[llvm] [WASM] Add support for memcmp expansion (PR #148298)

[via llvm-commits]

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@@ -141,6 +141,16 @@ InstructionCost WebAssemblyTTIImpl::getCastInstrCost(
   return BaseT::getCastInstrCost(Opcode, Dst, Src, CCH, CostKind, I);
 }
 
+WebAssemblyTTIImpl::TTI::MemCmpExpansionOptions
+WebAssemblyTTIImpl::enableMemCmpExpansion(bool OptSize, bool IsZeroCmp) const {
+  TTI::MemCmpExpansionOptions Options;
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badumbatish wrote:

how can i determine which p2align value is the right value? right now they're spitting out p2align 0, which I assume fits the comment for AllowOverlappingLoads?
```
    // requires all loads in LoadSizes to be doable in an unaligned way.
```

https://github.com/llvm/llvm-project/pull/148298