Apply llvm-prefer-register-over-unsigned from clang-tidy to LLVM

Summary:
This clang-tidy check is looking for unsigned integer variables whose initializer
starts with an implicit cast from llvm::Register and changes the type of the
variable to llvm::Register (dropping the llvm:: where possible).

Partial reverts in:
X86FrameLowering.cpp - Some functions return unsigned and arguably should be MCRegister
X86FixupLEAs.cpp - Some functions return unsigned and arguably should be MCRegister
X86FrameLowering.cpp - Some functions return unsigned and arguably should be MCRegister
HexagonBitSimplify.cpp - Function takes BitTracker::RegisterRef which appears to be unsigned&
MachineVerifier.cpp - Ambiguous operator==() given MCRegister and const Register
PPCFastISel.cpp - No Register::operator-=()
PeepholeOptimizer.cpp - TargetInstrInfo::optimizeLoadInstr() takes an unsigned&
MachineTraceMetrics.cpp - MachineTraceMetrics lacks a suitable constructor

Manual fixups in:
ARMFastISel.cpp - ARMEmitLoad() now takes a Register& instead of unsigned&
HexagonSplitDouble.cpp - Ternary operator was ambiguous between unsigned/Register
HexagonConstExtenders.cpp - Has a local class named Register, used llvm::Register instead of Register.
PPCFastISel.cpp - PPCEmitLoad() now takes a Register& instead of unsigned&

Depends on D65919

Reviewers: arsenm, bogner, craig.topper, RKSimon

Reviewed By: arsenm

Subscribers: RKSimon, craig.topper, lenary, aemerson, wuzish, jholewinski, MatzeB, qcolombet, dschuff, jyknight, dylanmckay, sdardis, nemanjai, jvesely, wdng, nhaehnle, sbc100, jgravelle-google, kristof.beyls, hiraditya, aheejin, kbarton, fedor.sergeev, javed.absar, asb, rbar, johnrusso, simoncook, apazos, sabuasal, niosHD, jrtc27, MaskRay, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, tpr, PkmX, jocewei, jsji, Petar.Avramovic, asbirlea, Jim, s.egerton, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D65962

llvm-svn: 369041
diff --git a/llvm/lib/CodeGen/MIRCanonicalizerPass.cpp b/llvm/lib/CodeGen/MIRCanonicalizerPass.cpp
index 222432d..a9b4945 100644
--- a/llvm/lib/CodeGen/MIRCanonicalizerPass.cpp
+++ b/llvm/lib/CodeGen/MIRCanonicalizerPass.cpp
@@ -340,8 +340,8 @@
     if (!MI->getOperand(1).isReg())
       continue;
 
-    const unsigned Dst = MI->getOperand(0).getReg();
-    const unsigned Src = MI->getOperand(1).getReg();
+    const Register Dst = MI->getOperand(0).getReg();
+    const Register Src = MI->getOperand(1).getReg();
 
     if (!Register::isVirtualRegister(Dst))
       continue;
@@ -386,7 +386,7 @@
     bool DoesMISideEffect = false;
 
     if (MI->getNumOperands() > 0 && MI->getOperand(0).isReg()) {
-      const unsigned Dst = MI->getOperand(0).getReg();
+      const Register Dst = MI->getOperand(0).getReg();
       DoesMISideEffect |= !Register::isVirtualRegister(Dst);
 
       for (auto UI = MRI.use_begin(Dst); UI != MRI.use_end(); ++UI) {
@@ -754,7 +754,7 @@
   for (unsigned i = 0; i < IdempotentInstCount && MII != MBB->end(); ++i) {
     MachineInstr &MI = *MII++;
     Changed = true;
-    unsigned vRegToRename = MI.getOperand(0).getReg();
+    Register vRegToRename = MI.getOperand(0).getReg();
     auto Rename = NVC.createVirtualRegister(vRegToRename);
 
     std::vector<MachineOperand *> RenameMOs;