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[DXBC] Fast mul path only for fully identical components because neg is post-abs

This commit is contained in:
Triang3l 2020-10-30 22:31:30 +03:00
parent feb8258a5e
commit ae3b68c7b6
2 changed files with 16 additions and 27 deletions
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15
src/xenia/gpu/dxbc_shader_translator_alu.cc
View File

@ -74,7 +74,7 @@ void DxbcShaderTranslator::ProcessVectorAluOperation(
DxbcOpMul(per_component_dest, operands[0], operands[1]);
uint32_t multiplicands_different =
used_result_components &
~instr.vector_operands[0].GetIdenticalMultiplicandComponents(
~instr.vector_operands[0].GetIdenticalComponents(
instr.vector_operands[1]);
if (multiplicands_different) {
// Shader Model 3: +-0 or denormal * anything = +0.
@ -181,15 +181,14 @@ void DxbcShaderTranslator::ProcessVectorAluOperation(
component_count = 4;
}
result_swizzle = DxbcSrc::kXXXX;
uint32_t multiplicands_different =
uint32_t((1 << component_count) - 1) &
~instr.vector_operands[0].GetIdenticalMultiplicandComponents(
instr.vector_operands[1]);
uint32_t different = uint32_t((1 << component_count) - 1) &
~instr.vector_operands[0].GetIdenticalComponents(
instr.vector_operands[1]);
for (uint32_t i = 0; i < component_count; ++i) {
DxbcOpMul(DxbcDest::R(system_temp_result_, i ? 0b0010 : 0b0001),
operands[0].SelectFromSwizzled(i),
operands[1].SelectFromSwizzled(i));
if ((multiplicands_different & (1 << i)) != 0) {
if ((different & (1 << i)) != 0) {
// Shader Model 3: +-0 or denormal * anything = +0 (also not replacing
// true `0 + term` with movc of the term because +0 + -0 should result
// in +0, not -0).
@ -569,7 +568,7 @@ void DxbcShaderTranslator::ProcessVectorAluOperation(
DxbcOpMul(DxbcDest::R(system_temp_result_, 0b0010),
operands[0].SelectFromSwizzled(1),
operands[1].SelectFromSwizzled(1));
if (!(instr.vector_operands[0].GetIdenticalMultiplicandComponents(
if (!(instr.vector_operands[0].GetIdenticalComponents(
instr.vector_operands[1]) &
0b0010)) {
// Shader Model 3: +-0 or denormal * anything = +0.
@ -987,7 +986,7 @@ void DxbcShaderTranslator::ProcessScalarAluOperation(
case AluScalarOpcode::kMulsc0:
case AluScalarOpcode::kMulsc1:
DxbcOpMul(ps_dest, operand_0_a, operand_1);
if (!(instr.scalar_operands[0].GetIdenticalMultiplicandComponents(
if (!(instr.scalar_operands[0].GetIdenticalComponents(
instr.scalar_operands[1]) &
0b0001)) {
// Shader Model 3: +-0 or denormal * anything = +0.

28
src/xenia/gpu/shader.h
View File

@ -212,19 +212,18 @@ struct InstructionOperand {
return false;
}
// Returns which components of two operands are identical, so that
// multiplication of them would result in pow2 with + sign, including in case
// they're zero (because -0 * |-0|, or -0 * +0, is -0), for providing a fast
// path in emulation of the Shader Model 3 +-0 * x = +0 multiplication
// behavior (disregarding component_count for simplicity of usage with
// GetComponent, treating the rightmost component as replicated).
uint32_t GetIdenticalMultiplicandComponents(
const InstructionOperand& other) const {
// Returns which components of two operands will always be bitwise equal
// (disregarding component_count for simplicity of usage with GetComponent,
// treating the rightmost component as replicated). This, strictly with all
// conditions, must be used when emulating Shader Model 3 +-0 * x = +0
// multiplication behavior with IEEE-compliant multiplication (because
// -0 * |-0|, or -0 * +0, is -0, while the result must be +0).
uint32_t GetIdenticalComponents(const InstructionOperand& other) const {
if (storage_source != other.storage_source ||
storage_index != other.storage_index ||
storage_addressing_mode != other.storage_addressing_mode ||
is_absolute_value != other.is_absolute_value ||
(!is_absolute_value && is_negated != other.is_negated)) {
is_negated != other.is_negated ||
is_absolute_value != other.is_absolute_value) {
return 0;
}
uint32_t identical_components = 0;
@ -234,15 +233,6 @@ struct InstructionOperand {
}
return identical_components;
}
// Returns which components of two operands will always be bitwise equal
// (disregarding component_count for simplicity of usage with GetComponent,
// treating the rightmost component as replicated).
uint32_t GetIdenticalComponents(const InstructionOperand& other) const {
if (is_negated != other.is_negated) {
return 0;
}
return GetIdenticalMultiplicandComponents(other);
}
};
struct ParsedExecInstruction {