#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetAsmBackend.h"
+
using namespace llvm;
namespace {
return 0;
}
+ /// Get a data fragment to write into, creating a new one if the current
+ /// fragment is not a data fragment.
+ MCDataFragment *getOrCreateDataFragment() const {
+ MCDataFragment *F = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
+ if (!F)
+ F = new MCDataFragment(CurSectionData);
+ return F;
+ }
+
public:
MCMachOStreamer(MCContext &Context, TargetAsmBackend &TAB,
raw_ostream &_OS, MCCodeEmitter *_Emitter)
CurSectionData(0) {}
~MCMachOStreamer() {}
+ MCAssembler &getAssembler() { return Assembler; }
+
const MCExpr *AddValueSymbols(const MCExpr *Value) {
switch (Value->getKind()) {
case MCExpr::Target: assert(0 && "Can't handle target exprs yet!");
void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
- // FIXME: We should also use offsets into Fill fragments.
- MCDataFragment *F = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
- if (!F)
- F = new MCDataFragment(CurSectionData);
-
+ // FIXME: This is wasteful, we don't necessarily need to create a data
+ // fragment. Instead, we should mark the symbol as pointing into the data
+ // fragment if it exists, otherwise we should just queue the label and set its
+ // fragment pointer when we emit the next fragment.
+ MCDataFragment *F = getOrCreateDataFragment();
MCSymbolData &SD = Assembler.getOrCreateSymbolData(*Symbol);
assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
SD.setFragment(F);
}
void MCMachOStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
- MCDataFragment *DF = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
- if (!DF)
- DF = new MCDataFragment(CurSectionData);
- DF->getContents().append(Data.begin(), Data.end());
+ getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
}
void MCMachOStreamer::EmitValue(const MCExpr *Value, unsigned Size,
unsigned AddrSpace) {
- MCDataFragment *DF = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
- if (!DF)
- DF = new MCDataFragment(CurSectionData);
+ MCDataFragment *DF = getOrCreateDataFragment();
// Avoid fixups when possible.
int64_t AbsValue;
unsigned MaxBytesToEmit) {
if (MaxBytesToEmit == 0)
MaxBytesToEmit = ByteAlignment;
- // FIXME the 0x90 is the default x86 1 byte nop opcode.
- new MCAlignFragment(ByteAlignment, 0x90, 1, MaxBytesToEmit,
+ new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
true /* EmitNops */, CurSectionData);
// Update the maximum alignment on the current section if necessary.
CurSectionData->setHasInstructions(true);
+ // FIXME-PERF: Common case is that we don't need to relax, encode directly
+ // onto the data fragments buffers.
+
SmallVector<MCFixup, 4> Fixups;
SmallString<256> Code;
raw_svector_ostream VecOS(Code);
Assembler.getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
VecOS.flush();
- // Add the fixups and data.
- MCDataFragment *DF = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
- if (!DF)
- DF = new MCDataFragment(CurSectionData);
+ // FIXME: Eliminate this copy.
+ SmallVector<MCAsmFixup, 4> AsmFixups;
for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
MCFixup &F = Fixups[i];
- DF->addFixup(MCAsmFixup(DF->getContents().size()+F.getOffset(),
- *F.getValue(), F.getKind()));
+ AsmFixups.push_back(MCAsmFixup(F.getOffset(), *F.getValue(),
+ F.getKind()));
+ }
+
+ // See if we might need to relax this instruction, if so it needs its own
+ // fragment.
+ //
+ // FIXME-PERF: Support target hook to do a fast path that avoids the encoder,
+ // when we can immediately tell that we will get something which might need
+ // relaxation (and compute its size).
+ //
+ // FIXME-PERF: We should also be smart about immediately relaxing instructions
+ // which we can already show will never possibly fit (we can also do a very
+ // good job of this before we do the first relaxation pass, because we have
+ // total knowledge about undefined symbols at that point). Even now, though,
+ // we can do a decent job, especially on Darwin where scattering means that we
+ // are going to often know that we can never fully resolve a fixup.
+ if (Assembler.getBackend().MayNeedRelaxation(Inst, AsmFixups)) {
+ MCInstFragment *IF = new MCInstFragment(Inst, CurSectionData);
+
+ // Add the fixups and data.
+ //
+ // FIXME: Revisit this design decision when relaxation is done, we may be
+ // able to get away with not storing any extra data in the MCInst.
+ IF->getCode() = Code;
+ IF->getFixups() = AsmFixups;
+
+ return;
+ }
+
+ // Add the fixups and data.
+ MCDataFragment *DF = getOrCreateDataFragment();
+ for (unsigned i = 0, e = AsmFixups.size(); i != e; ++i) {
+ AsmFixups[i].Offset += DF->getContents().size();
+ DF->addFixup(AsmFixups[i]);
}
DF->getContents().append(Code.begin(), Code.end());
}
}
MCStreamer *llvm::createMachOStreamer(MCContext &Context, TargetAsmBackend &TAB,
- raw_ostream &OS, MCCodeEmitter *CE) {
- return new MCMachOStreamer(Context, TAB, OS, CE);
+ raw_ostream &OS, MCCodeEmitter *CE,
+ bool RelaxAll) {
+ MCMachOStreamer *S = new MCMachOStreamer(Context, TAB, OS, CE);
+ if (RelaxAll)
+ S->getAssembler().setRelaxAll(true);
+ return S;
}