264 lines · cpp
1//===--- LayoutOverrideSource.cpp --Override Record Layouts ---------------===//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#include "clang/Frontend/LayoutOverrideSource.h"9#include "clang/AST/Decl.h"10#include "clang/AST/DeclCXX.h"11#include "clang/AST/Type.h"12#include "clang/Basic/CharInfo.h"13#include "llvm/Support/raw_ostream.h"14#include <fstream>15#include <string>16 17using namespace clang;18 19/// Parse a simple identifier.20static std::string parseName(StringRef S) {21 if (S.empty() || !isAsciiIdentifierStart(S[0]))22 return "";23 24 unsigned Offset = 1;25 while (Offset < S.size() && isAsciiIdentifierContinue(S[Offset]))26 ++Offset;27 28 return S.substr(0, Offset).str();29}30 31/// Parse an unsigned integer and move S to the next non-digit character.32static bool parseUnsigned(StringRef &S, unsigned long long &ULL) {33 if (S.empty() || !isDigit(S[0]))34 return false;35 unsigned Idx = 1;36 while (Idx < S.size() && isDigit(S[Idx]))37 ++Idx;38 (void)S.substr(0, Idx).getAsInteger(10, ULL);39 S = S.substr(Idx);40 return true;41}42 43LayoutOverrideSource::LayoutOverrideSource(StringRef Filename) {44 std::ifstream Input(Filename.str().c_str());45 if (!Input.is_open())46 return;47 48 // Parse the output of -fdump-record-layouts.49 std::string CurrentType;50 Layout CurrentLayout;51 bool ExpectingType = false;52 53 while (Input.good()) {54 std::string Line;55 getline(Input, Line);56 57 StringRef LineStr(Line);58 59 // Determine whether the following line will start a60 if (LineStr.contains("*** Dumping AST Record Layout")) {61 // Flush the last type/layout, if there is one.62 if (!CurrentType.empty())63 Layouts[CurrentType] = CurrentLayout;64 CurrentLayout = Layout();65 66 ExpectingType = true;67 continue;68 }69 70 // If we're expecting a type, grab it.71 if (ExpectingType) {72 ExpectingType = false;73 74 StringRef::size_type Pos;75 if ((Pos = LineStr.find("struct ")) != StringRef::npos)76 LineStr = LineStr.substr(Pos + strlen("struct "));77 else if ((Pos = LineStr.find("class ")) != StringRef::npos)78 LineStr = LineStr.substr(Pos + strlen("class "));79 else if ((Pos = LineStr.find("union ")) != StringRef::npos)80 LineStr = LineStr.substr(Pos + strlen("union "));81 else82 continue;83 84 // Find the name of the type.85 CurrentType = parseName(LineStr);86 CurrentLayout = Layout();87 continue;88 }89 90 // Check for the size of the type.91 StringRef::size_type Pos = LineStr.find(" Size:");92 if (Pos != StringRef::npos) {93 // Skip past the " Size:" prefix.94 LineStr = LineStr.substr(Pos + strlen(" Size:"));95 96 unsigned long long Size = 0;97 if (parseUnsigned(LineStr, Size))98 CurrentLayout.Size = Size;99 continue;100 }101 102 // Check for the alignment of the type.103 Pos = LineStr.find("Alignment:");104 if (Pos != StringRef::npos) {105 // Skip past the "Alignment:" prefix.106 LineStr = LineStr.substr(Pos + strlen("Alignment:"));107 108 unsigned long long Alignment = 0;109 if (parseUnsigned(LineStr, Alignment))110 CurrentLayout.Align = Alignment;111 continue;112 }113 114 // Check for the size/alignment of the type. The number follows "size=" or115 // "align=" indicates number of bytes.116 Pos = LineStr.find("sizeof=");117 if (Pos != StringRef::npos) {118 /* Skip past the sizeof= prefix. */119 LineStr = LineStr.substr(Pos + strlen("sizeof="));120 121 // Parse size.122 unsigned long long Size = 0;123 if (parseUnsigned(LineStr, Size))124 CurrentLayout.Size = Size * 8;125 126 Pos = LineStr.find("align=");127 if (Pos != StringRef::npos) {128 /* Skip past the align= prefix. */129 LineStr = LineStr.substr(Pos + strlen("align="));130 131 // Parse alignment.132 unsigned long long Alignment = 0;133 if (parseUnsigned(LineStr, Alignment))134 CurrentLayout.Align = Alignment * 8;135 }136 137 continue;138 }139 140 // Check for the field offsets of the type.141 Pos = LineStr.find("FieldOffsets: [");142 if (Pos != StringRef::npos) {143 LineStr = LineStr.substr(Pos + strlen("FieldOffsets: ["));144 while (!LineStr.empty() && isDigit(LineStr[0])) {145 unsigned long long Offset = 0;146 if (parseUnsigned(LineStr, Offset))147 CurrentLayout.FieldOffsets.push_back(Offset);148 149 // Skip over this offset, the following comma, and any spaces.150 LineStr = LineStr.substr(1);151 LineStr = LineStr.drop_while(isWhitespace);152 }153 }154 155 // Check for the virtual base offsets.156 Pos = LineStr.find("VBaseOffsets: [");157 if (Pos != StringRef::npos) {158 LineStr = LineStr.substr(Pos + strlen("VBaseOffsets: ["));159 while (!LineStr.empty() && isDigit(LineStr[0])) {160 unsigned long long Offset = 0;161 if (parseUnsigned(LineStr, Offset))162 CurrentLayout.VBaseOffsets.push_back(CharUnits::fromQuantity(Offset));163 164 // Skip over this offset, the following comma, and any spaces.165 LineStr = LineStr.substr(1);166 LineStr = LineStr.drop_while(isWhitespace);167 }168 continue;169 }170 171 // Check for the base offsets.172 Pos = LineStr.find("BaseOffsets: [");173 if (Pos != StringRef::npos) {174 LineStr = LineStr.substr(Pos + strlen("BaseOffsets: ["));175 while (!LineStr.empty() && isDigit(LineStr[0])) {176 unsigned long long Offset = 0;177 if (parseUnsigned(LineStr, Offset))178 CurrentLayout.BaseOffsets.push_back(CharUnits::fromQuantity(Offset));179 180 // Skip over this offset, the following comma, and any spaces.181 LineStr = LineStr.substr(1);182 LineStr = LineStr.drop_while(isWhitespace);183 }184 }185 }186 187 // Flush the last type/layout, if there is one.188 if (!CurrentType.empty())189 Layouts[CurrentType] = CurrentLayout;190}191 192bool193LayoutOverrideSource::layoutRecordType(const RecordDecl *Record,194 uint64_t &Size, uint64_t &Alignment,195 llvm::DenseMap<const FieldDecl *, uint64_t> &FieldOffsets,196 llvm::DenseMap<const CXXRecordDecl *, CharUnits> &BaseOffsets,197 llvm::DenseMap<const CXXRecordDecl *, CharUnits> &VirtualBaseOffsets)198{199 // We can't override unnamed declarations.200 if (!Record->getIdentifier())201 return false;202 203 // Check whether we have a layout for this record.204 llvm::StringMap<Layout>::iterator Known = Layouts.find(Record->getName());205 if (Known == Layouts.end())206 return false;207 208 // Provide field layouts.209 unsigned NumFields = 0;210 for (RecordDecl::field_iterator F = Record->field_begin(),211 FEnd = Record->field_end();212 F != FEnd; ++F, ++NumFields) {213 if (NumFields >= Known->second.FieldOffsets.size())214 continue;215 216 FieldOffsets[*F] = Known->second.FieldOffsets[NumFields];217 }218 219 // Wrong number of fields.220 if (NumFields != Known->second.FieldOffsets.size())221 return false;222 223 // Provide base offsets.224 if (const auto *RD = dyn_cast<CXXRecordDecl>(Record)) {225 unsigned NumNB = 0;226 unsigned NumVB = 0;227 for (const auto &I : RD->vbases()) {228 if (NumVB >= Known->second.VBaseOffsets.size())229 continue;230 const CXXRecordDecl *VBase = I.getType()->getAsCXXRecordDecl();231 VirtualBaseOffsets[VBase] = Known->second.VBaseOffsets[NumVB++];232 }233 for (const auto &I : RD->bases()) {234 if (I.isVirtual() || NumNB >= Known->second.BaseOffsets.size())235 continue;236 const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();237 BaseOffsets[Base] = Known->second.BaseOffsets[NumNB++];238 }239 }240 241 Size = Known->second.Size;242 Alignment = Known->second.Align;243 return true;244}245 246LLVM_DUMP_METHOD void LayoutOverrideSource::dump() {247 raw_ostream &OS = llvm::errs();248 for (llvm::StringMap<Layout>::iterator L = Layouts.begin(),249 LEnd = Layouts.end();250 L != LEnd; ++L) {251 OS << "Type: blah " << L->first() << '\n';252 OS << " Size:" << L->second.Size << '\n';253 OS << " Alignment:" << L->second.Align << '\n';254 OS << " FieldOffsets: [";255 for (unsigned I = 0, N = L->second.FieldOffsets.size(); I != N; ++I) {256 if (I)257 OS << ", ";258 OS << L->second.FieldOffsets[I];259 }260 OS << "]\n";261 }262}263 264