93 lines · cpp
1//===-- RISCVISAUtils.cpp - RISC-V ISA Utilities --------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8//9// Utilities shared by TableGen and RISCVISAInfo.10//11//===----------------------------------------------------------------------===//12 13#include "llvm/Support/RISCVISAUtils.h"14#include "llvm/ADT/StringExtras.h"15#include <cassert>16 17using namespace llvm;18 19// We rank extensions in the following order:20// -Single letter extensions in canonical order.21// -Unknown single letter extensions in alphabetical order.22// -Multi-letter extensions starting with 'z' sorted by canonical order of23// the second letter then sorted alphabetically.24// -Multi-letter extensions starting with 's' in alphabetical order.25// -(TODO) Multi-letter extensions starting with 'zxm' in alphabetical order.26// -X extensions in alphabetical order.27// -Unknown multi-letter extensions in alphabetical order.28// These flags are used to indicate the category. The first 6 bits store the29// single letter extension rank for single letter and multi-letter extensions30// starting with 'z'.31enum RankFlags {32 RF_Z_EXTENSION = 1 << 6,33 RF_S_EXTENSION = 2 << 6,34 RF_X_EXTENSION = 3 << 6,35 RF_UNKNOWN_MULTILETTER_EXTENSION = 4 << 6,36};37 38// Get the rank for single-letter extension, lower value meaning higher39// priority.40static unsigned singleLetterExtensionRank(char Ext) {41 assert(isLower(Ext));42 switch (Ext) {43 case 'i':44 return 0;45 case 'e':46 return 1;47 }48 49 size_t Pos = RISCVISAUtils::AllStdExts.find(Ext);50 if (Pos != StringRef::npos)51 return Pos + 2; // Skip 'e' and 'i' from above.52 53 // If we got an unknown extension letter, then give it an alphabetical54 // order, but after all known standard extensions.55 return 2 + RISCVISAUtils::AllStdExts.size() + (Ext - 'a');56}57 58// Get the rank for multi-letter extension, lower value meaning higher59// priority/order in canonical order.60static unsigned getExtensionRank(const std::string &ExtName) {61 assert(ExtName.size() >= 1);62 switch (ExtName[0]) {63 case 's':64 return RF_S_EXTENSION;65 case 'z':66 assert(ExtName.size() >= 2);67 // `z` extension must be sorted by canonical order of second letter.68 // e.g. zmx has higher rank than zax.69 return RF_Z_EXTENSION | singleLetterExtensionRank(ExtName[1]);70 case 'x':71 return RF_X_EXTENSION;72 default:73 if (ExtName.size() == 1)74 return singleLetterExtensionRank(ExtName[0]);75 return RF_UNKNOWN_MULTILETTER_EXTENSION;76 }77}78 79// Compare function for extension.80// Only compare the extension name, ignore version comparison.81bool llvm::RISCVISAUtils::compareExtension(const std::string &LHS,82 const std::string &RHS) {83 unsigned LHSRank = getExtensionRank(LHS);84 unsigned RHSRank = getExtensionRank(RHS);85 86 // If the ranks differ, pick the lower rank.87 if (LHSRank != RHSRank)88 return LHSRank < RHSRank;89 90 // If the rank is same, it must be sorted by lexicographic order.91 return LHS < RHS;92}93