ac/nir: Add vote_ieq/vote_feq lowering pass.

The old vote_eq implementation supported only booleans, but now
we have to support arbitrary values, so use the read_first_invocation
intrinsic + ballot.

I took this as an opportunity to figure out how easy it was to do this
in nir instead of in the nir_to_llvm pass, and it actually turned out
pretty okay IMO. Only creating the pass is some extra code.

Reviewed-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Bas Nieuwenhuizen
2018-02-05 22:54:18 +01:00
parent c217607b65
commit 97f10934ed
5 changed files with 99 additions and 5 deletions

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@@ -44,6 +44,7 @@ AMD_COMPILER_FILES = \
common/ac_llvm_helper.cpp \
common/ac_llvm_util.c \
common/ac_llvm_util.h \
common/ac_lower_subgroups.c \
common/ac_shader_abi.h \
common/ac_shader_info.c \
common/ac_shader_info.h \

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@@ -0,0 +1,92 @@
/*
* Copyright © 2018 Google Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#include "nir/nir.h"
#include "nir/nir_builder.h"
#include "ac_nir_to_llvm.h"
static nir_ssa_def *ac_lower_subgroups_intrin(nir_builder *b, nir_intrinsic_instr *intrin)
{
switch(intrin->intrinsic) {
case nir_intrinsic_vote_ieq:
case nir_intrinsic_vote_feq: {
nir_intrinsic_instr *rfi =
nir_intrinsic_instr_create(b->shader, nir_intrinsic_read_first_invocation);
nir_ssa_dest_init(&rfi->instr, &rfi->dest,
1, intrin->src[0].ssa->bit_size, NULL);
nir_src_copy(&rfi->src[0], &intrin->src[0], rfi);
rfi->num_components = 1;
nir_ssa_def *is_ne;
if (intrin->intrinsic == nir_intrinsic_vote_feq)
is_ne = nir_fne(b, &rfi->dest.ssa, intrin->src[0].ssa);
else
is_ne = nir_ine(b, &rfi->dest.ssa, intrin->src[0].ssa);
nir_intrinsic_instr *ballot =
nir_intrinsic_instr_create(b->shader, nir_intrinsic_ballot);
nir_ssa_dest_init(&ballot->instr, &ballot->dest,
1, 64, NULL);
ballot->src[0] = nir_src_for_ssa(is_ne);
ballot->num_components = 1;
return nir_ieq(b, &ballot->dest.ssa, nir_imm_int64(b, 0));
}
default:
return NULL;
}
}
bool ac_lower_subgroups(struct nir_shader *shader)
{
bool progress = false;
nir_foreach_function(function, shader) {
if (!function->impl)
continue;
nir_builder b;
nir_builder_init(&b, function->impl);
nir_foreach_block(block, function->impl) {
nir_foreach_instr_safe(instr, block) {
if (instr->type != nir_instr_type_intrinsic)
continue;
nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
b.cursor = nir_before_instr(instr);
nir_ssa_def *lower = ac_lower_subgroups_intrin(&b, intrin);
if (!lower)
continue;
nir_ssa_def_rewrite_uses(&intrin->dest.ssa, nir_src_for_ssa(lower));
nir_instr_remove(instr);
progress = true;
}
}
}
return progress;
}

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@@ -4563,11 +4563,6 @@ static void visit_intrinsic(struct ac_nir_context *ctx,
result = LLVMBuildSExt(ctx->ac.builder, tmp, ctx->ac.i32, "");
break;
}
case nir_intrinsic_vote_ieq: {
LLVMValueRef tmp = ac_build_vote_eq(&ctx->ac, get_src(ctx, instr->src[0]));
result = LLVMBuildSExt(ctx->ac.builder, tmp, ctx->ac.i32, "");
break;
}
default:
fprintf(stderr, "Unknown intrinsic: ");
nir_print_instr(&instr->instr, stderr);
@@ -6757,6 +6752,9 @@ void ac_nir_translate(struct ac_llvm_context *ac, struct ac_shader_abi *abi,
struct ac_nir_context ctx = {};
struct nir_function *func;
/* Last minute passes for both radv & radeonsi */
ac_lower_subgroups(nir);
ctx.ac = *ac;
ctx.abi = abi;

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@@ -235,4 +235,6 @@ void ac_lower_indirect_derefs(struct nir_shader *nir, enum chip_class);
void ac_nir_translate(struct ac_llvm_context *ac, struct ac_shader_abi *abi,
struct nir_shader *nir);
bool ac_lower_subgroups(struct nir_shader *shader);
#endif /* AC_NIR_TO_LLVM_H */

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@@ -35,6 +35,7 @@ amd_common_files = files(
'ac_llvm_helper.cpp',
'ac_llvm_util.c',
'ac_llvm_util.h',
'ac_lower_subgroups.c',
'ac_shader_abi.h',
'ac_shader_info.c',
'ac_shader_info.h',