[clang] [Clang][RISCV] Handle RVV tuple types correctly as OutputOperands for inline asm (PR #67018)

[Yueh-Ting Chen via cfe-commits]

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@@ -2524,11 +2551,32 @@ void CodeGenFunction::EmitAsmStmt(const AsmStmt &S) {
       ResultRegIsFlagReg.push_back(IsFlagReg);
 
       llvm::Type *Ty = ConvertTypeForMem(QTy);
+      ResultTruncRegTypes.push_back(Ty);
+
+      // Expressing the type as a structure in inline asm calls will complicate
+      // the current code case, so instead, the return type is set to be a
+      // single scalable vector, then reconstructed with `vector.extract` and
+      // `insertvalue`. The type is derived here, and the reconstruction is done
+      // under EmitAsmStores.
+      if (QTy->isRVVType() && isa<llvm::StructType>(Ty)) {
+        // Flatten the structure into a single ScalableVectorType
+        auto *STy = cast<llvm::StructType>(Ty);
+        assert(STy->containsHomogeneousScalableVectorTypes() &&
+               isa<llvm::ScalableVectorType>(STy->getElementType(0)) &&
+               "Dealing with RVV tuple (aggregate with homogeneous scalable "
+               "vectors");
+
+        auto *VecTy = cast<llvm::ScalableVectorType>(STy->getElementType(0));
+
+        Ty = llvm::ScalableVectorType::get(VecTy->getScalarType(),
+                                           STy->getNumElements() *
+                                               VecTy->getMinNumElements());
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eopXD wrote:

Yes, the initial approach will fall into this hazard. The updated approach to have them as the structure type we are expecting will avoid falling into this problem.

https://github.com/llvm/llvm-project/pull/67018