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/ImplicitNullChecks.cpp b/llvm/lib/CodeGen/ImplicitNullChecks.cpp
index 1e82ea6..b7dcaec 100644
--- a/llvm/lib/CodeGen/ImplicitNullChecks.cpp
+++ b/llvm/lib/CodeGen/ImplicitNullChecks.cpp
@@ -278,12 +278,12 @@
     if (!(MOA.isReg() && MOA.getReg()))
       continue;
 
-    unsigned RegA = MOA.getReg();
+    Register RegA = MOA.getReg();
     for (auto MOB : B->operands()) {
       if (!(MOB.isReg() && MOB.getReg()))
         continue;
 
-      unsigned RegB = MOB.getReg();
+      Register RegB = MOB.getReg();
 
       if (TRI->regsOverlap(RegA, RegB) && (MOA.isDef() || MOB.isDef()))
         return false;
@@ -517,7 +517,7 @@
   //
   // we must ensure that there are no instructions between the 'test' and
   // conditional jump that modify %rax.
-  const unsigned PointerReg = MBP.LHS.getReg();
+  const Register PointerReg = MBP.LHS.getReg();
 
   assert(MBP.ConditionDef->getParent() ==  &MBB && "Should be in basic block");
 
@@ -689,7 +689,7 @@
     for (const MachineOperand &MO : FaultingInstr->operands()) {
       if (!MO.isReg() || !MO.isDef())
         continue;
-      unsigned Reg = MO.getReg();
+      Register Reg = MO.getReg();
       if (!Reg || MBB->isLiveIn(Reg))
         continue;
       MBB->addLiveIn(Reg);