Author: eleviant Date: 2026-05-06T20:00:43+02:00 New Revision: a4ddeba8daff36c8e6285fa3603185b4c9b41718
URL: https://github.com/llvm/llvm-project/commit/a4ddeba8daff36c8e6285fa3603185b4c9b41718 DIFF: https://github.com/llvm/llvm-project/commit/a4ddeba8daff36c8e6285fa3603185b4c9b41718.diff LOG: [clang] Don't omit null pointer checks with -fms-kernel (#193800) In kernel space, a null (zero) address may be valid, so treating it as "always invalid" and bypassing null checks is not correct. With -fms-kernel, we override the default behavior and disable assumptions about null pointers. However, -fdelete-null-pointer-checks can still be used to re-enable these optimizations. Added: clang/test/CodeGen/MSKernel/null-deref.c Modified: clang/docs/ReleaseNotes.rst clang/include/clang/Options/Options.td Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index c2323b58a3e06..4de2b90cbabe5 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -291,6 +291,8 @@ Modified Compiler Flags - The `-mno-outline` and `-moutline` compiler flags are now allowed on RISC-V and X86, which both support the machine outliner. - The `-mno-outline` flag will now add the `nooutline` IR attribute, so that `-mno-outline` and `-moutline` objects can be mixed correctly during LTO. +- The `-fms-kernel` flag will now implicitly add -fno-delete-null-pointer-checks. + Still -fdelete-null-pointer-checks can be used to override this behavior. Removed Compiler Flags ---------------------- diff --git a/clang/include/clang/Options/Options.td b/clang/include/clang/Options/Options.td index e21ea8a6529a1..863e6b3d0871f 100644 --- a/clang/include/clang/Options/Options.td +++ b/clang/include/clang/Options/Options.td @@ -3037,10 +3037,10 @@ 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 0000000000000..f23409115f50d --- /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; +} _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
