- MachineBasicBlock::iterator II, int SPAdj, unsigned FIOperandNum,
- RegScavenger *RS) const {
- llvm_unreachable("TODO: implement WebAssemblyRegisterInfo::eliminateFrameIndex");
+ MachineBasicBlock::iterator II, int SPAdj,
+ unsigned FIOperandNum, RegScavenger * /*RS*/) const {
+ assert(SPAdj == 0);
+ MachineInstr &MI = *II;
+
+ MachineBasicBlock &MBB = *MI.getParent();
+ MachineFunction &MF = *MBB.getParent();
+ int FrameIndex = MI.getOperand(FIOperandNum).getIndex();
+ const MachineFrameInfo& MFI = *MF.getFrameInfo();
+ int FrameOffset = MFI.getStackSize() + MFI.getObjectOffset(FrameIndex);
+
+ if (MI.mayLoadOrStore()) {
+ // If this is a load or store, make it relative to SP and fold the frame
+ // offset directly in
+ assert(MI.getOperand(1).getImm() == 0 &&
+ "Can't eliminate FI yet if offset is already set");
+ MI.getOperand(1).setImm(FrameOffset);
+ MI.getOperand(2).ChangeToRegister(WebAssembly::SP32, /*IsDef=*/false);
+ } else {
+ // Otherwise create an i32.add SP, offset and make it the operand
+ auto &MRI = MF.getRegInfo();
+ const auto *TII = MF.getSubtarget().getInstrInfo();
+
+ unsigned OffsetReg = MRI.createVirtualRegister(&WebAssembly::I32RegClass);
+ BuildMI(MBB, MI, MI.getDebugLoc(), TII->get(WebAssembly::CONST_I32), OffsetReg)
+ .addImm(FrameOffset);
+ BuildMI(MBB, MI, MI.getDebugLoc(), TII->get(WebAssembly::ADD_I32), OffsetReg)
+ .addReg(WebAssembly::SP32)
+ .addReg(OffsetReg);
+ MI.getOperand(FIOperandNum).ChangeToRegister(OffsetReg, /*IsDef=*/false);
+ }