Remove eliminateCallFramePseudoInstr and MIR comment

Author: JonPsson1

llvm/lib/Target/SystemZ/SystemZAsmPrinter.cpp

@@ -199,6 +199,10 @@ void SystemZAsmPrinter::emitInstruction(const MachineInstr *MI) {
   SystemZMCInstLower Lower(MF->getContext(), *this);
   MCInst LoweredMI;
   switch (MI->getOpcode()) {
+  case SystemZ::ADJCALLSTACKDOWN:
+  case SystemZ::ADJCALLSTACKUP:
+    return;
+
   case SystemZ::Return:
     LoweredMI = MCInstBuilder(SystemZ::BR)
       .addReg(SystemZ::R14D);

llvm/lib/Target/SystemZ/SystemZFrameLowering.cpp

@@ -66,22 +66,6 @@ SystemZFrameLowering::create(const SystemZSubtarget &STI) {
   return std::make_unique<SystemZELFFrameLowering>();
 }
 
-MachineBasicBlock::iterator SystemZFrameLowering::eliminateCallFramePseudoInstr(
-    MachineFunction &MF, MachineBasicBlock &MBB,
-    MachineBasicBlock::iterator MI) const {
-  switch (MI->getOpcode()) {
-  case SystemZ::ADJCALLSTACKDOWN:
-  case SystemZ::ADJCALLSTACKUP:
-    assert(hasReservedCallFrame(MF) &&
-           "ADJSTACKDOWN and ADJSTACKUP should be no-ops");
-    return MBB.erase(MI);
-    break;
-
-  default:
-    llvm_unreachable("Unexpected call frame instruction");
-  }
-}
-
 namespace {
 struct SZFrameSortingObj {
   bool IsValid = false;     // True if we care about this Object.

llvm/lib/Target/SystemZ/SystemZFrameLowering.h

@@ -41,9 +41,6 @@ class SystemZFrameLowering : public TargetFrameLowering {
   }
 
   bool hasReservedCallFrame(const MachineFunction &MF) const override;
-  MachineBasicBlock::iterator
-  eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
-                                MachineBasicBlock::iterator MI) const override;
 };
 
 class SystemZELFFrameLowering : public SystemZFrameLowering {

llvm/lib/Target/SystemZ/SystemZISelLowering.cpp

@@ -8108,15 +8108,17 @@ SystemZTargetLowering::emitAdjCallStack(MachineInstr &MI,
   // Do the work of MachineFrameInfo::computeMaxCallFrameSize() early and
   // remove these nodes. Given that these nodes start out as a glued sequence
   // it seems best to remove them here after instruction selection and
-  // scheduling.  NB: MIR testing does not work (yet) for call frames with
-  // this.
+  // scheduling.
   MachineFrameInfo &MFI = BB->getParent()->getFrameInfo();
   uint32_t NumBytes = MI.getOperand(0).getImm();
   if (NumBytes > MFI.getMaxCallFrameSize())
     MFI.setMaxCallFrameSize(NumBytes);
   MFI.setAdjustsStack(true);
 
-  MI.eraseFromParent();
+  // TODO: MI should be erased. For now, keep it around as it seems to help
+  // scheduling around calls slightly in general (fix MachineScheduler).
+  MI.getOperand(0).setImm(0);
+
   return BB;
 }
 

llvm/lib/Target/SystemZ/SystemZLongBranch.cpp

@@ -218,6 +218,8 @@ static unsigned getInstSizeInBytes(const MachineInstr &MI,
           // These do not have a size:
           MI.isDebugOrPseudoInstr() || MI.isPosition() || MI.isKill() ||
           MI.isImplicitDef() || MI.getOpcode() == TargetOpcode::MEMBARRIER ||
+          MI.getOpcode() == SystemZ::ADJCALLSTACKDOWN ||
+          MI.getOpcode() == SystemZ::ADJCALLSTACKUP ||
           // These have a size that may be zero:
           MI.isInlineAsm() || MI.getOpcode() == SystemZ::STACKMAP ||
           MI.getOpcode() == SystemZ::PATCHPOINT) &&