[llvm] [RISCV][CostModel] VPIntrinsics have same cost as their non-vp counterparts (PR #67178)

[Craig Topper via llvm-commits]

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@@ -1687,6 +1687,60 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {
     }
     }
 
+    // VP Intrinsics should have the same cost as their non-vp counterpart.
+    // TODO: Adjust the cost to make the vp intrinsic cheaper than its non-vp
+    // counterpart when the vector length argument is smaller than the maximum
+    // vector length.
+    if (VPIntrinsic::isVPIntrinsic(ICA.getID())) {
+      std::optional<unsigned> FOp =
+          VPIntrinsic::getFunctionalOpcodeForVP(ICA.getID());
+      if (FOp) {
+        // TODO: Support other kinds of Intrinsics (i.e. reductions)
+        if (ICA.getID() == Intrinsic::vp_load) {
+          Align Alignment;
+          if (auto *VPI = dyn_cast_or_null<VPIntrinsic>(ICA.getInst()))
+            Alignment = VPI->getPointerAlignment().valueOrOne();
+          unsigned AS = 0;
+          if (ICA.getArgs().size() > 1)
+            if (auto PtrTy = dyn_cast<PointerType>(ICA.getArgs()[0]->getType()))
+              AS = PtrTy->getAddressSpace();
+          return thisT()->getMemoryOpCost(*FOp, ICA.getReturnType(), Alignment,
+                                          AS, CostKind);
+        } else if (ICA.getID() == Intrinsic::vp_store) {
+          Align Alignment;
+          if (auto *VPI = dyn_cast_or_null<VPIntrinsic>(ICA.getInst()))
+            Alignment = VPI->getPointerAlignment().valueOrOne();
+          unsigned AS = 0;
+          if (ICA.getArgs().size() >= 2)
+            if (auto PtrTy = dyn_cast<PointerType>(ICA.getArgs()[1]->getType()))
+              AS = PtrTy->getAddressSpace();
+          return thisT()->getMemoryOpCost(*FOp, Args[0]->getType(), Alignment,
+                                          AS, CostKind);
+        } else if (VPBinOpIntrinsic::isVPBinOp(ICA.getID())) {
+          return thisT()->getArithmeticInstrCost(*FOp, ICA.getReturnType(),
+                                                 CostKind);
+        }
+      }
+
+      std::optional<Intrinsic::ID> FID =
+          VPIntrinsic::getFunctionalIntrinsicIDForVP(ICA.getID());
+      if (FID) {
+        // Non-vp version will have same Args/Tys except mask and vector length.
+        assert(ICA.getArgs().size() >= 2 && ICA.getArgTypes().size() >= 2 &&
+               "Expected VPIntrinsic to have Mask and Vector Length args and "
+               "types");
+        ArrayRef<const Value *> NewArgs(ICA.getArgs().begin(),
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topperc wrote:

Can we do `ArrayRef(ICA.getArgs()).drop_back(2)`?

https://github.com/llvm/llvm-project/pull/67178