[clang] [llvm] [ABI] Add CanBeFlattened to ArgInfo for Direct struct coerces (PR #220579)

[Steffen Larsen via cfe-commits]

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@@ -542,7 +543,9 @@ convertABIArgInfo(const llvm::abi::ArgInfo &info, MLIRContext *ctx,
     // trip for nothing.
     if (comparesAgainstCoerce && coerced == origTy)
       return ArgClassification::getDirect(nullptr);
-    return ArgClassification::getDirect(coerced);
+    ArgClassification classified = ArgClassification::getDirect(coerced);
+    classified.canFlatten = info.getCanBeFlattened();
+    return classified;
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steffenlarsen wrote:

Ah, my bad. I didn't realize it was different static members. Maybe unifying their signatures makes sense if they are related, but it is not a critical comment so if it's too far out of scope we can leave it as-is.

https://github.com/llvm/llvm-project/pull/220579