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-exception 6 // 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 17 using 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 of 23 // 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 the 29 // single letter extension rank for single letter and multi-letter extensions 30 // starting with 'z'. 31 enum 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 higher 39 // priority. 40 static 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 alphabetical 54 // 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 higher 59 // priority/order in canonical order. 60 static 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. 81 bool 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