| 1 | //===-- SnippetGenerator.h --------------------------------------*- C++ -*-===// |
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| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | /// |
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| 9 | /// \file |
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| 10 | /// Defines the abstract SnippetGenerator class for generating code that allows |
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| 11 | /// measuring a certain property of instructions (e.g. latency). |
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| 12 | /// |
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| 13 | //===----------------------------------------------------------------------===// |
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| 14 | |
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| 15 | #ifndef LLVM_TOOLS_LLVM_EXEGESIS_SNIPPETGENERATOR_H |
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| 16 | #define LLVM_TOOLS_LLVM_EXEGESIS_SNIPPETGENERATOR_H |
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| 17 | |
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| 18 | #include "Assembler.h" |
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| 19 | #include "BenchmarkCode.h" |
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| 20 | #include "CodeTemplate.h" |
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| 21 | #include "LlvmState.h" |
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| 22 | #include "MCInstrDescView.h" |
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| 23 | #include "RegisterAliasing.h" |
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| 24 | #include "llvm/ADT/CombinationGenerator.h" |
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| 25 | #include "llvm/MC/MCInst.h" |
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| 26 | #include "llvm/Support/Error.h" |
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| 27 | #include <cstdlib> |
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| 28 | #include <memory> |
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| 29 | #include <vector> |
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| 30 | |
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| 31 | namespace llvm { |
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| 32 | namespace exegesis { |
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| 33 | |
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| 34 | std::vector<CodeTemplate> getSingleton(CodeTemplate &&CT); |
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| 35 | |
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| 36 | // Generates code templates that has a self-dependency. |
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| 37 | Expected<std::vector<CodeTemplate>> |
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| 38 | generateSelfAliasingCodeTemplates(InstructionTemplate Variant, |
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| 39 | const BitVector &ForbiddenRegisters); |
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| 40 | |
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| 41 | // Generates code templates without assignment constraints. |
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| 42 | Expected<std::vector<CodeTemplate>> |
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| 43 | generateUnconstrainedCodeTemplates(const InstructionTemplate &Variant, |
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| 44 | StringRef Msg); |
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| 45 | |
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| 46 | // A class representing failures that happened during Benchmark, they are used |
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| 47 | // to report informations to the user. |
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| 48 | class SnippetGeneratorFailure : public StringError { |
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| 49 | public: |
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| 50 | SnippetGeneratorFailure(const Twine &S); |
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| 51 | }; |
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| 52 | |
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| 53 | // Common code for all benchmark modes. |
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| 54 | class SnippetGenerator { |
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| 55 | public: |
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| 56 | struct Options { |
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| 57 | unsigned MaxConfigsPerOpcode = 1; |
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| 58 | }; |
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| 59 | |
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| 60 | explicit SnippetGenerator(const LLVMState &State, const Options &Opts); |
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| 61 | |
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| 62 | virtual ~SnippetGenerator(); |
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| 63 | |
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| 64 | // Calls generateCodeTemplate and expands it into one or more BenchmarkCode. |
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| 65 | Error generateConfigurations(const InstructionTemplate &Variant, |
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| 66 | std::vector<BenchmarkCode> &Benchmarks, |
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| 67 | const BitVector &) const; |
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| 68 | |
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| 69 | // Given a snippet, computes which registers the setup code needs to define. |
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| 70 | std::vector<RegisterValue> computeRegisterInitialValues( |
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| 71 | const std::vector<InstructionTemplate> &Snippet) const; |
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| 72 | |
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| 73 | protected: |
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| 74 | const LLVMState &State; |
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| 75 | const Options Opts; |
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| 76 | |
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| 77 | private: |
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| 78 | // API to be implemented by subclasses. |
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| 79 | virtual Expected<std::vector<CodeTemplate>> |
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| 80 | generateCodeTemplates(InstructionTemplate Variant, |
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| 81 | const BitVector &ForbiddenRegisters) const = 0; |
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| 82 | }; |
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| 83 | |
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| 84 | // A global Random Number Generator to randomize configurations. |
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| 85 | // FIXME: Move random number generation into an object and make it seedable for |
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| 86 | // unit tests. |
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| 87 | std::mt19937 &randomGenerator(); |
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| 88 | |
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| 89 | // Picks a random unsigned integer from 0 to Max (inclusive). |
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| 90 | size_t randomIndex(size_t Max); |
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| 91 | |
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| 92 | // Picks a random bit among the bits set in Vector and returns its index. |
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| 93 | // Precondition: Vector must have at least one bit set. |
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| 94 | size_t randomBit(const BitVector &Vector); |
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| 95 | |
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| 96 | // Picks a first bit that is common to these two vectors. |
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| 97 | std::optional<int> getFirstCommonBit(const BitVector &A, const BitVector &B); |
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| 98 | |
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| 99 | // Picks a random configuration, then selects a random def and a random use from |
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| 100 | // it and finally set the selected values in the provided InstructionInstances. |
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| 101 | void setRandomAliasing(const AliasingConfigurations &AliasingConfigurations, |
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| 102 | InstructionTemplate &DefIB, InstructionTemplate &UseIB); |
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| 103 | |
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| 104 | // Assigns a Random Value to all Variables in IT that are still Invalid. |
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| 105 | // Do not use any of the registers in `ForbiddenRegs`. |
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| 106 | Error randomizeUnsetVariables(const LLVMState &State, |
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| 107 | const BitVector &ForbiddenRegs, |
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| 108 | InstructionTemplate &IT); |
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| 109 | |
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| 110 | // Sanity check generated instruction. |
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| 111 | Error validateGeneratedInstruction(const LLVMState &State, const MCInst &Inst); |
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| 112 | |
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| 113 | } // namespace exegesis |
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| 114 | } // namespace llvm |
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| 115 | |
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| 116 | #endif // LLVM_TOOLS_LLVM_EXEGESIS_SNIPPETGENERATOR_H |
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| 117 | |
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