[DSE] Remove getLocForWrite() (NFCI)

This implements nearly the same logic as getLocForWriteEx(), and
is only used in one place. In that context, we should also know
that getLocForWriteEx() returns a non-None result. As such,
consolidate everything to use one function.

diff --git a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
index 273ff25..f2268fe 100644 (file)
--- a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
@@ -205,39 +205,6 @@ static bool hasAnalyzableMemoryWrite(Instruction *I,
   return false;
 }
 
-/// Return a Location stored to by the specified instruction. If isRemovable
-/// returns true, this function and getLocForRead completely describe the memory
-/// operations for this instruction.
-static MemoryLocation getLocForWrite(Instruction *Inst,
-                                     const TargetLibraryInfo &TLI) {
-  if (StoreInst *SI = dyn_cast<StoreInst>(Inst))
-    return MemoryLocation::get(SI);
-
-  // memcpy/memmove/memset.
-  if (auto *MI = dyn_cast<AnyMemIntrinsic>(Inst))
-    return MemoryLocation::getForDest(MI);
-
-  if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
-    switch (II->getIntrinsicID()) {
-    default:
-      return MemoryLocation(); // Unhandled intrinsic.
-    case Intrinsic::init_trampoline:
-      return MemoryLocation::getAfter(II->getArgOperand(0));
-    case Intrinsic::masked_store:
-      return MemoryLocation::getForArgument(II, 1, TLI);
-    case Intrinsic::lifetime_end: {
-      uint64_t Len = cast<ConstantInt>(II->getArgOperand(0))->getZExtValue();
-      return MemoryLocation(II->getArgOperand(1), Len);
-    }
-    }
-  }
-  if (auto *CB = dyn_cast<CallBase>(Inst))
-    // All the supported TLI functions so far happen to have dest as their
-    // first argument.
-    return MemoryLocation::getAfter(CB->getArgOperand(0));
-  return MemoryLocation();
-}
-
 /// If the value of this instruction and the memory it writes to is unused, may
 /// we delete this instruction?
 static bool isRemovable(Instruction *I) {
@@ -1924,7 +1891,7 @@ struct DSEState {
     bool Changed = false;
     for (auto OI : IOL) {
       Instruction *DeadI = OI.first;
-      MemoryLocation Loc = getLocForWrite(DeadI, TLI);
+      MemoryLocation Loc = *getLocForWriteEx(DeadI);
       assert(isRemovable(DeadI) && "Expect only removable instruction");
 
       const Value *Ptr = Loc.Ptr->stripPointerCasts();