/// Measure each basic block, fill the BlockOffsets, and return the size of
/// the function, starting with BB
unsigned MSP430BSel::measureFunction(OffsetVector &BlockOffsets,
MachineBasicBlock *FromBB) {
// Give the blocks of the function a dense, in-order, numbering.
MF->RenumberBlocks(FromBB);
MachineFunction::iterator Begin;
if (FromBB == nullptr) {
Begin = MF->begin();
} else {
Begin = FromBB->getIterator();
}
BlockOffsets.resize(MF->getNumBlockIDs());
unsigned TotalSize = BlockOffsets[Begin->getNumber()];
for (auto &MBB : make_range(Begin, MF->end())) {
BlockOffsets[MBB.getNumber()] = TotalSize;
for (MachineInstr &MI : MBB) {
TotalSize += TII->getInstSizeInBytes(MI);
}
}
return TotalSize;
}
bool
ModuleGenerator::finishCodegen()
{
uint32_t offsetInWhole = masm_.size();
uint32_t numFuncExports = metadata_->funcExports.length();
MOZ_ASSERT(numFuncExports == exportedFuncs_.count());
// Generate stubs in a separate MacroAssembler since, otherwise, for modules
// larger than the JumpImmediateRange, even local uses of Label will fail
// due to the large absolute offsets temporarily stored by Label::bind().
OffsetVector entries;
ProfilingOffsetVector interpExits;
ProfilingOffsetVector jitExits;
EnumeratedArray<JumpTarget, JumpTarget::Limit, Offsets> jumpTargets;
Offsets interruptExit;
{
TempAllocator alloc(&lifo_);
MacroAssembler masm(MacroAssembler::AsmJSToken(), alloc);
if (!entries.resize(numFuncExports))
return false;
for (uint32_t i = 0; i < numFuncExports; i++)
entries[i] = GenerateEntry(masm, metadata_->funcExports[i]);
if (!interpExits.resize(numFuncImports()))
return false;
if (!jitExits.resize(numFuncImports()))
return false;
for (uint32_t i = 0; i < numFuncImports(); i++) {
interpExits[i] = GenerateInterpExit(masm, metadata_->funcImports[i], i);
jitExits[i] = GenerateJitExit(masm, metadata_->funcImports[i]);
}
for (JumpTarget target : MakeEnumeratedRange(JumpTarget::Limit))
jumpTargets[target] = GenerateJumpTarget(masm, target);
interruptExit = GenerateInterruptStub(masm);
if (masm.oom() || !masm_.asmMergeWith(masm))
return false;
}
// Adjust each of the resulting Offsets (to account for being merged into
// masm_) and then create code ranges for all the stubs.
for (uint32_t i = 0; i < numFuncExports; i++) {
entries[i].offsetBy(offsetInWhole);
metadata_->funcExports[i].initEntryOffset(entries[i].begin);
if (!metadata_->codeRanges.emplaceBack(CodeRange::Entry, entries[i]))
return false;
}
for (uint32_t i = 0; i < numFuncImports(); i++) {
interpExits[i].offsetBy(offsetInWhole);
metadata_->funcImports[i].initInterpExitOffset(interpExits[i].begin);
if (!metadata_->codeRanges.emplaceBack(CodeRange::ImportInterpExit, interpExits[i]))
return false;
jitExits[i].offsetBy(offsetInWhole);
metadata_->funcImports[i].initJitExitOffset(jitExits[i].begin);
if (!metadata_->codeRanges.emplaceBack(CodeRange::ImportJitExit, jitExits[i]))
return false;
}
for (JumpTarget target : MakeEnumeratedRange(JumpTarget::Limit)) {
jumpTargets[target].offsetBy(offsetInWhole);
if (!metadata_->codeRanges.emplaceBack(CodeRange::Inline, jumpTargets[target]))
return false;
}
interruptExit.offsetBy(offsetInWhole);
if (!metadata_->codeRanges.emplaceBack(CodeRange::Inline, interruptExit))
return false;
// Fill in LinkData with the offsets of these stubs.
linkData_.interruptOffset = interruptExit.begin;
linkData_.outOfBoundsOffset = jumpTargets[JumpTarget::OutOfBounds].begin;
linkData_.unalignedAccessOffset = jumpTargets[JumpTarget::UnalignedAccess].begin;
linkData_.badIndirectCallOffset = jumpTargets[JumpTarget::BadIndirectCall].begin;
// Only call convertOutOfRangeBranchesToThunks after all other codegen that may
// emit new jumps to JumpTargets has finished.
if (!convertOutOfRangeBranchesToThunks())
return false;
// Now that all thunks have been generated, patch all the thunks.
for (CallThunk& callThunk : metadata_->callThunks) {
uint32_t funcIndex = callThunk.u.funcIndex;
callThunk.u.codeRangeIndex = funcIndexToCodeRange_[funcIndex];
masm_.patchThunk(callThunk.offset, funcCodeRange(funcIndex).funcNonProfilingEntry());
}
for (JumpTarget target : MakeEnumeratedRange(JumpTarget::Limit)) {
for (uint32_t thunkOffset : jumpThunks_[target])
masm_.patchThunk(thunkOffset, jumpTargets[target].begin);
}
// Code-generation is complete!
masm_.finish();
return !masm_.oom();
}
/// Do expand branches and split the basic blocks if necessary.
/// Returns true if made any change.
bool MSP430BSel::expandBranches(OffsetVector &BlockOffsets) {
// For each conditional branch, if the offset to its destination is larger
// than the offset field allows, transform it into a long branch sequence
// like this:
// short branch:
// bCC MBB
// long branch:
// b!CC $PC+6
// b MBB
//
bool MadeChange = false;
for (auto MBB = MF->begin(), E = MF->end(); MBB != E; ++MBB) {
unsigned MBBStartOffset = 0;
for (auto MI = MBB->begin(), EE = MBB->end(); MI != EE; ++MI) {
MBBStartOffset += TII->getInstSizeInBytes(*MI);
// If this instruction is not a short branch then skip it.
if (MI->getOpcode() != MSP430::JCC && MI->getOpcode() != MSP430::JMP) {
continue;
}
MachineBasicBlock *DestBB = MI->getOperand(0).getMBB();
// Determine the distance from the current branch to the destination
// block. MBBStartOffset already includes the size of the current branch
// instruction.
int BlockDistance =
BlockOffsets[DestBB->getNumber()] - BlockOffsets[MBB->getNumber()];
int BranchDistance = BlockDistance - MBBStartOffset;
// If this branch is in range, ignore it.
if (isInRage(BranchDistance)) {
continue;
}
DEBUG(dbgs() << " Found a branch that needs expanding, BB#"
<< DestBB->getNumber() << ", Distance " << BranchDistance
<< "\n");
// If JCC is not the last instruction we need to split the MBB.
if (MI->getOpcode() == MSP430::JCC && std::next(MI) != EE) {
DEBUG(dbgs() << " Found a basic block that needs to be split, BB#"
<< MBB->getNumber() << "\n");
// Create a new basic block.
MachineBasicBlock *NewBB =
MF->CreateMachineBasicBlock(MBB->getBasicBlock());
MF->insert(std::next(MBB), NewBB);
// Splice the instructions following MI over to the NewBB.
NewBB->splice(NewBB->end(), &*MBB, std::next(MI), MBB->end());
// Update the successor lists.
for (MachineBasicBlock *Succ : MBB->successors()) {
if (Succ == DestBB) {
continue;
}
MBB->replaceSuccessor(Succ, NewBB);
NewBB->addSuccessor(Succ);
}
// We introduced a new MBB so all following blocks should be numbered
// and measured again.
measureFunction(BlockOffsets, &*MBB);
++NumSplit;
// It may be not necessary to start all over at this point, but it's
// safer do this anyway.
return true;
}
MachineInstr &OldBranch = *MI;
DebugLoc dl = OldBranch.getDebugLoc();
int InstrSizeDiff = -TII->getInstSizeInBytes(OldBranch);
if (MI->getOpcode() == MSP430::JCC) {
MachineBasicBlock *NextMBB = &*std::next(MBB);
assert(MBB->isSuccessor(NextMBB) &&
"This block must have a layout successor!");
// The BCC operands are:
// 0. Target MBB
// 1. MSP430 branch predicate
SmallVector<MachineOperand, 1> Cond;
Cond.push_back(MI->getOperand(1));
// Jump over the long branch on the opposite condition
TII->reverseBranchCondition(Cond);
MI = BuildMI(*MBB, MI, dl, TII->get(MSP430::JCC))
.addMBB(NextMBB)
.add(Cond[0]);
InstrSizeDiff += TII->getInstSizeInBytes(*MI);
++MI;
}
// Unconditional branch to the real destination.
MI = BuildMI(*MBB, MI, dl, TII->get(MSP430::Bi)).addMBB(DestBB);
InstrSizeDiff += TII->getInstSizeInBytes(*MI);
// Remove the old branch from the function.
OldBranch.eraseFromParent();
// The size of a new instruction is different from the old one, so we need
// to correct all block offsets.
for (int i = MBB->getNumber() + 1, e = BlockOffsets.size(); i < e; ++i) {
BlockOffsets[i] += InstrSizeDiff;
}
MBBStartOffset += InstrSizeDiff;
++NumExpanded;
MadeChange = true;
}
}
return MadeChange;
}
bool
ModuleGenerator::finishCodegen()
{
masm_.haltingAlign(CodeAlignment);
uint32_t offsetInWhole = masm_.size();
uint32_t numFuncExports = metadata_->funcExports.length();
MOZ_ASSERT(numFuncExports == exportedFuncs_.count());
// Generate stubs in a separate MacroAssembler since, otherwise, for modules
// larger than the JumpImmediateRange, even local uses of Label will fail
// due to the large absolute offsets temporarily stored by Label::bind().
OffsetVector entries;
ProfilingOffsetVector interpExits;
ProfilingOffsetVector jitExits;
TrapExitOffsetArray trapExits;
Offsets outOfBoundsExit;
Offsets unalignedAccessExit;
Offsets interruptExit;
Offsets throwStub;
{
TempAllocator alloc(&lifo_);
MacroAssembler masm(MacroAssembler::WasmToken(), alloc);
Label throwLabel;
if (!entries.resize(numFuncExports))
return false;
for (uint32_t i = 0; i < numFuncExports; i++)
entries[i] = GenerateEntry(masm, metadata_->funcExports[i]);
if (!interpExits.resize(numFuncImports()))
return false;
if (!jitExits.resize(numFuncImports()))
return false;
for (uint32_t i = 0; i < numFuncImports(); i++) {
interpExits[i] = GenerateImportInterpExit(masm, metadata_->funcImports[i], i, &throwLabel);
jitExits[i] = GenerateImportJitExit(masm, metadata_->funcImports[i], &throwLabel);
}
for (Trap trap : MakeEnumeratedRange(Trap::Limit))
trapExits[trap] = GenerateTrapExit(masm, trap, &throwLabel);
outOfBoundsExit = GenerateOutOfBoundsExit(masm, &throwLabel);
unalignedAccessExit = GenerateUnalignedExit(masm, &throwLabel);
interruptExit = GenerateInterruptExit(masm, &throwLabel);
throwStub = GenerateThrowStub(masm, &throwLabel);
if (masm.oom() || !masm_.asmMergeWith(masm))
return false;
}
// Adjust each of the resulting Offsets (to account for being merged into
// masm_) and then create code ranges for all the stubs.
for (uint32_t i = 0; i < numFuncExports; i++) {
entries[i].offsetBy(offsetInWhole);
metadata_->funcExports[i].initEntryOffset(entries[i].begin);
if (!metadata_->codeRanges.emplaceBack(CodeRange::Entry, entries[i]))
return false;
}
for (uint32_t i = 0; i < numFuncImports(); i++) {
interpExits[i].offsetBy(offsetInWhole);
metadata_->funcImports[i].initInterpExitOffset(interpExits[i].begin);
if (!metadata_->codeRanges.emplaceBack(CodeRange::ImportInterpExit, interpExits[i]))
return false;
jitExits[i].offsetBy(offsetInWhole);
metadata_->funcImports[i].initJitExitOffset(jitExits[i].begin);
if (!metadata_->codeRanges.emplaceBack(CodeRange::ImportJitExit, jitExits[i]))
return false;
}
for (Trap trap : MakeEnumeratedRange(Trap::Limit)) {
trapExits[trap].offsetBy(offsetInWhole);
if (!metadata_->codeRanges.emplaceBack(CodeRange::TrapExit, trapExits[trap]))
return false;
}
outOfBoundsExit.offsetBy(offsetInWhole);
if (!metadata_->codeRanges.emplaceBack(CodeRange::Inline, outOfBoundsExit))
return false;
unalignedAccessExit.offsetBy(offsetInWhole);
if (!metadata_->codeRanges.emplaceBack(CodeRange::Inline, unalignedAccessExit))
return false;
interruptExit.offsetBy(offsetInWhole);
if (!metadata_->codeRanges.emplaceBack(CodeRange::Inline, interruptExit))
return false;
throwStub.offsetBy(offsetInWhole);
if (!metadata_->codeRanges.emplaceBack(CodeRange::Inline, throwStub))
return false;
// Fill in LinkData with the offsets of these stubs.
linkData_.outOfBoundsOffset = outOfBoundsExit.begin;
linkData_.interruptOffset = interruptExit.begin;
// Now that all other code has been emitted, patch all remaining callsites.
if (!patchCallSites(&trapExits))
return false;
// Now that all code has been generated, patch far jumps to destinations.
for (CallThunk& callThunk : metadata_->callThunks) {
uint32_t funcIndex = callThunk.u.funcIndex;
callThunk.u.codeRangeIndex = funcToCodeRange_[funcIndex];
CodeOffset farJump(callThunk.offset);
masm_.patchFarJump(farJump, funcCodeRange(funcIndex).funcNonProfilingEntry());
}
for (const TrapFarJump& farJump : masm_.trapFarJumps())
masm_.patchFarJump(farJump.jump, trapExits[farJump.trap].begin);
// Code-generation is complete!
masm_.finish();
return !masm_.oom();
}