void handleCalleeSaves(Code& code) { PhaseScope phaseScope(code, "handleCalleeSaves"); RegisterSet usedCalleeSaves; for (BasicBlock* block : code) { for (Inst& inst : *block) { inst.forEachTmpFast( [&] (Tmp& tmp) { // At first we just record all used regs. usedCalleeSaves.set(tmp.reg()); }); if (inst.hasSpecial()) usedCalleeSaves.merge(inst.extraClobberedRegs()); } } // Now we filter to really get the callee saves. usedCalleeSaves.filter(RegisterSet::calleeSaveRegisters()); usedCalleeSaves.exclude(RegisterSet::stackRegisters()); // We don't need to save FP here. if (!usedCalleeSaves.numberOfSetRegisters()) return; code.calleeSaveRegisters() = RegisterAtOffsetList(usedCalleeSaves); size_t byteSize = 0; for (const RegisterAtOffset& entry : code.calleeSaveRegisters()) byteSize = std::max(static_cast<size_t>(-entry.offset()), byteSize); StackSlot* savesArea = code.addStackSlot(byteSize, StackSlotKind::Locked); // This is a bit weird since we could have already pinned a different stack slot to this // area. Also, our runtime does not require us to pin the saves area. Maybe we shouldn't pin it? savesArea->setOffsetFromFP(-byteSize); auto argFor = [&] (const RegisterAtOffset& entry) -> Arg { return Arg::stack(savesArea, entry.offset() + byteSize); }; InsertionSet insertionSet(code); // First insert saving code in the prologue. for (const RegisterAtOffset& entry : code.calleeSaveRegisters()) { insertionSet.insert( 0, entry.reg().isGPR() ? Move : MoveDouble, code[0]->at(0).origin, Tmp(entry.reg()), argFor(entry)); } insertionSet.execute(code[0]); // Now insert restore code at epilogues. for (BasicBlock* block : code) { Inst& last = block->last(); if (!isReturn(last.opcode)) continue; for (const RegisterAtOffset& entry : code.calleeSaveRegisters()) { insertionSet.insert( block->size() - 1, entry.reg().isGPR() ? Move : MoveDouble, last.origin, argFor(entry), Tmp(entry.reg())); } insertionSet.execute(block); } }