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[WebAssembly] Cleanup WasmObjectWriter.cpp. NFC 

- Use auto where appropriate
- Use early return to reduce nesting
- Remove stray comment line
- Use C++ foreach over explicit iterator

Differential Revision: https://reviews.llvm.org/D34477

llvm-svn: 305971
This commit is contained in:
Sam Clegg 2017-06-21 23:46:41 +00:00
parent 3ed38c601a
commit fe6414b043
1 changed files with 62 additions and 70 deletions
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132
llvm/lib/MC/WasmObjectWriter.cpp
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@ -129,15 +129,15 @@ struct WasmGlobal {
// Information about a single relocation.
struct WasmRelocationEntry {
uint64_t Offset; // Where is the relocation.
const MCSymbolWasm *Symbol; // The symbol to relocate with.
int64_t Addend; // A value to add to the symbol.
unsigned Type; // The type of the relocation.
MCSectionWasm *FixupSection;// The section the relocation is targeting.
uint64_t Offset; // Where is the relocation.
const MCSymbolWasm *Symbol; // The symbol to relocate with.
int64_t Addend; // A value to add to the symbol.
unsigned Type; // The type of the relocation.
const MCSectionWasm *FixupSection;// The section the relocation is targeting.
WasmRelocationEntry(uint64_t Offset, const MCSymbolWasm *Symbol,
int64_t Addend, unsigned Type,
MCSectionWasm *FixupSection)
const MCSectionWasm *FixupSection)
: Offset(Offset), Symbol(Symbol), Addend(Addend), Type(Type),
FixupSection(FixupSection) {}
@ -350,7 +350,7 @@ void WasmObjectWriter::recordRelocation(MCAssembler &Asm,
const MCFragment *Fragment,
const MCFixup &Fixup, MCValue Target,
bool &IsPCRel, uint64_t &FixedValue) {
MCSectionWasm &FixupSection = cast<MCSectionWasm>(*Fragment->getParent());
const auto &FixupSection = cast<MCSectionWasm>(*Fragment->getParent());
uint64_t C = Target.getConstant();
uint64_t FixupOffset = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
MCContext &Ctx = Asm.getContext();
@ -477,8 +477,7 @@ static uint32_t ProvisionalValue(const WasmRelocationEntry &RelEntry) {
if (!Sym->isDefined(/*SetUsed=*/false))
return UINT32_MAX;
MCSectionWasm &Section =
cast<MCSectionWasm>(RelEntry.Symbol->getSection(false));
const auto &Section = cast<MCSectionWasm>(RelEntry.Symbol->getSection(false));
uint64_t Address = Section.getSectionOffset() + RelEntry.Addend;
// Ignore overflow. LLVM allows address arithmetic to silently wrap.
@ -766,8 +765,7 @@ void WasmObjectWriter::writeCodeSection(
encodeULEB128(Functions.size(), getStream());
for (const WasmFunction &Func : Functions) {
MCSectionWasm &FuncSection =
static_cast<MCSectionWasm &>(Func.Sym->getSection());
auto &FuncSection = static_cast<MCSectionWasm &>(Func.Sym->getSection());
int64_t Size = 0;
if (!Func.Sym->getSize()->evaluateAsAbsolute(Size, Layout))
@ -775,8 +773,7 @@ void WasmObjectWriter::writeCodeSection(
encodeULEB128(Size, getStream());
FuncSection.setSectionOffset(getStream().tell() -
Section.ContentsOffset);
FuncSection.setSectionOffset(getStream().tell() - Section.ContentsOffset);
Asm.writeSectionData(&FuncSection, Layout);
}
@ -1003,7 +1000,7 @@ void WasmObjectWriter::writeObject(MCAssembler &Asm,
const MCFragment &Frag = *GlobalVars->begin();
if (Frag.hasInstructions() || Frag.getKind() != MCFragment::FT_Data)
report_fatal_error("only data supported in .global_variables");
const MCDataFragment &DataFrag = cast<MCDataFragment>(Frag);
const auto &DataFrag = cast<MCDataFragment>(Frag);
if (!DataFrag.getFixups().empty())
report_fatal_error("fixups not supported in .global_variables");
const SmallVectorImpl<char> &Contents = DataFrag.getContents();
@ -1059,7 +1056,7 @@ void WasmObjectWriter::writeObject(MCAssembler &Asm,
const MCFragment &Frag = *StackPtr->begin();
if (Frag.hasInstructions() || Frag.getKind() != MCFragment::FT_Data)
report_fatal_error("only data supported in .stack_pointer");
const MCDataFragment &DataFrag = cast<MCDataFragment>(Frag);
const auto &DataFrag = cast<MCDataFragment>(Frag);
if (!DataFrag.getFixups().empty())
report_fatal_error("fixups not supported in .stack_pointer");
const SmallVectorImpl<char> &Contents = DataFrag.getContents();
@ -1093,8 +1090,6 @@ void WasmObjectWriter::writeObject(MCAssembler &Asm,
unsigned Index;
// << " function=" << S.isFunction()
if (WS.isFunction()) {
// Prepare the function's type, if we haven't seen it yet.
WasmFunctionType F;
@ -1142,68 +1137,65 @@ void WasmObjectWriter::writeObject(MCAssembler &Asm,
if (WS.isTemporary() && !WS.getSize())
continue;
if (WS.isDefined(/*SetUsed=*/false)) {
if (WS.getOffset() != 0)
report_fatal_error("data sections must contain one variable each: " +
WS.getName());
if (!WS.getSize())
report_fatal_error("data symbols must have a size set with .size: " +
WS.getName());
if (!WS.isDefined(/*SetUsed=*/false))
continue;
int64_t Size = 0;
if (!WS.getSize()->evaluateAsAbsolute(Size, Layout))
report_fatal_error(".size expression must be evaluatable");
if (WS.getOffset() != 0)
report_fatal_error("data sections must contain one variable each: " +
WS.getName());
if (!WS.getSize())
report_fatal_error("data symbols must have a size set with .size: " +
WS.getName());
MCSectionWasm &DataSection =
static_cast<MCSectionWasm &>(WS.getSection());
int64_t Size = 0;
if (!WS.getSize()->evaluateAsAbsolute(Size, Layout))
report_fatal_error(".size expression must be evaluatable");
if (uint64_t(Size) != Layout.getSectionFileSize(&DataSection))
report_fatal_error("data sections must contain at most one variable");
auto &DataSection = static_cast<MCSectionWasm &>(WS.getSection());
DataBytes.resize(alignTo(DataBytes.size(), DataSection.getAlignment()));
if (uint64_t(Size) != Layout.getSectionFileSize(&DataSection))
report_fatal_error("data sections must contain at most one variable");
DataSection.setSectionOffset(DataBytes.size());
DataBytes.resize(alignTo(DataBytes.size(), DataSection.getAlignment()));
for (MCSection::iterator I = DataSection.begin(), E = DataSection.end();
I != E; ++I) {
const MCFragment &Frag = *I;
if (Frag.hasInstructions())
report_fatal_error("only data supported in data sections");
DataSection.setSectionOffset(DataBytes.size());
if (const MCAlignFragment *Align = dyn_cast<MCAlignFragment>(&Frag)) {
if (Align->getValueSize() != 1)
report_fatal_error("only byte values supported for alignment");
// If nops are requested, use zeros, as this is the data section.
uint8_t Value = Align->hasEmitNops() ? 0 : Align->getValue();
uint64_t Size = std::min<uint64_t>(alignTo(DataBytes.size(),
Align->getAlignment()),
DataBytes.size() +
Align->getMaxBytesToEmit());
DataBytes.resize(Size, Value);
} else if (const MCFillFragment *Fill =
dyn_cast<MCFillFragment>(&Frag)) {
DataBytes.insert(DataBytes.end(), Size, Fill->getValue());
} else {
const MCDataFragment &DataFrag = cast<MCDataFragment>(Frag);
const SmallVectorImpl<char> &Contents = DataFrag.getContents();
for (const MCFragment &Frag : DataSection) {
if (Frag.hasInstructions())
report_fatal_error("only data supported in data sections");
DataBytes.insert(DataBytes.end(), Contents.begin(), Contents.end());
}
if (auto *Align = dyn_cast<MCAlignFragment>(&Frag)) {
if (Align->getValueSize() != 1)
report_fatal_error("only byte values supported for alignment");
// If nops are requested, use zeros, as this is the data section.
uint8_t Value = Align->hasEmitNops() ? 0 : Align->getValue();
uint64_t Size = std::min<uint64_t>(alignTo(DataBytes.size(),
Align->getAlignment()),
DataBytes.size() +
Align->getMaxBytesToEmit());
DataBytes.resize(Size, Value);
} else if (auto *Fill = dyn_cast<MCFillFragment>(&Frag)) {
DataBytes.insert(DataBytes.end(), Size, Fill->getValue());
} else {
const auto &DataFrag = cast<MCDataFragment>(Frag);
const SmallVectorImpl<char> &Contents = DataFrag.getContents();
DataBytes.insert(DataBytes.end(), Contents.begin(), Contents.end());
}
// For each global, prepare a corresponding wasm global holding its
// address. For externals these will also be named exports.
Index = NumGlobalImports + Globals.size();
WasmGlobal Global;
Global.Type = PtrType;
Global.IsMutable = false;
Global.HasImport = false;
Global.InitialValue = DataSection.getSectionOffset();
Global.ImportIndex = 0;
SymbolIndices[&WS] = Index;
Globals.push_back(Global);
}
// For each global, prepare a corresponding wasm global holding its
// address. For externals these will also be named exports.
Index = NumGlobalImports + Globals.size();
WasmGlobal Global;
Global.Type = PtrType;
Global.IsMutable = false;
Global.HasImport = false;
Global.InitialValue = DataSection.getSectionOffset();
Global.ImportIndex = 0;
SymbolIndices[&WS] = Index;
Globals.push_back(Global);
}
// If the symbol is visible outside this translation unit, export it.
@ -1231,7 +1223,7 @@ void WasmObjectWriter::writeObject(MCAssembler &Asm,
// Find the target symbol of this weak alias
const MCExpr *Expr = WS.getVariableValue();
auto *Inner = dyn_cast<MCSymbolRefExpr>(Expr);
const MCSymbolWasm *ResolvedSym = cast<MCSymbolWasm>(&Inner->getSymbol());
const auto *ResolvedSym = cast<MCSymbolWasm>(&Inner->getSymbol());
uint32_t Index = SymbolIndices.find(ResolvedSym)->second;
DEBUG(dbgs() << "Weak alias: '" << WS << "' -> '" << ResolvedSym << "' = " << Index << "\n");
SymbolIndices[&WS] = Index;