Fix PR45442: Bail out when MemorySSA information is not available

llvm/lib/Transforms/Scalar/GVNHoist.cpp

@@ -521,6 +521,10 @@ private:
     if (NewPt == OldPt)
       return true;
 
+    // MemoryUseDef information is not available, bail out.
+    if (!U)
+      return false;
+
     const BasicBlock *NewBB = NewPt->getParent();
     const BasicBlock *OldBB = OldPt->getParent();
     const BasicBlock *UBB = U->getBlock();

llvm/test/Transforms/GVNHoist/pr45442.ll

@@ -0,0 +1,32 @@
+; RUN: opt < %s -gvn-hoist -S | FileCheck %s
+
+; gvn-hoist shouldn't crash in this case.
+; CHECK-LABEL: @func()
+; CHECK:       entry:
+; CHECK-NEXT:  br i1
+; CHECK:  bb1:
+; CHECK-NEXT:  unreachable
+; CHECK:  bb2:
+; CHECK-NEXT:  call
+; CHECK-NEXT:  call
+; CHECK-NEXT:  unreachable
+
+define void @v_1_0() #0 {
+entry:
+  ret void
+}
+
+define void @func()  {
+entry:
+  br i1 undef, label %bb1, label %bb2
+
+bb1:
+  unreachable
+
+bb2:
+  call void @v_1_0()
+  call void @v_1_0()
+  unreachable
+}
+
+attributes #0 = { nounwind readonly }