[llvm] AMDGPU/PromoteAlloca: Refactor into analysis / commit phases (PR #170512)

[via llvm-commits]

Nicolai =?utf-8?q?Hähnle?= <nicolai.haehnle at amd.com>,
Nicolai =?utf-8?q?Hähnle?= <nicolai.haehnle at amd.com>,
Nicolai =?utf-8?q?Hähnle?= <nicolai.haehnle at amd.com>,
Nicolai =?utf-8?q?Hähnle?= <nicolai.haehnle at amd.com>
Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/170512 at github.com>


================
@@ -388,23 +463,49 @@ static bool isSupportedMemset(MemSetInst *I, AllocaInst *AI,
          match(I->getOperand(2), m_SpecificInt(Size)) && !I->isVolatile();
 }
 
-static Value *calculateVectorIndex(
-    Value *Ptr, const std::map<GetElementPtrInst *, WeakTrackingVH> &GEPIdx) {
-  auto *GEP = dyn_cast<GetElementPtrInst>(Ptr->stripPointerCasts());
-  if (!GEP)
-    return ConstantInt::getNullValue(Type::getInt32Ty(Ptr->getContext()));
+static Value *calculateVectorIndex(Value *Ptr, AllocaAnalysis &AA) {
+  IRBuilder<> B(Ptr->getContext());
+
+  Ptr = Ptr->stripPointerCasts();
+  if (Ptr == AA.Alloca)
+    return B.getInt32(0);
+
+  auto *GEP = cast<GetElementPtrInst>(Ptr);
+  auto I = AA.Vector.GEPVectorIdx.find(GEP);
+  assert(I != AA.Vector.GEPVectorIdx.end() && "Must have entry for GEP!");
+
+  if (!I->second.Full) {
+    Value *Result = nullptr;
+    B.SetInsertPoint(GEP);
 
-  auto I = GEPIdx.find(GEP);
-  assert(I != GEPIdx.end() && "Must have entry for GEP!");
+    if (I->second.VarIndex) {
+      Result = I->second.VarIndex;
+      Result = B.CreateSExtOrTrunc(Result, B.getInt32Ty());
 
-  Value *IndexValue = I->second;
-  assert(IndexValue && "index value missing from GEP index map");
-  return IndexValue;
+      if (I->second.VarMul)
+        Result = B.CreateMul(Result, I->second.VarMul);
+    }
+
+    if (I->second.ConstIndex) {
+      if (Result) {
+        Result = B.CreateAdd(Result, I->second.ConstIndex);
+      } else {
+        Result = I->second.ConstIndex;
+      }
+    }
+
+    if (!Result)
+      Result = B.getInt32(0);
----------------
ruiling wrote:

I am not sure whether we can just assert here the `Result` is not null to catch unexpected error in the future. The assumption would be the pointer should either point to the alloca or the index should be passed explicitly.

https://github.com/llvm/llvm-project/pull/170512