From 92a39aa4c8158270a67362944a826ba51287441d Mon Sep 17 00:00:00 2001
From: Evgeny Leviant <eleviant@accesssoftek.com>
Date: Thu, 9 Apr 2026 11:58:30 +0200
Subject: [PATCH] Don't omit null pointer checks with -fms-kernel

---
 clang/include/clang/Driver/Options.td    |  4 ++--
 clang/test/CodeGen/MSKernel/null-deref.c | 16 ++++++++++++++++
 2 files changed, 18 insertions(+), 2 deletions(-)
 create mode 100644 clang/test/CodeGen/MSKernel/null-deref.c

diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 4eb013d587eb..029e8fbf7c7c 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -2732,10 +2732,10 @@ defm rewrite_includes : BoolFOption<"rewrite-includes",
 defm directives_only : OptInCC1FFlag<"directives-only", "">;
 
 defm delete_null_pointer_checks : BoolFOption<"delete-null-pointer-checks",
-  CodeGenOpts<"NullPointerIsValid">, DefaultFalse,
+  CodeGenOpts<"NullPointerIsValid">, Default<"LangOpts->Kernel">,
   NegFlag<SetTrue, [], [ClangOption, CC1Option],
           "Do not treat usage of null pointers as undefined behavior">,
-  PosFlag<SetFalse, [], [ClangOption], "Treat usage of null pointers as undefined behavior (default)">,
+  PosFlag<SetFalse, [], [ClangOption, CC1Option], "Treat usage of null pointers as undefined behavior (default)">,
   BothFlags<[], [ClangOption, CLOption]>>,
   DocBrief<[{When enabled, treat null pointer dereference, creation of a reference to null,
 or passing a null pointer to a function parameter annotated with the "nonnull"
diff --git a/clang/test/CodeGen/MSKernel/null-deref.c b/clang/test/CodeGen/MSKernel/null-deref.c
new file mode 100644
index 000000000000..f23409115f50
--- /dev/null
+++ b/clang/test/CodeGen/MSKernel/null-deref.c
@@ -0,0 +1,16 @@
+// Check that null pointer checks are not omited in kernel mode compilations
+// RUN: %clang_cc1 -fms-kernel -fms-extensions -triple x86_64-pc-windows-msvc %s -emit-llvm -o - | FileCheck %s
+// RUN: %clang_cc1 -fms-kernel -fms-extensions -triple x86_64-pc-windows-msvc -fdelete-null-pointer-checks %s -emit-llvm -o - | FileCheck %s --check-prefix=NOCHECK
+
+// CHECK: define dso_local i32 @process(ptr noundef %p) #0
+// CHECK: attributes #0 = {{.*}} null_pointer_is_valid
+// NOCHECK-NOT: null_pointer_is_valid
+
+struct Obj { int value; int extra; };
+
+int process(struct Obj* p) {
+    int v = p->value;
+    if (!p)
+        return -1;
+    return v + p->extra;
+}