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[BOLT][NFC] Add hash computation for basic blocks
Extending yaml profile format with block hashes, which are used for stale profile matching. To avoid duplication of the code, created a new class with a collection of utilities for computing hashes. Reviewed By: Amir Differential Revision: https://reviews.llvm.org/D144306
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,41 @@ | ||
| //===- bolt/Core/HashUtilities.h - Misc hash utilities --------------------===// | ||
| // | ||
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. | ||
| // See https://llvm.org/LICENSE.txt for license information. | ||
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception | ||
| // | ||
| //===----------------------------------------------------------------------===// | ||
| // | ||
| // This file contains functions for computing hash values over BinaryFunction | ||
| // and BinaryBasicBlock. | ||
| // | ||
| //===----------------------------------------------------------------------===// | ||
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| #ifndef BOLT_CORE_HASH_UTILITIES_H | ||
| #define BOLT_CORE_HASH_UTILITIES_H | ||
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| #include "bolt/Core/BinaryBasicBlock.h" | ||
| #include "bolt/Core/BinaryContext.h" | ||
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| namespace llvm { | ||
| namespace bolt { | ||
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| uint16_t hash_64_to_16(const uint64_t Hash); | ||
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| std::string hashInteger(uint64_t Value); | ||
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| std::string hashSymbol(BinaryContext &BC, const MCSymbol &Symbol); | ||
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| std::string hashExpr(BinaryContext &BC, const MCExpr &Expr); | ||
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| std::string hashInstOperand(BinaryContext &BC, const MCOperand &Operand); | ||
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| using OperandHashFuncTy = function_ref<typename std::string(const MCOperand &)>; | ||
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| std::string hashBlock(BinaryContext &BC, const BinaryBasicBlock &BB, | ||
| OperandHashFuncTy OperandHashFunc); | ||
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| } // namespace bolt | ||
| } // namespace llvm | ||
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| #endif |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,135 @@ | ||
| //===- bolt/Core/HashUtilities.cpp - Misc hash utilities ------------------===// | ||
| // | ||
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. | ||
| // See https://llvm.org/LICENSE.txt for license information. | ||
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception | ||
| // | ||
| //===----------------------------------------------------------------------===// | ||
| // | ||
| // Computation of hash values over BinaryFunction and BinaryBasicBlock. | ||
| // | ||
| //===----------------------------------------------------------------------===// | ||
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| #include "bolt/Core/HashUtilities.h" | ||
| #include "bolt/Core/BinaryContext.h" | ||
| #include "bolt/Core/BinaryFunction.h" | ||
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| namespace llvm { | ||
| namespace bolt { | ||
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| /// Hashing a 64-bit integer to a 16-bit one. | ||
| uint16_t hash_64_to_16(const uint64_t Hash) { | ||
| uint16_t Res = (uint16_t)(Hash & 0xFFFF); | ||
| Res ^= (uint16_t)((Hash >> 16) & 0xFFFF); | ||
| Res ^= (uint16_t)((Hash >> 32) & 0xFFFF); | ||
| Res ^= (uint16_t)((Hash >> 48) & 0xFFFF); | ||
| return Res; | ||
| } | ||
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| std::string hashInteger(uint64_t Value) { | ||
| std::string HashString; | ||
| if (Value == 0) | ||
| HashString.push_back(0); | ||
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| while (Value) { | ||
| uint8_t LSB = Value & 0xff; | ||
| HashString.push_back(LSB); | ||
| Value >>= 8; | ||
| } | ||
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| return HashString; | ||
| } | ||
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| std::string hashSymbol(BinaryContext &BC, const MCSymbol &Symbol) { | ||
| std::string HashString; | ||
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| // Ignore function references. | ||
| if (BC.getFunctionForSymbol(&Symbol)) | ||
| return HashString; | ||
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| llvm::ErrorOr<uint64_t> ErrorOrValue = BC.getSymbolValue(Symbol); | ||
| if (!ErrorOrValue) | ||
| return HashString; | ||
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| // Ignore jump table references. | ||
| if (BC.getJumpTableContainingAddress(*ErrorOrValue)) | ||
| return HashString; | ||
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| return HashString.append(hashInteger(*ErrorOrValue)); | ||
| } | ||
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| std::string hashExpr(BinaryContext &BC, const MCExpr &Expr) { | ||
| switch (Expr.getKind()) { | ||
| case MCExpr::Constant: | ||
| return hashInteger(cast<MCConstantExpr>(Expr).getValue()); | ||
| case MCExpr::SymbolRef: | ||
| return hashSymbol(BC, cast<MCSymbolRefExpr>(Expr).getSymbol()); | ||
| case MCExpr::Unary: { | ||
| const auto &UnaryExpr = cast<MCUnaryExpr>(Expr); | ||
| return hashInteger(UnaryExpr.getOpcode()) | ||
| .append(hashExpr(BC, *UnaryExpr.getSubExpr())); | ||
| } | ||
| case MCExpr::Binary: { | ||
| const auto &BinaryExpr = cast<MCBinaryExpr>(Expr); | ||
| return hashExpr(BC, *BinaryExpr.getLHS()) | ||
| .append(hashInteger(BinaryExpr.getOpcode())) | ||
| .append(hashExpr(BC, *BinaryExpr.getRHS())); | ||
| } | ||
| case MCExpr::Target: | ||
| return std::string(); | ||
| } | ||
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| llvm_unreachable("invalid expression kind"); | ||
| } | ||
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| std::string hashInstOperand(BinaryContext &BC, const MCOperand &Operand) { | ||
| if (Operand.isImm()) | ||
| return hashInteger(Operand.getImm()); | ||
| if (Operand.isReg()) | ||
| return hashInteger(Operand.getReg()); | ||
| if (Operand.isExpr()) | ||
| return hashExpr(BC, *Operand.getExpr()); | ||
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| return std::string(); | ||
| } | ||
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| std::string hashBlock(BinaryContext &BC, const BinaryBasicBlock &BB, | ||
| OperandHashFuncTy OperandHashFunc) { | ||
| const bool IsX86 = BC.isX86(); | ||
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| // The hash is computed by creating a string of all instruction opcodes and | ||
| // possibly their operands and then hashing that string with std::hash. | ||
| std::string HashString; | ||
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| for (const MCInst &Inst : BB) { | ||
| if (BC.MIB->isPseudo(Inst)) | ||
| continue; | ||
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| unsigned Opcode = Inst.getOpcode(); | ||
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| // Ignore unconditional jumps since we check CFG consistency by processing | ||
| // basic blocks in order and do not rely on branches to be in-sync with | ||
| // CFG. Note that we still use condition code of conditional jumps. | ||
| if (BC.MIB->isUnconditionalBranch(Inst)) | ||
| continue; | ||
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| if (IsX86 && BC.MIB->isConditionalBranch(Inst)) | ||
| Opcode = BC.MIB->getShortBranchOpcode(Opcode); | ||
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| if (Opcode == 0) | ||
| HashString.push_back(0); | ||
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| while (Opcode) { | ||
| uint8_t LSB = Opcode & 0xff; | ||
| HashString.push_back(LSB); | ||
| Opcode = Opcode >> 8; | ||
| } | ||
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| for (const MCOperand &Op : MCPlus::primeOperands(Inst)) | ||
| HashString.append(OperandHashFunc(Op)); | ||
| } | ||
| return HashString; | ||
| } | ||
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| } // namespace bolt | ||
| } // namespace llvm |
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