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

[Mikhail R. Gadelha via llvm-commits]

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

>From 948927e7998528b68378e4678bfbbf13dca3cdba Mon Sep 17 00:00:00 2001
From: "Mikhail R. Gadelha" <mikhail at igalia.com>
Date: Mon, 6 Jan 2025 15:39:46 -0300
Subject: [PATCH 1/2] [RISCV] Add missing check before accessing pointer

C2 can be null here, so we need to check it or clang may crash.
---
 llvm/lib/Target/RISCV/RISCVISelLowering.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

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) &&

>From 2446f48c72e37c202f6e02309c22f8ab1ef2bd54 Mon Sep 17 00:00:00 2001
From: "Mikhail R. Gadelha" <mikhail at igalia.com>
Date: Mon, 6 Jan 2025 18:35:47 -0300
Subject: [PATCH 2/2] Added test case

---
 .../CodeGen/RISCV/mul_sext_shl_constant.ll    | 33 +++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 llvm/test/CodeGen/RISCV/mul_sext_shl_constant.ll

diff --git a/llvm/test/CodeGen/RISCV/mul_sext_shl_constant.ll b/llvm/test/CodeGen/RISCV/mul_sext_shl_constant.ll
new file mode 100644
index 00000000000000..8f0b53e1144bde
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/mul_sext_shl_constant.ll
@@ -0,0 +1,33 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 3
+; RUN: llc -mtriple=riscv64 < %s | FileCheck -check-prefixes=NO-ZBA %s
+; RUN: llc -mtriple=riscv64 -mattr=+zba < %s | FileCheck -check-prefixes=ZBA %s
+
+define ptr @g(ptr %0, i32 %1) {
+; NO-ZBA-LABEL: g:
+; NO-ZBA:       # %bb.0:
+; NO-ZBA-NEXT:    slli a2, a1, 1
+; NO-ZBA-NEXT:    add a2, a2, a1
+; NO-ZBA-NEXT:    sllw a1, a2, a1
+; NO-ZBA-NEXT:    li a0, 0
+; NO-ZBA-NEXT:    ret
+;
+; ZBA-LABEL: g:
+; ZBA:       # %bb.0:
+; ZBA-NEXT:    sh1add a2, a1, a1
+; ZBA-NEXT:    sllw a1, a2, a1
+; ZBA-NEXT:    li a0, 0
+; ZBA-NEXT:    ret
+  %3 = mul i32 %1, 3
+  %4 = shl i32 %3, %1
+  %5 = sext i32 %4 to i64
+  %6 = inttoptr i64 %5 to ptr
+  %7 = icmp ugt ptr %0, %6
+  br i1 %7, label %10, label %8
+
+8:                                                ; preds = %2
+  %9 = load i8, ptr null, align 1
+  br label %10
+
+10:                                               ; preds = %8, %2
+  ret ptr null
+}