[llvm] [VPlan] First step towards VPlan cost modeling. (PR #92555)

[Florian Hahn via llvm-commits]

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@@ -7300,6 +7295,161 @@ LoopVectorizationPlanner::plan(ElementCount UserVF, unsigned UserIC) {
   return VF;
 }
 
+InstructionCost VPCostContext::getLegacyCost(Instruction *UI,
+                                             ElementCount VF) const {
+  return CM.getInstructionCost(UI, VF).first;
+}
+
+InstructionCost VPCostContext::getLoopExitCost(ElementCount VF) {
+  SmallVector<BasicBlock *> Exiting;
+  CM.TheLoop->getExitingBlocks(Exiting);
+  InstructionCost Cost = 0;
+  // Add the cost of all exit conditions.
+  for (BasicBlock *EB : Exiting) {
+    auto *Term = dyn_cast<BranchInst>(EB->getTerminator());
+    if (!Term)
+      continue;
+    if (auto *CondI = dyn_cast<Instruction>(Term->getOperand(0))) {
+      SkipCostComputation.insert(CondI);
+      Cost += CM.getInstructionCost(CondI, VF).first;
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fhahn wrote:

Yes, the original exit conditions are DCE'd by VPlan transforms if they are only used to control the exit.

https://github.com/llvm/llvm-project/pull/92555