[PATCH] D120161: [AArch64][GlobalISel] Constrain the right MOs when lowering calls.

[Ahmed Bougacha via Phabricator via llvm-commits]

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>From what I can tell, this was constraining the stale Info.Callee MO instead of the one we copied into the MI.

In addition, with c8b8c8e989e <https://reviews.llvm.org/rGc8b8c8e989e5aaf53494ea2f5021d238b6d77184>, when there's an attachedcall, the Callee is at position 1 rather than 0.

Found downstream with ptrauth, which has a full operand list in its description rather than variable_ops.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D120161

Files:
  llvm/lib/Target/AArch64/GISel/AArch64CallLowering.cpp


Index: llvm/lib/Target/AArch64/GISel/AArch64CallLowering.cpp
===================================================================
--- llvm/lib/Target/AArch64/GISel/AArch64CallLowering.cpp
+++ llvm/lib/Target/AArch64/GISel/AArch64CallLowering.cpp
@@ -1059,10 +1059,10 @@
 
   // If Callee is a reg, since it is used by a target specific instruction,
   // it must have a register class matching the constraint of that instruction.
-  if (Info.Callee.isReg())
+  if (MIB->getOperand(0).isReg())
     constrainOperandRegClass(MF, *TRI, MRI, *MF.getSubtarget().getInstrInfo(),
                              *MF.getSubtarget().getRegBankInfo(), *MIB,
-                             MIB->getDesc(), Info.Callee, 0);
+                             MIB->getDesc(), MIB->getOperand(0), 0);
 
   MF.getFrameInfo().setHasTailCall();
   Info.LoweredTailCall = true;
@@ -1139,12 +1139,16 @@
     Opc = getCallOpcode(MF, Info.Callee.isReg(), false);
 
   auto MIB = MIRBuilder.buildInstrNoInsert(Opc);
+  unsigned CalleeOpNo = 0;
+
   if (Opc == AArch64::BLR_RVMARKER) {
     // Add a target global address for the retainRV/claimRV runtime function
     // just before the call target.
     Function *ARCFn = *objcarc::getAttachedARCFunction(Info.CB);
     MIB.addGlobalAddress(ARCFn);
+    ++CalleeOpNo;
   }
+
   MIB.add(Info.Callee);
 
   // Tell the call which registers are clobbered.
@@ -1175,10 +1179,10 @@
   // If Callee is a reg, since it is used by a target specific
   // instruction, it must have a register class matching the
   // constraint of that instruction.
-  if (Info.Callee.isReg())
+  if (MIB->getOperand(CalleeOpNo).isReg())
     constrainOperandRegClass(MF, *TRI, MRI, *Subtarget.getInstrInfo(),
                              *Subtarget.getRegBankInfo(), *MIB, MIB->getDesc(),
-                             Info.Callee, 0);
+                             MIB->getOperand(CalleeOpNo), CalleeOpNo);
 
   // Finally we can copy the returned value back into its virtual-register. In
   // symmetry with the arguments, the physical register must be an


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