[llvm] [Loads] Fix crash in isSafeToLoadUnconditionally with scalable accessed type (PR #82650)

[Nikita Popov via llvm-commits]

================
@@ -0,0 +1,22 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
+; RUN: opt < %s -passes=vector-combine -S -mtriple=riscv32 -mattr=+v | FileCheck %s -check-prefixes=CHECK,RV32
+; RUN: opt < %s -passes=vector-combine -S -mtriple=riscv64 -mattr=+v | FileCheck %s -check-prefixes=CHECK,RV64
+
+define void @fixed_load_scalable_src() {
+; CHECK-LABEL: define void @fixed_load_scalable_src(
+; CHECK-SAME: ) #[[ATTR0:[0-9]+]] {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    store <vscale x 4 x i16> zeroinitializer, ptr null, align 8
+; CHECK-NEXT:    [[TMP0:%.*]] = load <4 x i16>, ptr null, align 8
+; CHECK-NEXT:    [[TMP1:%.*]] = shufflevector <4 x i16> [[TMP0]], <4 x i16> zeroinitializer, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 poison, i32 poison, i32 poison, i32 poison>
+; CHECK-NEXT:    ret void
+;
+entry:
+  store <vscale x 4 x i16> zeroinitializer, ptr null
----------------
nikic wrote:

Please use a proper pointer argument instead of `ptr null` to avoid insta-UB.

https://github.com/llvm/llvm-project/pull/82650