[MIR-Canon] Add support for rewriting VRegs that are typed but don't have an RC.

There were crashes (addrspace-memoperands.mir was only one of them) in MIR that
had operands that came from before register classes were set. With these
operands, creating a replacement vreg (for MIR-Canon's renaming) needs to use
the vreg type rather than the RegisterClass which is not present.

Differential Revision: https://reviews.llvm.org/D62543

llvm-svn: 362122

Author: plotfi

llvm/lib/CodeGen/MIRCanonicalizerPass.cpp

@@ -500,14 +500,15 @@ class NamedVRegCursor {
     return virtualVRegNumber;
   }
 
-  unsigned createVirtualRegister(const TargetRegisterClass *RC) {
+  unsigned createVirtualRegister(unsigned VReg) {
     std::string S;
     raw_string_ostream OS(S);
     OS << "namedVReg" << (virtualVRegNumber & ~0x80000000);
     OS.flush();
     virtualVRegNumber++;
-
-    return MRI.createVirtualRegister(RC, OS.str());
+    if (auto RC = MRI.getRegClassOrNull(VReg))
+      return MRI.createVirtualRegister(RC, OS.str());
+    return MRI.createGenericVirtualRegister(MRI.getType(VReg), OS.str());
   }
 };
 } // namespace
@@ -557,7 +558,7 @@ GetVRegRenameMap(const std::vector<TypedVReg> &VRegs,
       continue;
     }
 
-    auto Rename = NVC.createVirtualRegister(MRI.getRegClass(Reg));
+    auto Rename = NVC.createVirtualRegister(Reg);
 
     if (VRegRenameMap.find(Reg) == VRegRenameMap.end()) {
       LLVM_DEBUG(dbgs() << "Mapping vreg ";);
@@ -741,7 +742,7 @@ static bool runOnBasicBlock(MachineBasicBlock *MBB,
     MachineInstr &MI = *MII++;
     Changed = true;
     unsigned vRegToRename = MI.getOperand(0).getReg();
-    auto Rename = NVC.createVirtualRegister(MRI.getRegClass(vRegToRename));
+    auto Rename = NVC.createVirtualRegister(vRegToRename);
 
     std::vector<MachineOperand *> RenameMOs;
     for (auto &MO : MRI.reg_operands(vRegToRename)) {

llvm/test/CodeGen/MIR/AArch64/addrspace-memoperands.mir

@@ -1,4 +1,5 @@
 # RUN: llc -mtriple=aarch64-none-linux-gnu -run-pass none -o - %s | FileCheck %s
+# RUN: llc -mtriple=aarch64-none-linux-gnu -run-pass mir-canonicalizer -o - %s
 
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