[WebAssembly] clang-tidy (NFC)

Summary:
This patch fixes clang-tidy warnings on wasm-only files.
The list of checks used is:
`-*,clang-diagnostic-*,llvm-*,misc-*,-misc-unused-parameters,readability-identifier-naming,modernize-*`
(LLVM's default .clang-tidy list is the same except it does not have
`modernize-*`. But I've seen in multiple CLs in LLVM the modernize style
was recommended and code was fixed based on the style, so I added it as
well.)

The common fixes are:
- Variable names start with an uppercase letter
- Function names start with a lowercase letter
- Use `auto` when you use casts so the type is evident
- Use inline initialization for class member variables
- Use `= default` for empty constructors / destructors
- Use `using` in place of `typedef`

Reviewers: sbc100, tlively, aardappel

Subscribers: dschuff, sunfish, jgravelle-google, yurydelendik, kripken, MatzeB, mgorny, rupprecht, llvm-commits

Differential Revision: https://reviews.llvm.org/D57500

llvm-svn: 353075
diff --git a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCCodeEmitter.cpp b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCCodeEmitter.cpp
index b7bcb7c..8d89c56 100644
--- a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCCodeEmitter.cpp
+++ b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCCodeEmitter.cpp
@@ -48,7 +48,7 @@
                          const MCSubtargetInfo &STI) const override;
 
 public:
-  WebAssemblyMCCodeEmitter(const MCInstrInfo &mcii) : MCII(mcii) {}
+  WebAssemblyMCCodeEmitter(const MCInstrInfo &MCII) : MCII(MCII) {}
 };
 } // end anonymous namespace
 
@@ -81,14 +81,14 @@
     encodeULEB128(MI.getNumOperands() - 2, OS);
 
   const MCInstrDesc &Desc = MCII.get(MI.getOpcode());
-  for (unsigned i = 0, e = MI.getNumOperands(); i < e; ++i) {
-    const MCOperand &MO = MI.getOperand(i);
+  for (unsigned I = 0, E = MI.getNumOperands(); I < E; ++I) {
+    const MCOperand &MO = MI.getOperand(I);
     if (MO.isReg()) {
       /* nothing to encode */
 
     } else if (MO.isImm()) {
-      if (i < Desc.getNumOperands()) {
-        const MCOperandInfo &Info = Desc.OpInfo[i];
+      if (I < Desc.getNumOperands()) {
+        const MCOperandInfo &Info = Desc.OpInfo[I];
         LLVM_DEBUG(dbgs() << "Encoding immediate: type="
                           << int(Info.OperandType) << "\n");
         switch (Info.OperandType) {
@@ -126,20 +126,20 @@
       }
 
     } else if (MO.isFPImm()) {
-      const MCOperandInfo &Info = Desc.OpInfo[i];
+      const MCOperandInfo &Info = Desc.OpInfo[I];
       if (Info.OperandType == WebAssembly::OPERAND_F32IMM) {
         // TODO: MC converts all floating point immediate operands to double.
         // This is fine for numeric values, but may cause NaNs to change bits.
-        float f = float(MO.getFPImm());
-        support::endian::write<float>(OS, f, support::little);
+        auto F = float(MO.getFPImm());
+        support::endian::write<float>(OS, F, support::little);
       } else {
         assert(Info.OperandType == WebAssembly::OPERAND_F64IMM);
-        double d = MO.getFPImm();
-        support::endian::write<double>(OS, d, support::little);
+        double D = MO.getFPImm();
+        support::endian::write<double>(OS, D, support::little);
       }
 
     } else if (MO.isExpr()) {
-      const MCOperandInfo &Info = Desc.OpInfo[i];
+      const MCOperandInfo &Info = Desc.OpInfo[I];
       llvm::MCFixupKind FixupKind;
       size_t PaddedSize = 5;
       switch (Info.OperandType) {