void generate(Code& code, CCallHelpers& jit)
{
TimingScope timingScope("Air::generate");
// We don't expect the incoming code to have predecessors computed.
code.resetReachability();
if (shouldValidateIR())
validate(code);
// If we're doing super verbose dumping, the phase scope of any phase will already do a dump.
if (shouldDumpIR() && !shouldDumpIRAtEachPhase()) {
dataLog("Initial air:\n");
dataLog(code);
}
// This is where we run our optimizations and transformations.
// FIXME: Add Air optimizations.
// https://bugs.webkit.org/show_bug.cgi?id=150456
eliminateDeadCode(code);
// This is where we would have a real register allocator. Then, we could use spillEverything()
// in place of the register allocator only for testing.
// FIXME: https://bugs.webkit.org/show_bug.cgi?id=150457
spillEverything(code);
// Prior to this point the prologue and epilogue is implicit. This makes it explicit. It also
// does things like identify which callee-saves we're using and saves them.
handleCalleeSaves(code);
// This turns all Stack and CallArg Args into Addr args that use the frame pointer. It does
// this by first-fit allocating stack slots. It should be pretty darn close to optimal, so we
// shouldn't have to worry about this very much.
allocateStack(code);
// If we coalesced moves then we can unbreak critical edges. This is the main reason for this
// phase.
simplifyCFG(code);
// FIXME: We should really have a code layout optimization here.
// https://bugs.webkit.org/show_bug.cgi?id=150478
reportUsedRegisters(code);
if (shouldValidateIR())
validate(code);
// Do a final dump of Air. Note that we have to do this even if we are doing per-phase dumping,
// since the final generation is not a phase.
if (shouldDumpIR()) {
dataLog("Air after ", code.lastPhaseName(), ", before generation:\n");
dataLog(code);
}
TimingScope codeGenTimingScope("Air::generate backend");
// And now, we generate code.
jit.emitFunctionPrologue();
jit.addPtr(CCallHelpers::TrustedImm32(-code.frameSize()), MacroAssembler::stackPointerRegister);
GenerationContext context;
context.code = &code;
IndexMap<BasicBlock, CCallHelpers::Label> blockLabels(code.size());
IndexMap<BasicBlock, CCallHelpers::JumpList> blockJumps(code.size());
auto link = [&] (CCallHelpers::Jump jump, BasicBlock* target) {
if (blockLabels[target].isSet()) {
jump.linkTo(blockLabels[target], &jit);
return;
}
blockJumps[target].append(jump);
};
for (BasicBlock* block : code) {
blockJumps[block].link(&jit);
ASSERT(block->size() >= 1);
for (unsigned i = 0; i < block->size() - 1; ++i) {
CCallHelpers::Jump jump = block->at(i).generate(jit, context);
ASSERT_UNUSED(jump, !jump.isSet());
}
if (block->last().opcode == Jump
&& block->successorBlock(0) == code.findNextBlock(block))
continue;
if (block->last().opcode == Ret) {
// We currently don't represent the full prologue/epilogue in Air, so we need to
// have this override.
jit.emitFunctionEpilogue();
jit.ret();
continue;
}
CCallHelpers::Jump jump = block->last().generate(jit, context);
for (Inst& inst : *block)
jump = inst.generate(jit, context);
switch (block->numSuccessors()) {
case 0:
ASSERT(!jump.isSet());
break;
case 1:
link(jump, block->successorBlock(0));
break;
case 2:
link(jump, block->successorBlock(0));
if (block->successorBlock(1) != code.findNextBlock(block))
link(jit.jump(), block->successorBlock(1));
break;
default:
RELEASE_ASSERT_NOT_REACHED();
break;
}
}
for (auto& latePath : context.latePaths)
latePath->run(jit, context);
}
void generate(Code& code, CCallHelpers& jit)
{
TimingScope timingScope("Air::generate");
DisallowMacroScratchRegisterUsage disallowScratch(jit);
// And now, we generate code.
jit.emitFunctionPrologue();
if (code.frameSize())
jit.addPtr(CCallHelpers::TrustedImm32(-code.frameSize()), MacroAssembler::stackPointerRegister);
GenerationContext context;
context.code = &code;
IndexMap<BasicBlock, CCallHelpers::Label> blockLabels(code.size());
IndexMap<BasicBlock, CCallHelpers::JumpList> blockJumps(code.size());
auto link = [&] (CCallHelpers::Jump jump, BasicBlock* target) {
if (blockLabels[target].isSet()) {
jump.linkTo(blockLabels[target], &jit);
return;
}
blockJumps[target].append(jump);
};
for (BasicBlock* block : code) {
blockJumps[block].link(&jit);
blockLabels[block] = jit.label();
ASSERT(block->size() >= 1);
for (unsigned i = 0; i < block->size() - 1; ++i) {
CCallHelpers::Jump jump = block->at(i).generate(jit, context);
ASSERT_UNUSED(jump, !jump.isSet());
}
if (block->last().opcode == Jump
&& block->successorBlock(0) == code.findNextBlock(block))
continue;
if (block->last().opcode == Ret) {
// We currently don't represent the full prologue/epilogue in Air, so we need to
// have this override.
if (code.frameSize())
jit.emitFunctionEpilogue();
else
jit.emitFunctionEpilogueWithEmptyFrame();
jit.ret();
continue;
}
CCallHelpers::Jump jump = block->last().generate(jit, context);
switch (block->numSuccessors()) {
case 0:
ASSERT(!jump.isSet());
break;
case 1:
link(jump, block->successorBlock(0));
break;
case 2:
link(jump, block->successorBlock(0));
if (block->successorBlock(1) != code.findNextBlock(block))
link(jit.jump(), block->successorBlock(1));
break;
default:
RELEASE_ASSERT_NOT_REACHED();
break;
}
}
for (auto& latePath : context.latePaths)
latePath->run(jit, context);
}
