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

[Luke Lau via llvm-commits]

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@@ -141,6 +141,23 @@ 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;
+
+  Options.AllowOverlappingLoads = true;
+
+  // TODO: Teach WebAssembly backend about load v128.
+  // if (ST->hasSIMD128())
+  //   Options.LoadSizes.push_back(16);
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lukel97 wrote:

Nit, I don't really see commented out code in LLVM that often so I'd just leave it out

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