GlobalISel: support swifterror attribute on AArch64.

swifterror marks an argument as a register pretending to be a pointer, so we
need a guaranteed mem2reg-like analysis of its uses. Fortunately most of the
infrastructure can be reused from the DAG world.

llvm-svn: 361608

1 files changed, 14 insertions, 2 deletions

diff --git a/llvm/lib/Target/AArch64/AArch64CallLowering.cpp b/llvm/lib/Target/AArch64/AArch64CallLowering.cpp
index c568cd9b7c3..9d04dd86583 100644
--- a/llvm/lib/Target/AArch64/AArch64CallLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64CallLowering.cpp
@@ -232,7 +232,8 @@ void AArch64CallLowering::splitToValueTypes(
 
 bool AArch64CallLowering::lowerReturn(MachineIRBuilder &MIRBuilder,
                                       const Value *Val,
-                                      ArrayRef<unsigned> VRegs) const {
+                                      ArrayRef<unsigned> VRegs,
+                                      unsigned SwiftErrorVReg) const {
   auto MIB = MIRBuilder.buildInstrNoInsert(AArch64::RET_ReallyLR);
   assert(((Val && !VRegs.empty()) || (!Val && VRegs.empty())) &&
          "Return value without a vreg");
@@ -340,6 +341,11 @@ bool AArch64CallLowering::lowerReturn(MachineIRBuilder &MIRBuilder,
     Success = handleAssignments(MIRBuilder, SplitArgs, Handler);
   }
 
+  if (SwiftErrorVReg) {
+    MIB.addUse(AArch64::X21, RegState::Implicit);
+    MIRBuilder.buildCopy(AArch64::X21, SwiftErrorVReg);
+  }
+
   MIRBuilder.insertInstr(MIB);
   return Success;
 }
@@ -420,7 +426,8 @@ bool AArch64CallLowering::lowerCall(MachineIRBuilder &MIRBuilder,
                                     CallingConv::ID CallConv,
                                     const MachineOperand &Callee,
                                     const ArgInfo &OrigRet,
-                                    ArrayRef<ArgInfo> OrigArgs) const {
+                                    ArrayRef<ArgInfo> OrigArgs,
+                                    unsigned SwiftErrorVReg) const {
   MachineFunction &MF = MIRBuilder.getMF();
   const Function &F = MF.getFunction();
   MachineRegisterInfo &MRI = MF.getRegInfo();
@@ -503,6 +510,11 @@ bool AArch64CallLowering::lowerCall(MachineIRBuilder &MIRBuilder,
       MIRBuilder.buildSequence(OrigRet.Reg, SplitRegs, RegOffsets);
   }
 
+  if (SwiftErrorVReg) {
+    MIB.addDef(AArch64::X21, RegState::Implicit);
+    MIRBuilder.buildCopy(SwiftErrorVReg, AArch64::X21);
+  }
+
   CallSeqStart.addImm(Handler.StackSize).addImm(0);
   MIRBuilder.buildInstr(AArch64::ADJCALLSTACKUP)
       .addImm(Handler.StackSize)