[llvm] [VPlan] First step towards VPlan cost modeling (LegacyCM in CostCtx) (PR #92555)
Florian Hahn via llvm-commits
llvm-commits at lists.llvm.org
Thu May 23 14:30:15 PDT 2024
================
@@ -730,6 +731,81 @@ void VPRegionBlock::execute(VPTransformState *State) {
State->Instance.reset();
}
+static InstructionCost computeCostForRecipe(VPRecipeBase *R, ElementCount VF,
+ VPCostContext &Ctx) {
+ Instruction *UI = nullptr;
+ if (auto *S = dyn_cast<VPSingleDefRecipe>(R))
+ UI = dyn_cast_or_null<Instruction>(S->getUnderlyingValue());
+ if (UI && Ctx.skipForCostComputation(UI))
+ return 0;
+
+ InstructionCost RecipeCost = R->computeCost(VF, Ctx);
+ if (ForceTargetInstructionCost.getNumOccurrences() > 0 &&
+ RecipeCost.isValid())
+ RecipeCost = InstructionCost(ForceTargetInstructionCost);
+
+ LLVM_DEBUG({
+ dbgs() << "Cost of " << RecipeCost << " for VF " << VF << ": ";
+ R->dump();
+ });
+ return RecipeCost;
+}
+
+InstructionCost VPBasicBlock::computeCost(ElementCount VF, VPCostContext &Ctx) {
+ InstructionCost Cost = 0;
+ for (VPRecipeBase &R : *this)
+ Cost += computeCostForRecipe(&R, VF, Ctx);
+ return Cost;
+}
+
+InstructionCost VPRegionBlock::computeCost(ElementCount VF,
+ VPCostContext &Ctx) {
+ InstructionCost Cost = 0;
+ if (!isReplicator()) {
+ for (VPBlockBase *Block : vp_depth_first_shallow(getEntry()))
+ Cost += Block->computeCost(VF, Ctx);
+ return Cost;
+ }
+
+ using namespace llvm::VPlanPatternMatch;
+ assert(isReplicator() && "can only compute cost for a replicator region");
+ VPBasicBlock *Then = cast<VPBasicBlock>(getEntry()->getSuccessors()[0]);
+ for (VPRecipeBase &R : *Then)
+ Cost += computeCostForRecipe(&R, VF, Ctx);
+
+ // Note the cost estimates below closely match the current legacy cost model.
+ auto *BOM = cast<VPBranchOnMaskRecipe>(&getEntryBasicBlock()->front());
+ VPValue *Cond = BOM->getOperand(0);
+
+ // Check if Cond is a uniform compare or a header mask.
+ VPValue *Op;
+ bool IsHeaderMaskOrUniformCond =
+ vputils::isUniformCompare(Cond) ||
+ match(Cond, m_ActiveLaneMask(m_VPValue(), m_VPValue())) ||
+ (match(Cond, m_Binary<Instruction::ICmp>(m_VPValue(), m_VPValue(Op))) &&
+ Op == getPlan()->getOrCreateBackedgeTakenCount()) ||
+ isa<VPActiveLaneMaskPHIRecipe>(Cond);
----------------
fhahn wrote:
moved, thanks!
https://github.com/llvm/llvm-project/pull/92555
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