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gallium/radeon: reduce alloca of temporaries based on usagemask

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v2: take actual writemasks into account

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
This commit is contained in:
Nicolai Hähnle 2016-08-08 22:31:02 +02:00
parent 6bba956073
commit 8916d1e2fa
2 changed files with 54 additions and 10 deletions
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2
src/gallium/drivers/radeon/radeon_llvm.h
View file

@ -99,6 +99,8 @@ struct radeon_llvm_context {
struct tgsi_array_info *temp_arrays;
LLVMValueRef *temp_array_allocas;
LLVMValueRef undef_alloca;
LLVMValueRef main_fn;
LLVMTypeRef return_type;

62
src/gallium/drivers/radeon/radeon_setup_tgsi_llvm.c
View file

@ -185,6 +185,7 @@ get_pointer_into_array(struct radeon_llvm_context *ctx,
const struct tgsi_ind_register *reg_indirect)
{
unsigned array_id;
struct tgsi_array_info *array;
struct gallivm_state *gallivm = ctx->soa.bld_base.base.gallivm;
LLVMBuilderRef builder = gallivm->builder;
LLVMValueRef idxs[2];
@ -202,10 +203,23 @@ get_pointer_into_array(struct radeon_llvm_context *ctx,
if (!alloca)
return NULL;
array = &ctx->temp_arrays[array_id - 1];
if (!(array->writemask & (1 << swizzle)))
return ctx->undef_alloca;
index = emit_array_index(&ctx->soa, reg_indirect,
reg_index - ctx->temp_arrays[array_id - 1].range.First);
index = LLVMBuildMul(builder, index, lp_build_const_int32(gallivm, TGSI_NUM_CHANNELS), "");
index = LLVMBuildAdd(builder, index, lp_build_const_int32(gallivm, swizzle), "");
index = LLVMBuildMul(
builder, index,
lp_build_const_int32(gallivm, util_bitcount(array->writemask)),
"");
index = LLVMBuildAdd(
builder, index,
lp_build_const_int32(
gallivm,
util_bitcount(array->writemask & ((1 << swizzle) - 1))),
"");
idxs[0] = ctx->soa.bld_base.uint_bld.zero;
idxs[1] = index;
return LLVMBuildGEP(builder, alloca, idxs, 2, "");
@ -479,11 +493,18 @@ static void emit_declaration(struct lp_build_tgsi_context *bld_base,
char name[16] = "";
LLVMValueRef array_alloca = NULL;
unsigned decl_size;
unsigned writemask = decl->Declaration.UsageMask;
first = decl->Range.First;
last = decl->Range.Last;
decl_size = 4 * ((last - first) + 1);
if (decl->Declaration.Array) {
unsigned id = decl->Array.ArrayID - 1;
unsigned array_size;
writemask &= ctx->temp_arrays[id].writemask;
ctx->temp_arrays[id].writemask = writemask;
array_size = ((last - first) + 1) * util_bitcount(writemask);
/* If the array has more than 16 elements, store it
* in memory using an alloca that spans the entire
@ -491,7 +512,8 @@ static void emit_declaration(struct lp_build_tgsi_context *bld_base,
*
* Otherwise, store each array element individually.
* We will then generate vectors (per-channel, up to
* <4 x float>) for indirect addressing.
* <16 x float> if the usagemask is a single bit) for
* indirect addressing.
*
* Note that 16 is the number of vector elements that
* LLVM will store in a register, so theoretically an
@ -503,10 +525,10 @@ static void emit_declaration(struct lp_build_tgsi_context *bld_base,
* code path for arrays. LLVM should be smart enough to
* promote allocas into registers when profitable.
*/
if (decl_size > 16) {
if (array_size > 16) {
array_alloca = LLVMBuildAlloca(builder,
LLVMArrayType(bld_base->base.vec_type,
decl_size), "array");
array_size), "array");
ctx->temp_array_allocas[id] = array_alloca;
}
}
@ -531,14 +553,34 @@ static void emit_declaration(struct lp_build_tgsi_context *bld_base,
bld_base->uint_bld.zero,
NULL
};
unsigned j = 0;
if (writemask != TGSI_WRITEMASK_XYZW &&
!ctx->undef_alloca) {
/* Create a dummy alloca. We use it so that we
* have a pointer that is safe to load from if
* a shader ever reads from a channel that
* it never writes to.
*/
ctx->undef_alloca = si_build_alloca_undef(
bld_base->base.gallivm,
bld_base->base.vec_type, "undef");
}
for (i = 0; i < decl_size; ++i) {
LLVMValueRef ptr;
if (writemask & (1 << (i % 4))) {
#ifdef DEBUG
snprintf(name, sizeof(name), "TEMP%d.%c",
first + i / 4, "xyzw"[i % 4]);
snprintf(name, sizeof(name), "TEMP%d.%c",
first + i / 4, "xyzw"[i % 4]);
#endif
idxs[1] = lp_build_const_int32(bld_base->base.gallivm, i);
ctx->temps[first * TGSI_NUM_CHANNELS + i] =
LLVMBuildGEP(builder, array_alloca, idxs, 2, name);
idxs[1] = lp_build_const_int32(bld_base->base.gallivm, j);
ptr = LLVMBuildGEP(builder, array_alloca, idxs, 2, name);
j++;
} else {
ptr = ctx->undef_alloca;
}
ctx->temps[first * TGSI_NUM_CHANNELS + i] = ptr;
}
}
break;