[llvm] [SLPVectorizer][X86] Free load cost for stores with constant pointers (PR #118016)

[Antonio Frighetto via llvm-commits]

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@@ -5157,8 +5157,9 @@ InstructionCost X86TTIImpl::getMemoryOpCost(unsigned Opcode, Type *Src,
 
   InstructionCost Cost = 0;
 
-  // Add a cost for constant load to vector.
-  if (Opcode == Instruction::Store && OpInfo.isConstant())
+  // Add a cost for constant load to vector, if pointer is not a constant.
+  if (auto *SI = dyn_cast_or_null<StoreInst>(I);
+      SI && !isa<Constant>(SI->getPointerOperand()) && OpInfo.isConstant())
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antoniofrighetto wrote:

That's correct. There is no cost for any constant load. There is only a memory address computation, which is _not_ a load.

https://github.com/llvm/llvm-project/pull/118016