172 lines
7.4 KiB
C++
172 lines
7.4 KiB
C++
// Copyright (c) 2017 Google Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef SOURCE_OPT_FOLD_H_
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#define SOURCE_OPT_FOLD_H_
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#include <cstdint>
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#include <vector>
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#include "source/opt/const_folding_rules.h"
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#include "source/opt/constants.h"
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#include "source/opt/def_use_manager.h"
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#include "source/opt/folding_rules.h"
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namespace spvtools {
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namespace opt {
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class InstructionFolder {
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public:
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explicit InstructionFolder(IRContext* context) : context_(context) {}
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// Returns the result of folding a scalar instruction with the given |opcode|
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// and |operands|. Each entry in |operands| is a pointer to an
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// analysis::Constant instance, which should've been created with the constant
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// manager (See IRContext::get_constant_mgr).
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//
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// It is an error to call this function with an opcode that does not pass the
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// IsFoldableOpcode test. If any error occurs during folding, the folder will
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// fail with a call to assert.
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uint32_t FoldScalars(
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SpvOp opcode,
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const std::vector<const analysis::Constant*>& operands) const;
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// Returns the result of performing an operation with the given |opcode| over
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// constant vectors with |num_dims| dimensions. Each entry in |operands| is a
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// pointer to an analysis::Constant instance, which should've been created
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// with the constant manager (See IRContext::get_constant_mgr).
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//
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// This function iterates through the given vector type constant operands and
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// calculates the result for each element of the result vector to return.
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// Vectors with longer than 32-bit scalar components are not accepted in this
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// function.
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//
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// It is an error to call this function with an opcode that does not pass the
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// IsFoldableOpcode test. If any error occurs during folding, the folder will
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// fail with a call to assert.
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std::vector<uint32_t> FoldVectors(
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SpvOp opcode, uint32_t num_dims,
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const std::vector<const analysis::Constant*>& operands) const;
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// Returns true if |opcode| represents an operation handled by FoldScalars or
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// FoldVectors.
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bool IsFoldableOpcode(SpvOp opcode) const;
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// Returns true if |cst| is supported by FoldScalars and FoldVectors.
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bool IsFoldableConstant(const analysis::Constant* cst) const;
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// Returns true if |FoldInstructionToConstant| could fold an instruction whose
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// result type is |type_inst|.
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bool IsFoldableType(Instruction* type_inst) const;
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// Tries to fold |inst| to a single constant, when the input ids to |inst|
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// have been substituted using |id_map|. Returns a pointer to the OpConstant*
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// instruction if successful. If necessary, a new constant instruction is
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// created and placed in the global values section.
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//
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// |id_map| is a function that takes one result id and returns another. It
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// can be used for things like CCP where it is known that some ids contain a
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// constant, but the instruction itself has not been updated yet. This can
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// map those ids to the appropriate constants.
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Instruction* FoldInstructionToConstant(
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Instruction* inst, std::function<uint32_t(uint32_t)> id_map) const;
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// Returns true if |inst| can be folded into a simpler instruction.
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// If |inst| can be simplified, |inst| is overwritten with the simplified
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// instruction reusing the same result id.
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//
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// If |inst| is simplified, it is possible that the resulting code in invalid
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// because the instruction is in a bad location. Callers of this function
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// have to handle the following cases:
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//
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// 1) An OpPhi becomes and OpCopyObject - If there are OpPhi instruction after
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// |inst| in a basic block then this is invalid. The caller must fix this
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// up.
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bool FoldInstruction(Instruction* inst) const;
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// Return true if this opcode has a const folding rule associtated with it.
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bool HasConstFoldingRule(SpvOp opcode) const {
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return GetConstantFoldingRules().HasFoldingRule(opcode);
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}
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private:
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// Returns a reference to the ConstnatFoldingRules instance.
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const ConstantFoldingRules& GetConstantFoldingRules() const {
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return const_folding_rules;
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}
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// Returns a reference to the FoldingRules instance.
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const FoldingRules& GetFoldingRules() const { return folding_rules; }
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// Returns the single-word result from performing the given unary operation on
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// the operand value which is passed in as a 32-bit word.
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uint32_t UnaryOperate(SpvOp opcode, uint32_t operand) const;
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// Returns the single-word result from performing the given binary operation
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// on the operand values which are passed in as two 32-bit word.
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uint32_t BinaryOperate(SpvOp opcode, uint32_t a, uint32_t b) const;
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// Returns the single-word result from performing the given ternary operation
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// on the operand values which are passed in as three 32-bit word.
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uint32_t TernaryOperate(SpvOp opcode, uint32_t a, uint32_t b,
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uint32_t c) const;
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// Returns the single-word result from performing the given operation on the
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// operand words. This only works with 32-bit operations and uses boolean
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// convention that 0u is false, and anything else is boolean true.
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// TODO(qining): Support operands other than 32-bit wide.
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uint32_t OperateWords(SpvOp opcode,
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const std::vector<uint32_t>& operand_words) const;
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bool FoldInstructionInternal(Instruction* inst) const;
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// Returns true if |inst| is a binary operation that takes two integers as
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// parameters and folds to a constant that can be represented as an unsigned
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// 32-bit value when the ids have been replaced by |id_map|. If |inst| can be
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// folded, the resulting value is returned in |*result|. Valid result types
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// for the instruction are any integer (signed or unsigned) with 32-bits or
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// less, or a boolean value.
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bool FoldBinaryIntegerOpToConstant(
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Instruction* inst, const std::function<uint32_t(uint32_t)>& id_map,
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uint32_t* result) const;
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// Returns true if |inst| is a binary operation on two boolean values, and
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// folds
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// to a constant boolean value when the ids have been replaced using |id_map|.
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// If |inst| can be folded, the result value is returned in |*result|.
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bool FoldBinaryBooleanOpToConstant(
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Instruction* inst, const std::function<uint32_t(uint32_t)>& id_map,
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uint32_t* result) const;
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// Returns true if |inst| can be folded to an constant when the ids have been
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// substituted using id_map. If it can, the value is returned in |result|. If
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// not, |result| is unchanged. It is assumed that not all operands are
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// constant. Those cases are handled by |FoldScalar|.
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bool FoldIntegerOpToConstant(Instruction* inst,
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const std::function<uint32_t(uint32_t)>& id_map,
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uint32_t* result) const;
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IRContext* context_;
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// Folding rules used by |FoldInstructionToConstant| and |FoldInstruction|.
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ConstantFoldingRules const_folding_rules;
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// Folding rules used by |FoldInstruction|.
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FoldingRules folding_rules;
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};
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} // namespace opt
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} // namespace spvtools
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#endif // SOURCE_OPT_FOLD_H_
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