SPIRV-Tools/source/opt/fold.cpp
Diego Novillo 1acce99255 Fix https://github.com/KhronosGroup/SPIRV-Tools/issues/1130
This addresses review feedback for the CCP implementation (which fixes
https://github.com/KhronosGroup/SPIRV-Tools/issues/889).

This adds more protection around the folding of instructions that would
not be supported by the folder.
2017-12-22 13:33:17 -05:00

294 lines
10 KiB
C++

// Copyright (c) 2017 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "fold.h"
#include "def_use_manager.h"
#include <cassert>
#include <vector>
namespace spvtools {
namespace opt {
namespace {
// Returns the single-word result from performing the given unary operation on
// the operand value which is passed in as a 32-bit word.
uint32_t UnaryOperate(SpvOp opcode, uint32_t operand) {
switch (opcode) {
// Arthimetics
case SpvOp::SpvOpSNegate:
return -static_cast<int32_t>(operand);
case SpvOp::SpvOpNot:
return ~operand;
case SpvOp::SpvOpLogicalNot:
return !static_cast<bool>(operand);
default:
assert(false &&
"Unsupported unary operation for OpSpecConstantOp instruction");
return 0u;
}
}
// Returns the single-word result from performing the given binary operation on
// the operand values which are passed in as two 32-bit word.
uint32_t BinaryOperate(SpvOp opcode, uint32_t a, uint32_t b) {
switch (opcode) {
// Arthimetics
case SpvOp::SpvOpIAdd:
return a + b;
case SpvOp::SpvOpISub:
return a - b;
case SpvOp::SpvOpIMul:
return a * b;
case SpvOp::SpvOpUDiv:
assert(b != 0);
return a / b;
case SpvOp::SpvOpSDiv:
assert(b != 0u);
return (static_cast<int32_t>(a)) / (static_cast<int32_t>(b));
case SpvOp::SpvOpSRem: {
// The sign of non-zero result comes from the first operand: a. This is
// guaranteed by C++11 rules for integer division operator. The division
// result is rounded toward zero, so the result of '%' has the sign of
// the first operand.
assert(b != 0u);
return static_cast<int32_t>(a) % static_cast<int32_t>(b);
}
case SpvOp::SpvOpSMod: {
// The sign of non-zero result comes from the second operand: b
assert(b != 0u);
int32_t rem = BinaryOperate(SpvOp::SpvOpSRem, a, b);
int32_t b_prim = static_cast<int32_t>(b);
return (rem + b_prim) % b_prim;
}
case SpvOp::SpvOpUMod:
assert(b != 0u);
return (a % b);
// Shifting
case SpvOp::SpvOpShiftRightLogical: {
return a >> b;
}
case SpvOp::SpvOpShiftRightArithmetic:
return (static_cast<int32_t>(a)) >> b;
case SpvOp::SpvOpShiftLeftLogical:
return a << b;
// Bitwise operations
case SpvOp::SpvOpBitwiseOr:
return a | b;
case SpvOp::SpvOpBitwiseAnd:
return a & b;
case SpvOp::SpvOpBitwiseXor:
return a ^ b;
// Logical
case SpvOp::SpvOpLogicalEqual:
return (static_cast<bool>(a)) == (static_cast<bool>(b));
case SpvOp::SpvOpLogicalNotEqual:
return (static_cast<bool>(a)) != (static_cast<bool>(b));
case SpvOp::SpvOpLogicalOr:
return (static_cast<bool>(a)) || (static_cast<bool>(b));
case SpvOp::SpvOpLogicalAnd:
return (static_cast<bool>(a)) && (static_cast<bool>(b));
// Comparison
case SpvOp::SpvOpIEqual:
return a == b;
case SpvOp::SpvOpINotEqual:
return a != b;
case SpvOp::SpvOpULessThan:
return a < b;
case SpvOp::SpvOpSLessThan:
return (static_cast<int32_t>(a)) < (static_cast<int32_t>(b));
case SpvOp::SpvOpUGreaterThan:
return a > b;
case SpvOp::SpvOpSGreaterThan:
return (static_cast<int32_t>(a)) > (static_cast<int32_t>(b));
case SpvOp::SpvOpULessThanEqual:
return a <= b;
case SpvOp::SpvOpSLessThanEqual:
return (static_cast<int32_t>(a)) <= (static_cast<int32_t>(b));
case SpvOp::SpvOpUGreaterThanEqual:
return a >= b;
case SpvOp::SpvOpSGreaterThanEqual:
return (static_cast<int32_t>(a)) >= (static_cast<int32_t>(b));
default:
assert(false &&
"Unsupported binary operation for OpSpecConstantOp instruction");
return 0u;
}
}
// Returns the single-word result from performing the given ternary operation
// on the operand values which are passed in as three 32-bit word.
uint32_t TernaryOperate(SpvOp opcode, uint32_t a, uint32_t b, uint32_t c) {
switch (opcode) {
case SpvOp::SpvOpSelect:
return (static_cast<bool>(a)) ? b : c;
default:
assert(false &&
"Unsupported ternary operation for OpSpecConstantOp instruction");
return 0u;
}
}
// Returns the single-word result from performing the given operation on the
// operand words. This only works with 32-bit operations and uses boolean
// convention that 0u is false, and anything else is boolean true.
// TODO(qining): Support operands other than 32-bit wide.
uint32_t OperateWords(SpvOp opcode,
const std::vector<uint32_t>& operand_words) {
switch (operand_words.size()) {
case 1:
return UnaryOperate(opcode, operand_words.front());
case 2:
return BinaryOperate(opcode, operand_words.front(), operand_words.back());
case 3:
return TernaryOperate(opcode, operand_words[0], operand_words[1],
operand_words[2]);
default:
assert(false && "Invalid number of operands");
return 0;
}
}
} // namespace
// Returns the result of performing an operation on scalar constant operands.
// This function extracts the operand values as 32 bit words and returns the
// result in 32 bit word. Scalar constants with longer than 32-bit width are
// not accepted in this function.
uint32_t FoldScalars(SpvOp opcode,
const std::vector<const analysis::Constant*>& operands) {
assert(IsFoldableOpcode(opcode) &&
"Unhandled instruction opcode in FoldScalars");
std::vector<uint32_t> operand_values_in_raw_words;
for (const auto& operand : operands) {
if (const analysis::ScalarConstant* scalar = operand->AsScalarConstant()) {
const auto& scalar_words = scalar->words();
assert(scalar_words.size() == 1 &&
"Scalar constants with longer than 32-bit width are not allowed "
"in FoldScalars()");
operand_values_in_raw_words.push_back(scalar_words.front());
} else if (operand->AsNullConstant()) {
operand_values_in_raw_words.push_back(0u);
} else {
assert(false &&
"FoldScalars() only accepts ScalarConst or NullConst type of "
"constant");
}
}
return OperateWords(opcode, operand_values_in_raw_words);
}
std::vector<uint32_t> FoldVectors(
SpvOp opcode, uint32_t num_dims,
const std::vector<const analysis::Constant*>& operands) {
assert(IsFoldableOpcode(opcode) &&
"Unhandled instruction opcode in FoldVectors");
std::vector<uint32_t> result;
for (uint32_t d = 0; d < num_dims; d++) {
std::vector<uint32_t> operand_values_for_one_dimension;
for (const auto& operand : operands) {
if (const analysis::VectorConstant* vector_operand =
operand->AsVectorConstant()) {
// Extract the raw value of the scalar component constants
// in 32-bit words here. The reason of not using FoldScalars() here
// is that we do not create temporary null constants as components
// when the vector operand is a NullConstant because Constant creation
// may need extra checks for the validity and that is not manageed in
// here.
if (const analysis::ScalarConstant* scalar_component =
vector_operand->GetComponents().at(d)->AsScalarConstant()) {
const auto& scalar_words = scalar_component->words();
assert(
scalar_words.size() == 1 &&
"Vector components with longer than 32-bit width are not allowed "
"in FoldVectors()");
operand_values_for_one_dimension.push_back(scalar_words.front());
} else if (operand->AsNullConstant()) {
operand_values_for_one_dimension.push_back(0u);
} else {
assert(false &&
"VectorConst should only has ScalarConst or NullConst as "
"components");
}
} else if (operand->AsNullConstant()) {
operand_values_for_one_dimension.push_back(0u);
} else {
assert(false &&
"FoldVectors() only accepts VectorConst or NullConst type of "
"constant");
}
}
result.push_back(OperateWords(opcode, operand_values_for_one_dimension));
}
return result;
}
bool IsFoldableOpcode(SpvOp opcode) {
// NOTE: Extend to more opcodes as new cases are handled in the folder
// functions.
switch (opcode) {
case SpvOp::SpvOpBitwiseAnd:
case SpvOp::SpvOpBitwiseOr:
case SpvOp::SpvOpBitwiseXor:
case SpvOp::SpvOpIAdd:
case SpvOp::SpvOpIEqual:
case SpvOp::SpvOpIMul:
case SpvOp::SpvOpINotEqual:
case SpvOp::SpvOpISub:
case SpvOp::SpvOpLogicalAnd:
case SpvOp::SpvOpLogicalEqual:
case SpvOp::SpvOpLogicalNot:
case SpvOp::SpvOpLogicalNotEqual:
case SpvOp::SpvOpLogicalOr:
case SpvOp::SpvOpNot:
case SpvOp::SpvOpSDiv:
case SpvOp::SpvOpSelect:
case SpvOp::SpvOpSGreaterThan:
case SpvOp::SpvOpSGreaterThanEqual:
case SpvOp::SpvOpShiftLeftLogical:
case SpvOp::SpvOpShiftRightArithmetic:
case SpvOp::SpvOpShiftRightLogical:
case SpvOp::SpvOpSLessThan:
case SpvOp::SpvOpSLessThanEqual:
case SpvOp::SpvOpSMod:
case SpvOp::SpvOpSNegate:
case SpvOp::SpvOpSRem:
case SpvOp::SpvOpUDiv:
case SpvOp::SpvOpUGreaterThan:
case SpvOp::SpvOpUGreaterThanEqual:
case SpvOp::SpvOpULessThan:
case SpvOp::SpvOpULessThanEqual:
case SpvOp::SpvOpUMod:
return true;
default:
return false;
}
}
bool IsFoldableConstant(const analysis::Constant* cst) {
// Currently supported constants are 32-bit values or null constants.
if (const analysis::ScalarConstant* scalar = cst->AsScalarConstant())
return scalar->words().size() == 1;
else
return cst->AsNullConstant() != nullptr;
}
} // namespace opt
} // namespace spvtools