WebAssembly: minor MCAsmInfo fixes

[jfb]

Summary

Fix pointer / callee-save stack sto size.
Update comment character to be LISP-ish.

[sunfish]

llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCAsmInfo.cpp

31

I'm ok using ';', but I suggest this comment just say something like "The s-expression format of WebAssembly uses LISP-style comments" since there may be other text formats, and since design justifications belong on the WebAssembly side rather than the LLVM side.

38

It looks like asm strings are by default printed with emitRawComment which includes the comment character and newline. Do we need to override the defaults for these strings?

[jfb]

Follow-up in D11544.

llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCAsmInfo.cpp

38

Ah you're right, fixed in follow-up.

llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCAsmInfo.cpp

 #include "llvm/Support/CommandLine.h"
 using namespace llvm;
 
 #define DEBUG_TYPE "wasm-mc-asm-info"
 
 WebAssemblyMCAsmInfo::~WebAssemblyMCAsmInfo() {}
 
 WebAssemblyMCAsmInfo::WebAssemblyMCAsmInfo(const Triple &T) {
-  PointerSize = CalleeSaveStackSlotSize = T.isArch64Bit();
+  PointerSize = CalleeSaveStackSlotSize = T.isArch64Bit() ? 8 : 4;
 
   // TODO: What should MaxInstLength be?
 
+  // WebAssembly's text format uses s-expressions to represent its AST,
+  // LISP-style comments are therefore suitable.
+  CommentString = ";";
+
   PrivateGlobalPrefix = "";
   PrivateLabelPrefix = "";
 
+  InlineAsmStart = ";APP\n";
+  InlineAsmEnd = ";NO_APP\n";
+
   UseDataRegionDirectives = true;
 
   Data8bitsDirective = "\t.int8\t";
   Data16bitsDirective = "\t.int16\t";
   Data32bitsDirective = "\t.int32\t";
   Data64bitsDirective = "\t.int64\t";
 
   AlignmentIsInBytes = false;