[AMDGPU] convert HIP struct type vector to llvm vector type (llvm#4344)

Author: JeniferC99

llvm/lib/Transforms/Scalar/SROA.cpp

@@ -83,6 +83,7 @@
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 #include "llvm/Transforms/Utils/Local.h"
+#include "llvm/TargetParser/Triple.h"
 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
 #include "llvm/Transforms/Utils/SSAUpdater.h"
 #include <algorithm>
@@ -4905,6 +4906,34 @@ AllocaInst *SROA::rewritePartition(AllocaInst &AI, AllocaSlices &AS,
     // FIXME: We might want to defer PHI speculation until after here.
     // FIXME: return nullptr;
   } else {
+    // AMDGPU: If the target is AMDGPU and the chosen SliceTy is a HIP vector
+    // struct of 2 or 4 identical elements, canonicalize it to an IR vector.
+    // This helps SROA treat it as a single value and unlock vector ld/st.
+    // We pattern-match struct names starting with "struct.HIP_vector".
+    if (Function *F = AI.getFunction()) {
+      Triple TT(F->getParent()->getTargetTriple());
+      if (TT.isAMDGPU()) {
+        if (auto *STy = dyn_cast<StructType>(SliceTy)) {
+          StringRef Name = STy->hasName() ? STy->getName() : StringRef();
+          if (Name.starts_with("struct.HIP_vector")) {
+            unsigned NumElts = STy->getNumElements();
+            if ((NumElts == 2 || NumElts == 4) && NumElts > 0) {
+              Type *EltTy = STy->getElementType(0);
+              bool AllSame = true;
+              for (unsigned I = 1; I < NumElts; ++I)
+                if (STy->getElementType(I) != EltTy) {
+                  AllSame = false;
+                  break;
+                }
+              if (AllSame && VectorType::isValidElementType(EltTy)) {
+                SliceTy = FixedVectorType::get(EltTy, NumElts);
+              }
+            }
+          }
+        }
+      }
+    }
+
     // Make sure the alignment is compatible with P.beginOffset().
     const Align Alignment = commonAlignment(AI.getAlign(), P.beginOffset());
     // If we will get at least this much alignment from the type alone, leave