler-not "vpbroadcastb\[\\t \]+%xmm\[0-9\]+, > > %xmm\[0-9\]+" } } */ > > +/* { dg-final { scan-assembler-not "vmovdqa" } } */ > > -- > > 2.31.1 > > -- H.J.
