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//===--- LayoutOverrideSource.cpp --Override Record Layouts ---------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "clang/Frontend/LayoutOverrideSource.h"
#include "clang/AST/Decl.h"
#include "clang/Basic/CharInfo.h"
#include "llvm/Support/raw_ostream.h"
#include <fstream>
#include <string>
using namespace clang;
/// Parse a simple identifier.
static std::string parseName(StringRef S) {
if (S.empty() || !isAsciiIdentifierStart(S[0]))
return "";
unsigned Offset = 1;
while (Offset < S.size() && isAsciiIdentifierContinue(S[Offset]))
++Offset;
return S.substr(0, Offset).str();
}
LayoutOverrideSource::LayoutOverrideSource(StringRef Filename) {
std::ifstream Input(Filename.str().c_str());
if (!Input.is_open())
return;
// Parse the output of -fdump-record-layouts.
std::string CurrentType;
Layout CurrentLayout;
bool ExpectingType = false;
while (Input.good()) {
std::string Line;
getline(Input, Line);
StringRef LineStr(Line);
// Determine whether the following line will start a
if (LineStr.contains("*** Dumping AST Record Layout")) {
// Flush the last type/layout, if there is one.
if (!CurrentType.empty())
Layouts[CurrentType] = CurrentLayout;
CurrentLayout = Layout();
ExpectingType = true;
continue;
}
// If we're expecting a type, grab it.
if (ExpectingType) {
ExpectingType = false;
StringRef::size_type Pos;
if ((Pos = LineStr.find("struct ")) != StringRef::npos)
LineStr = LineStr.substr(Pos + strlen("struct "));
else if ((Pos = LineStr.find("class ")) != StringRef::npos)
LineStr = LineStr.substr(Pos + strlen("class "));
else if ((Pos = LineStr.find("union ")) != StringRef::npos)
LineStr = LineStr.substr(Pos + strlen("union "));
else
continue;
// Find the name of the type.
CurrentType = parseName(LineStr);
CurrentLayout = Layout();
continue;
}
// Check for the size of the type.
StringRef::size_type Pos = LineStr.find(" Size:");
if (Pos != StringRef::npos) {
// Skip past the " Size:" prefix.
LineStr = LineStr.substr(Pos + strlen(" Size:"));
unsigned long long Size = 0;
(void)LineStr.getAsInteger(10, Size);
CurrentLayout.Size = Size;
continue;
}
// Check for the alignment of the type.
Pos = LineStr.find("Alignment:");
if (Pos != StringRef::npos) {
// Skip past the "Alignment:" prefix.
LineStr = LineStr.substr(Pos + strlen("Alignment:"));
unsigned long long Alignment = 0;
(void)LineStr.getAsInteger(10, Alignment);
CurrentLayout.Align = Alignment;
continue;
}
// Check for the size/alignment of the type.
Pos = LineStr.find("sizeof=");
if (Pos != StringRef::npos) {
/* Skip past the sizeof= prefix. */
LineStr = LineStr.substr(Pos + strlen("sizeof="));
// Parse size.
unsigned long long Size = 0;
(void)LineStr.getAsInteger(10, Size);
CurrentLayout.Size = Size;
Pos = LineStr.find("align=");
if (Pos != StringRef::npos) {
/* Skip past the align= prefix. */
LineStr = LineStr.substr(Pos + strlen("align="));
// Parse alignment.
unsigned long long Alignment = 0;
(void)LineStr.getAsInteger(10, Alignment);
CurrentLayout.Align = Alignment;
}
continue;
}
// Check for the field offsets of the type.
Pos = LineStr.find("FieldOffsets: [");
if (Pos == StringRef::npos)
continue;
LineStr = LineStr.substr(Pos + strlen("FieldOffsets: ["));
while (!LineStr.empty() && isDigit(LineStr[0])) {
// Parse this offset.
unsigned Idx = 1;
while (Idx < LineStr.size() && isDigit(LineStr[Idx]))
++Idx;
unsigned long long Offset = 0;
(void)LineStr.substr(0, Idx).getAsInteger(10, Offset);
CurrentLayout.FieldOffsets.push_back(Offset);
// Skip over this offset, the following comma, and any spaces.
LineStr = LineStr.substr(Idx + 1);
while (!LineStr.empty() && isWhitespace(LineStr[0]))
LineStr = LineStr.substr(1);
}
}
// Flush the last type/layout, if there is one.
if (!CurrentType.empty())
Layouts[CurrentType] = CurrentLayout;
}
bool
LayoutOverrideSource::layoutRecordType(const RecordDecl *Record,
uint64_t &Size, uint64_t &Alignment,
llvm::DenseMap<const FieldDecl *, uint64_t> &FieldOffsets,
llvm::DenseMap<const CXXRecordDecl *, CharUnits> &BaseOffsets,
llvm::DenseMap<const CXXRecordDecl *, CharUnits> &VirtualBaseOffsets)
{
// We can't override unnamed declarations.
if (!Record->getIdentifier())
return false;
// Check whether we have a layout for this record.
llvm::StringMap<Layout>::iterator Known = Layouts.find(Record->getName());
if (Known == Layouts.end())
return false;
// Provide field layouts.
unsigned NumFields = 0;
for (RecordDecl::field_iterator F = Record->field_begin(),
FEnd = Record->field_end();
F != FEnd; ++F, ++NumFields) {
if (NumFields >= Known->second.FieldOffsets.size())
continue;
FieldOffsets[*F] = Known->second.FieldOffsets[NumFields];
}
// Wrong number of fields.
if (NumFields != Known->second.FieldOffsets.size())
return false;
Size = Known->second.Size;
Alignment = Known->second.Align;
return true;
}
LLVM_DUMP_METHOD void LayoutOverrideSource::dump() {
raw_ostream &OS = llvm::errs();
for (llvm::StringMap<Layout>::iterator L = Layouts.begin(),
LEnd = Layouts.end();
L != LEnd; ++L) {
OS << "Type: blah " << L->first() << '\n';
OS << " Size:" << L->second.Size << '\n';
OS << " Alignment:" << L->second.Align << '\n';
OS << " FieldOffsets: [";
for (unsigned I = 0, N = L->second.FieldOffsets.size(); I != N; ++I) {
if (I)
OS << ", ";
OS << L->second.FieldOffsets[I];
}
OS << "]\n";
}
}
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