[llvm] Add utility function for collecting pointer operands of memory-access instructions. (PR #172616)

[Nikita Popov via llvm-commits]

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@@ -5196,6 +5196,38 @@ inline void setAtomicSyncScopeID(Instruction *I, SyncScope::ID SSID) {
     llvm_unreachable("unhandled atomic operation");
 }
 
+/// A helper function that returns the pointer operands of a memory-access
+/// instruction.
+inline std::optional<SmallVector<const Value *, 2u>>
+getMemAccessOperands(const Instruction *I) {
+  if (const LoadInst *LI = dyn_cast<LoadInst>(I))
+    return {{LI->getPointerOperand()}};
+  if (const StoreInst *SI = dyn_cast<StoreInst>(I))
+    return {{SI->getPointerOperand()}};
+  if (const VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
+    return {{VAAI->getPointerOperand()}};
+  if (const AtomicCmpXchgInst *CXI = dyn_cast<AtomicCmpXchgInst>(I))
+    return {{CXI->getPointerOperand()}};
+  if (const AtomicRMWInst *RMWI = dyn_cast<AtomicRMWInst>(I))
+    return {{RMWI->getPointerOperand()}};
+  if (const auto *Call = dyn_cast<CallBase>(I)) {
+    if (Call->doesNotAccessMemory())
+      return std::nullopt;
+
+    SmallVector<const Value *, 2u> PtrArgs;
+    for (Value *Arg : Call->args()) {
+      if (!Arg->getType()->isPointerTy())
+        continue;
+
+      PtrArgs.push_back(Arg);
+    }
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nikic wrote:

I don't think you should be conflating the basic load/store with the call case. The call case requires special handling depending on context.

https://github.com/llvm/llvm-project/pull/172616