On Wed, Jul 14, 2021 at 10:34 AM liuhongt <hongtao....@intel.com> wrote:
>
> By optimizing vector movement to broadcast in ix86_expand_vector_move
> during pass_expand, pass_reload/LRA can automatically generate an avx512
> embedded broadcast, pass_cpb is not needed.
>
> Considering that in the absence of avx512f, broadcast from memory is
> still slightly faster than loading the entire memory, so always enable
> broadcast.
>
> benchmark:
> https://gitlab.com/x86-benchmarks/microbenchmark/-/tree/vaddps/broadcast
>
> The performance diff
>
> strategy : cycles
> memory : 1046611188
> memory : 1255420817
> memory : 1044720793
> memory : 1253414145
> average : 1097868397
>
> broadcast : 1044430688
> broadcast : 1044477630
> broadcast : 1253554603
> broadcast : 1044561934
> average : 1096756213
>
> But however broadcast has larger size.
>
> the size diff
>
> size broadcast.o
> text data bss dec hex filename
> 137 0 0 137 89 broadcast.o
>
> size memory.o
> text data bss dec hex filename
> 115 0 0 115 73 memory.o
>
> Bootstrapped and regtested on x86_64-linux-gnu{-m32,}
>
> gcc/ChangeLog:
>
> * config/i386/i386-expand.c
> (ix86_broadcast_from_integer_constant): Rename to ..
> (ix86_broadcast_from_constant): .. this, and extend it to
> handle float mode.
> (ix86_expand_vector_move): Extend to float mode.
> * config/i386/i386-features.c
> (replace_constant_pool_with_broadcast): Remove.
> (remove_partial_avx_dependency_gate): Ditto.
> (constant_pool_broadcast): Ditto.
> (class pass_constant_pool_broadcast): Ditto.
> (make_pass_constant_pool_broadcast): Ditto.
> (remove_partial_avx_dependency): Adjust gate.
> * config/i386/i386-passes.def: Remove pass_constant_pool_broadcast.
> * config/i386/i386-protos.h
> (make_pass_constant_pool_broadcast): Remove.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/i386/fuse-caller-save-xmm.c: Adjust testcase.
> ---
> gcc/config/i386/i386-expand.c | 29 +++-
> gcc/config/i386/i386-features.c | 157 +-----------------
> gcc/config/i386/i386-passes.def | 1 -
> gcc/config/i386/i386-protos.h | 1 -
> .../gcc.target/i386/fuse-caller-save-xmm.c | 2 +-
> 5 files changed, 26 insertions(+), 164 deletions(-)
>
> diff --git a/gcc/config/i386/i386-expand.c b/gcc/config/i386/i386-expand.c
> index 69ea79e6123..ba870145acd 100644
> --- a/gcc/config/i386/i386-expand.c
> +++ b/gcc/config/i386/i386-expand.c
> @@ -453,8 +453,10 @@ ix86_expand_move (machine_mode mode, rtx operands[])
> emit_insn (gen_rtx_SET (op0, op1));
> }
>
> +/* OP is a memref of CONST_VECTOR, return scalar constant mem
> + if CONST_VECTOR is a vec_duplicate, else return NULL. */
> static rtx
> -ix86_broadcast_from_integer_constant (machine_mode mode, rtx op)
> +ix86_broadcast_from_constant (machine_mode mode, rtx op)
> {
> int nunits = GET_MODE_NUNITS (mode);
> if (nunits < 2)
> @@ -462,7 +464,8 @@ ix86_broadcast_from_integer_constant (machine_mode mode,
> rtx op)
>
> /* Don't use integer vector broadcast if we can't move from GPR to SSE
> register directly. */
> - if (!TARGET_INTER_UNIT_MOVES_TO_VEC)
> + if (!TARGET_INTER_UNIT_MOVES_TO_VEC
> + && INTEGRAL_MODE_P (mode))
> return nullptr;
>
> /* Convert CONST_VECTOR to a non-standard SSE constant integer
> @@ -470,12 +473,17 @@ ix86_broadcast_from_integer_constant (machine_mode
> mode, rtx op)
> if (!(TARGET_AVX2
> || (TARGET_AVX
> && (GET_MODE_INNER (mode) == SImode
> - || GET_MODE_INNER (mode) == DImode)))
> + || GET_MODE_INNER (mode) == DImode))
> + || FLOAT_MODE_P (mode))
> || standard_sse_constant_p (op, mode))
> return nullptr;
>
> - /* Don't broadcast from a 64-bit integer constant in 32-bit mode. */
> - if (GET_MODE_INNER (mode) == DImode && !TARGET_64BIT)
> + /* Don't broadcast from a 64-bit integer constant in 32-bit mode.
> + We can still put 64-bit integer constant in memory when
> + avx512 embed broadcast is available. */
> + if (GET_MODE_INNER (mode) == DImode && !TARGET_64BIT
> + && (!TARGET_AVX512F
> + || (GET_MODE_SIZE (mode) < 64 && !TARGET_AVX512VL)))
> return nullptr;
>
> if (GET_MODE_INNER (mode) == TImode)
> @@ -561,17 +569,20 @@ ix86_expand_vector_move (machine_mode mode, rtx
> operands[])
>
> if (can_create_pseudo_p ()
> && GET_MODE_SIZE (mode) >= 16
> - && GET_MODE_CLASS (mode) == MODE_VECTOR_INT
> + && VECTOR_MODE_P (mode)
> && (MEM_P (op1)
> && SYMBOL_REF_P (XEXP (op1, 0))
> && CONSTANT_POOL_ADDRESS_P (XEXP (op1, 0))))
> {
> - rtx first = ix86_broadcast_from_integer_constant (mode, op1);
> + rtx first = ix86_broadcast_from_constant (mode, op1);
> if (first != nullptr)
> {
> /* Broadcast to XMM/YMM/ZMM register from an integer
> - constant. */
> - op1 = ix86_gen_scratch_sse_rtx (mode);
> + constant or scalar mem. */
> + op1 = gen_reg_rtx (mode);
I've changed ix86_gen_scratch_sse_rtx to gen_reg_rtx to let LRA/reload
make the final decision for register usage, would that make sense?
w/o that, hard register used here will prevent LRA/reload combine (set
op1 (vec_duplicate: mem)) and (add (op1, op2)) to (add (op1,
vec_duplicate: mem))
> + if (FLOAT_MODE_P (mode)
> + || (!TARGET_64BIT && GET_MODE_INNER (mode) == DImode))
> + first = force_const_mem (GET_MODE_INNER (mode), first);
> bool ok = ix86_expand_vector_init_duplicate (false, mode,
> op1, first);
> gcc_assert (ok);
> diff --git a/gcc/config/i386/i386-features.c b/gcc/config/i386/i386-features.c
> index cbd430a2ecf..d9c6652d1c9 100644
> --- a/gcc/config/i386/i386-features.c
> +++ b/gcc/config/i386/i386-features.c
> @@ -2136,81 +2136,6 @@ make_pass_insert_endbr_and_patchable_area
> (gcc::context *ctxt)
> return new pass_insert_endbr_and_patchable_area (ctxt);
> }
>
> -/* Replace all one-value const vector that are referenced by SYMBOL_REFs in x
> - with embedded broadcast. i.e.transform
> -
> - vpaddq .LC0(%rip), %zmm0, %zmm0
> - ret
> - .LC0:
> - .quad 3
> - .quad 3
> - .quad 3
> - .quad 3
> - .quad 3
> - .quad 3
> - .quad 3
> - .quad 3
> -
> - to
> -
> - vpaddq .LC0(%rip){1to8}, %zmm0, %zmm0
> - ret
> - .LC0:
> - .quad 3 */
> -static void
> -replace_constant_pool_with_broadcast (rtx_insn *insn)
> -{
> - subrtx_ptr_iterator::array_type array;
> - FOR_EACH_SUBRTX_PTR (iter, array, &PATTERN (insn), ALL)
> - {
> - rtx *loc = *iter;
> - rtx x = *loc;
> - rtx broadcast_mem, vec_dup, constant, first;
> - machine_mode mode;
> -
> - /* Constant pool. */
> - if (!MEM_P (x)
> - || !SYMBOL_REF_P (XEXP (x, 0))
> - || !CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
> - continue;
> -
> - /* Const vector. */
> - mode = GET_MODE (x);
> - if (!VECTOR_MODE_P (mode))
> - return;
> - constant = get_pool_constant (XEXP (x, 0));
> - if (GET_CODE (constant) != CONST_VECTOR)
> - return;
> -
> - /* There could be some rtx like
> - (mem/u/c:V16QI (symbol_ref/u:DI ("*.LC1")))
> - but with "*.LC1" refer to V2DI constant vector. */
> - if (GET_MODE (constant) != mode)
> - {
> - constant = simplify_subreg (mode, constant, GET_MODE (constant), 0);
> - if (constant == NULL_RTX || GET_CODE (constant) != CONST_VECTOR)
> - return;
> - }
> - first = XVECEXP (constant, 0, 0);
> -
> - for (int i = 1; i < GET_MODE_NUNITS (mode); ++i)
> - {
> - rtx tmp = XVECEXP (constant, 0, i);
> - /* Vector duplicate value. */
> - if (!rtx_equal_p (tmp, first))
> - return;
> - }
> -
> - /* Replace with embedded broadcast. */
> - broadcast_mem = force_const_mem (GET_MODE_INNER (mode), first);
> - vec_dup = gen_rtx_VEC_DUPLICATE (mode, broadcast_mem);
> - validate_change (insn, loc, vec_dup, 0);
> -
> - /* At most 1 memory_operand in an insn. */
> - return;
> - }
> -}
> -
> /* At entry of the nearest common dominator for basic blocks with
> conversions, generate a single
> vxorps %xmmN, %xmmN, %xmmN
> @@ -2249,10 +2174,6 @@ remove_partial_avx_dependency (void)
> if (!NONDEBUG_INSN_P (insn))
> continue;
>
> - /* Handle AVX512 embedded broadcast here to save compile time. */
> - if (TARGET_AVX512F)
> - replace_constant_pool_with_broadcast (insn);
> -
> set = single_set (insn);
> if (!set)
> continue;
> @@ -2384,16 +2305,6 @@ remove_partial_avx_dependency (void)
> return 0;
> }
>
> -static bool
> -remove_partial_avx_dependency_gate ()
> -{
> - return (TARGET_AVX
> - && TARGET_SSE_PARTIAL_REG_DEPENDENCY
> - && TARGET_SSE_MATH
> - && optimize
> - && optimize_function_for_speed_p (cfun));
> -}
> -
> namespace {
>
> const pass_data pass_data_remove_partial_avx_dependency =
> @@ -2419,7 +2330,11 @@ public:
> /* opt_pass methods: */
> virtual bool gate (function *)
> {
> - return remove_partial_avx_dependency_gate ();
> + return (TARGET_AVX
> + && TARGET_SSE_PARTIAL_REG_DEPENDENCY
> + && TARGET_SSE_MATH
> + && optimize
> + && optimize_function_for_speed_p (cfun));
> }
>
> virtual unsigned int execute (function *)
> @@ -2436,68 +2351,6 @@ make_pass_remove_partial_avx_dependency (gcc::context
> *ctxt)
> return new pass_remove_partial_avx_dependency (ctxt);
> }
>
> -/* For const vector having one duplicated value, there's no need to put
> - whole vector in the constant pool when target supports embedded
> broadcast. */
> -static unsigned int
> -constant_pool_broadcast (void)
> -{
> - timevar_push (TV_MACH_DEP);
> - rtx_insn *insn;
> -
> - for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
> - {
> - if (INSN_P (insn))
> - replace_constant_pool_with_broadcast (insn);
> - }
> - timevar_pop (TV_MACH_DEP);
> - return 0;
> -}
> -
> -namespace {
> -
> -const pass_data pass_data_constant_pool_broadcast =
> -{
> - RTL_PASS, /* type */
> - "cpb", /* name */
> - OPTGROUP_NONE, /* optinfo_flags */
> - TV_MACH_DEP, /* tv_id */
> - 0, /* properties_required */
> - 0, /* properties_provided */
> - 0, /* properties_destroyed */
> - 0, /* todo_flags_start */
> - TODO_df_finish, /* todo_flags_finish */
> -};
> -
> -class pass_constant_pool_broadcast : public rtl_opt_pass
> -{
> -public:
> - pass_constant_pool_broadcast (gcc::context *ctxt)
> - : rtl_opt_pass (pass_data_constant_pool_broadcast, ctxt)
> - {}
> -
> - /* opt_pass methods: */
> - virtual bool gate (function *)
> - {
> - /* Return false if rpad pass gate is true.
> - replace_constant_pool_with_broadcast is called
> - from both this pass and rpad pass. */
> - return (TARGET_AVX512F && !remove_partial_avx_dependency_gate ());
> - }
> -
> - virtual unsigned int execute (function *)
> - {
> - return constant_pool_broadcast ();
> - }
> -}; // class pass_cpb
> -
> -} // anon namespace
> -
> -rtl_opt_pass *
> -make_pass_constant_pool_broadcast (gcc::context *ctxt)
> -{
> - return new pass_constant_pool_broadcast (ctxt);
> -}
> -
> /* This compares the priority of target features in function DECL1
> and DECL2. It returns positive value if DECL1 is higher priority,
> negative value if DECL2 is higher priority and 0 if they are the
> diff --git a/gcc/config/i386/i386-passes.def b/gcc/config/i386/i386-passes.def
> index 44df00e94ac..29baf8acd0b 100644
> --- a/gcc/config/i386/i386-passes.def
> +++ b/gcc/config/i386/i386-passes.def
> @@ -33,4 +33,3 @@ along with GCC; see the file COPYING3. If not see
> INSERT_PASS_BEFORE (pass_shorten_branches, 1,
> pass_insert_endbr_and_patchable_area);
>
> INSERT_PASS_AFTER (pass_combine, 1, pass_remove_partial_avx_dependency);
> - INSERT_PASS_AFTER (pass_combine, 1, pass_constant_pool_broadcast);
> diff --git a/gcc/config/i386/i386-protos.h b/gcc/config/i386/i386-protos.h
> index 51376fcc454..07ac02aff69 100644
> --- a/gcc/config/i386/i386-protos.h
> +++ b/gcc/config/i386/i386-protos.h
> @@ -395,4 +395,3 @@ extern rtl_opt_pass
> *make_pass_insert_endbr_and_patchable_area
> (gcc::context *);
> extern rtl_opt_pass *make_pass_remove_partial_avx_dependency
> (gcc::context *);
> -extern rtl_opt_pass *make_pass_constant_pool_broadcast (gcc::context *);
> diff --git a/gcc/testsuite/gcc.target/i386/fuse-caller-save-xmm.c
> b/gcc/testsuite/gcc.target/i386/fuse-caller-save-xmm.c
> index 4deff93c1e8..b0d3dc38a0c 100644
> --- a/gcc/testsuite/gcc.target/i386/fuse-caller-save-xmm.c
> +++ b/gcc/testsuite/gcc.target/i386/fuse-caller-save-xmm.c
> @@ -6,7 +6,7 @@ typedef double v2df __attribute__((vector_size (16)));
> static v2df __attribute__((noinline))
> bar (v2df a)
> {
> - return a + (v2df){ 3.0, 3.0 };
> + return a + (v2df){ 3.0, 4.0 };
> }
>
> v2df __attribute__((noinline))
> --
> 2.18.1
>
--
BR,
Hongtao
