[llvm] [RISCV] Add missing check before accessing pointer (PR #121816)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

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

Author: Mikhail R. Gadelha (mikhailramalho)

<details>
<summary>Changes</summary>

C2 can be null here, so we need to check it or clang may crash.

---
Full diff: https://github.com/llvm/llvm-project/pull/121816.diff


1 Files Affected:

- (modified) llvm/lib/Target/RISCV/RISCVISelLowering.cpp (+1-1) 


``````````diff
diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index 7efe3732d8be13..9acd374225505d 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -18388,7 +18388,7 @@ bool RISCVTargetLowering::isDesirableToCommuteWithShift(
     auto *C2 = dyn_cast<ConstantSDNode>(N->getOperand(1));
 
     // Bail if we might break a sh{1,2,3}add pattern.
-    if (Subtarget.hasStdExtZba() && C2->getZExtValue() >= 1 &&
+    if (Subtarget.hasStdExtZba() && C2 && C2->getZExtValue() >= 1 &&
         C2->getZExtValue() <= 3 && N->hasOneUse() &&
         N->user_begin()->getOpcode() == ISD::ADD &&
         !isUsedByLdSt(*N->user_begin(), nullptr) &&

``````````

</details>


https://github.com/llvm/llvm-project/pull/121816