[Wasm RyuJIT] Fix classifier embiggening small structs that are being passed-as a wasm primitive

[kg]

Addresses part of #125199

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[Copilot]

Pull request overview

Adjusts Wasm ABI classification for small structs that are lowered to Wasm primitive types to avoid size/type mismatches during local stack stores (part of #125199).

Changes:

• Compute the ABI passing segment size for lowered structs using the struct’s actual size (capped by the ABI primitive size) instead of always using the primitive size.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 1 comment.

[Copilot]

When passByRef is false, using min(structLayout->GetSize(), genTypeSize(abiType)) can silently truncate the recorded segment size if getWasmLowering ever returns a wasm primitive that’s smaller than the actual struct size. That would mask a classifier/EE mismatch and could lead to incorrect copying later; consider using structLayout->GetSize() directly and adding a debug assert that it fits in genTypeSize(abiType) instead of clamping.

Suggested change

	unsigned segmentSize = passByRef ? genTypeSize(abiType) : min(structLayout->GetSize(), genTypeSize(abiType));
	unsigned abiTypeSize = genTypeSize(abiType);
	unsigned segmentSize;
	if (passByRef)
	{
	segmentSize = abiTypeSize;
	}
	else
	{
	unsigned structSize = structLayout->GetSize();
	assert(structSize <= abiTypeSize);
	segmentSize = structSize;
	}