[llvm] [X86][CostModel] Cost gathers by the instructions CodeGen emits (PR #220565)

[Sumukh J Bharadwaj via llvm-commits]

================
@@ -6633,50 +6667,97 @@ InstructionCost X86TTIImpl::getGSVectorCost(unsigned Opcode,
     const Value *Ptrs = GEP->getPointerOperand();
     if (Ptrs->getType()->isVectorTy() && !getSplatValue(Ptrs))
       return IndexSize;
-    for (unsigned I = 1, E = GEP->getNumOperands(); I != E; ++I) {
-      if (isa<Constant>(GEP->getOperand(I)))
+    for (gep_type_iterator GTI = gep_type_begin(GEP), GTE = gep_type_end(GEP);
+         GTI != GTE; ++GTI) {
+      const Value *Operand = GTI.getOperand();
+      if (isa<Constant>(Operand))
----------------
amd-subharad wrote:

Adopted. A constant that varies across lanes is now examined like any other index.

https://github.com/llvm/llvm-project/pull/220565