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https://github.com/KhronosGroup/SPIRV-Tools
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1ebd860daa
The current folding routines have a very cumbersome interface, make them harder to use, and not a obvious how to extend. This change is to create a new interface for the folding routines, and show how it can be used by calling it from CCP. This does not make a significant change to the behaviour of CCP. In general it should produce the same code as before; however it is possible that an instruction that takes 32-bit integers as inputs and the result is not a 32-bit integer or bool will not be folded as before.
103 lines
4.4 KiB
C++
103 lines
4.4 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 LIBSPIRV_UTIL_FOLD_H_
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#define LIBSPIRV_UTIL_FOLD_H_
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#include "constants.h"
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#include "def_use_manager.h"
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#include <cstdint>
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#include <vector>
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namespace spvtools {
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namespace opt {
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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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// faill with a call to assert.
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uint32_t FoldScalars(SpvOp opcode,
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const std::vector<const analysis::Constant*>& operands);
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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 with
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// 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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// faill 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);
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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);
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// Returns true if |cst| is supported by FoldScalars and FoldVectors.
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bool IsFoldableConstant(const analysis::Constant* cst);
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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(ir::Instruction* type_inst);
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// Tries to fold |inst| to a single constant, when the input ids to |inst| have
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// 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 can
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// 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 map
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// those ids to the appropriate constants.
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ir::Instruction* FoldInstructionToConstant(
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ir::Instruction* inst, std::function<uint32_t(uint32_t)> id_map);
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// Tries to fold |inst| to a simpler instruction that computes the same value,
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// when the input ids to |inst| have been substituted using |id_map|. Returns a
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// pointer to the simplified instruction if successful. If necessary, a new
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// instruction is created and placed in the global values section, for
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// constants, or after |inst| for other instructions.
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//
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// |inst| must be an instruction that exists in the body of a function.
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//
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// |id_map| is a function that takes one result id and returns another. It can
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// 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 map
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// those ids to the appropriate constants.
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ir::Instruction* FoldInstruction(ir::Instruction* inst,
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std::function<uint32_t(uint32_t)> id_map);
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// The same as above when |id_map| is the identity function.
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inline ir::Instruction* FoldInstruction(ir::Instruction* inst) {
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auto identity_map = [](uint32_t id) { return id; };
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return FoldInstructionToConstant(inst, identity_map);
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}
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} // namespace opt
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} // namespace spvtools
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#endif // LIBSPIRV_UTIL_FOLD_H_
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