[llvm] [RISCV][TTI] Fix potential crash of using dyn_cast() in getIntrinsicInstrCost() NFC. (PR #109379)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-risc-v

Author: Elvis Wang (ElvisWang123)

<details>
<summary>Changes</summary>

This patch fix the potential crash about using dyn_cast in `vp_cmp` which is  same as #<!-- -->109313.

Check if the IntrinsicCostAttrubute contains underlying instruction first and cast to the VPCmpIntrinsic.

---
Full diff: https://github.com/llvm/llvm-project/pull/109379.diff


1 Files Affected:

- (modified) llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp (+3-3) 


``````````diff
diff --git a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
index 5d280b44630aef..d1cf7fc2991058 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
@@ -1039,12 +1039,12 @@ RISCVTTIImpl::getIntrinsicInstrCost(const IntrinsicCostAttributes &ICA,
   case Intrinsic::vp_fcmp: {
     Intrinsic::ID IID = ICA.getID();
     std::optional<unsigned> FOp = VPIntrinsic::getFunctionalOpcodeForVP(IID);
-    auto *UI = dyn_cast<VPCmpIntrinsic>(ICA.getInst());
-
     // We can only handle vp_cmp intrinsics with underlying instructions.
-    if (!UI)
+    if(!ICA.getInst())
       break;
+
     assert(FOp);
+    auto *UI = cast<VPCmpIntrinsic>(ICA.getInst());
     return getCmpSelInstrCost(*FOp, ICA.getArgTypes()[0], ICA.getReturnType(),
                               UI->getPredicate(), CostKind);
   }

``````````

</details>


https://github.com/llvm/llvm-project/pull/109379