Support: Simplify endian stream interface. NFCI.

[pcc]

Summary

Provide some free functions to reduce verbosity of endian-writing
a single value, and replace the endianness template parameter with
a field.

Part of PR37466.

[pcc]

• Remove unused function

[ruiu]

LGTM

If I were to design this from scratch, I'd perhaps define two classes, LEWriter and BEWriter, instead of giving the endianness as an argument. But that's an off-topic.

[pcc]

In D47032#1104861, @ruiu wrote:

LGTM

If I were to design this from scratch, I'd perhaps define two classes, LEWriter and BEWriter, instead of giving the endianness as an argument. But that's an off-topic.

Maybe, but it will need to be an argument in a few other places, such as ELFObjectWriter (see D47040). Though maybe we could somehow template it on ELFT as we do in lld... but that's another separate discussion.

[zturner]

Note that the endianness values can be passed in to the llvm functions at
runtime, there are non template versions of the write functions that accept
endianness as arguments (that may be exactly what you used, btw, I didn’t
read the patch in detail).

It’s a shame this object hierarchy was developed separately from the
BinaryStream / StreamReader / StreamWriter interfaces, because it seems
like there’s some overlap and it would serve this use case nicely

wasm/WriterUtils.cpp

 
 void wasm::writeU8(raw_ostream &OS, uint8_t Byte, const Twine &Msg) {
   debugWrite(OS.tell(), Msg + " [0x" + utohexstr(Byte) + "]");
   OS << Byte;
 }
 
 void wasm::writeU32(raw_ostream &OS, uint32_t Number, const Twine &Msg) {
   debugWrite(OS.tell(), Msg + "[0x" + utohexstr(Number) + "]");
-  support::endian::Writer<support::little>(OS).write(Number);
+  support::endian::write(OS, Number, support::little);
 }
 
 void wasm::writeValueType(raw_ostream &OS, uint8_t Type, const Twine &Msg) {
   writeU8(OS, Type, Msg + "[type: " + valueTypeToString(Type) + "]");
 }
 
 void wasm::writeSig(raw_ostream &OS, const WasmSignature &Sig) {
   writeU8(OS, WASM_TYPE_FUNC, "signature type");