[clang]: Add support for "-fno-delete-null-pointer-checks"

Summary:
Support for this option is needed for building Linux kernel.
This is a very frequently requested feature by kernel developers.

More details : https://lkml.org/lkml/2018/4/4/601

GCC option description for -fdelete-null-pointer-checks:
This Assume that programs cannot safely dereference null pointers,
and that no code or data element resides at address zero.

-fno-delete-null-pointer-checks is the inverse of this implying that
null pointer dereferencing is not undefined.

This feature is implemented in as the function attribute
"null-pointer-is-valid"="true".
This CL only adds the attribute on the function.
It also strips "nonnull" attributes from function arguments but
keeps the related warnings unchanged.

Corresponding LLVM change rL336613 already updated the
optimizations to not treat null pointer dereferencing
as undefined if the attribute is present.

Reviewers: t.p.northover, efriedma, jyknight, chandlerc, rnk, srhines, void, george.burgess.iv

Reviewed By: jyknight

Subscribers: drinkcat, xbolva00, cfe-commits

Differential Revision: https://reviews.llvm.org/D47894

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@337433 91177308-0d34-0410-b5e6-96231b3b80d8

docs/ClangCommandLineReference.rst

@@ -1543,6 +1543,14 @@ Specifies the largest alignment guaranteed by '::operator new(size\_t)'
 
 Disable implicit builtin knowledge of a specific function
 
+.. option:: -fdelete-null-pointer-checks, -fno-delete-null-pointer-checks
+
+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"
+attribute as undefined behavior. (And, thus the optimizer may assume that any
+pointer used in such a way must not have been null and optimize away the
+branches accordingly.) On by default.
+
 .. option:: -fno-elide-type
 
 Do not elide types when printing diagnostics

include/clang/Driver/Options.td

@@ -1080,6 +1080,13 @@ def frewrite_imports : Flag<["-"], "frewrite-imports">, Group<f_Group>,
   Flags<[CC1Option]>;
 def fno_rewrite_imports : Flag<["-"], "fno-rewrite-imports">, Group<f_Group>;
 
+def fdelete_null_pointer_checks : Flag<["-"],
+  "fdelete-null-pointer-checks">, Group<f_Group>,
+  HelpText<"Treat usage of null pointers as undefined behavior.">;
+def fno_delete_null_pointer_checks : Flag<["-"],
+  "fno-delete-null-pointer-checks">, Group<f_Group>, Flags<[CC1Option]>,
+  HelpText<"Do not treat usage of null pointers as undefined behavior.">;
+
 def frewrite_map_file : Separate<["-"], "frewrite-map-file">,
                         Group<f_Group>,
                         Flags<[ DriverOption, CC1Option ]>;
@@ -2855,8 +2862,6 @@ defm reorder_blocks : BooleanFFlag<"reorder-blocks">, Group<clang_ignored_gcc_op
 defm eliminate_unused_debug_types : BooleanFFlag<"eliminate-unused-debug-types">, Group<clang_ignored_f_Group>;
 defm branch_count_reg : BooleanFFlag<"branch-count-reg">, Group<clang_ignored_gcc_optimization_f_Group>;
 defm default_inline : BooleanFFlag<"default-inline">, Group<clang_ignored_gcc_optimization_f_Group>;
-defm delete_null_pointer_checks : BooleanFFlag<"delete-null-pointer-checks">,
-    Group<clang_ignored_gcc_optimization_f_Group>;
 defm fat_lto_objects : BooleanFFlag<"fat-lto-objects">, Group<clang_ignored_gcc_optimization_f_Group>;
 defm float_store : BooleanFFlag<"float-store">, Group<clang_ignored_gcc_optimization_f_Group>;
 defm friend_injection : BooleanFFlag<"friend-injection">, Group<clang_ignored_f_Group>;

include/clang/Frontend/CodeGenOptions.def

@@ -130,6 +130,7 @@ CODEGENOPT(EnableSegmentedStacks , 1, 0) ///< Set when -fsplit-stack is enabled.
 CODEGENOPT(NoImplicitFloat   , 1, 0) ///< Set when -mno-implicit-float is enabled.
 CODEGENOPT(NoInfsFPMath      , 1, 0) ///< Assume FP arguments, results not +-Inf.
 CODEGENOPT(NoSignedZeros     , 1, 0) ///< Allow ignoring the signedness of FP zero
+CODEGENOPT(NullPointerIsValid , 1, 0) ///< Assume Null pointer deference is defined.
 CODEGENOPT(Reassociate       , 1, 0) ///< Allow reassociation of FP math ops
 CODEGENOPT(ReciprocalMath    , 1, 0) ///< Allow FP divisions to be reassociated.
 CODEGENOPT(NoTrappingMath    , 1, 0) ///< Set when -fno-trapping-math is enabled.

lib/CodeGen/CGCall.cpp

@@ -1734,6 +1734,8 @@ void CodeGenModule::ConstructDefaultFnAttrList(StringRef Name, bool HasOptnone,
     FuncAttrs.addAttribute("less-precise-fpmad",
                            llvm::toStringRef(CodeGenOpts.LessPreciseFPMAD));
 
+    if (CodeGenOpts.NullPointerIsValid)
+      FuncAttrs.addAttribute("null-pointer-is-valid", "true");
     if (!CodeGenOpts.FPDenormalMode.empty())
       FuncAttrs.addAttribute("denormal-fp-math", CodeGenOpts.FPDenormalMode);
 
@@ -1867,7 +1869,8 @@ void CodeGenModule::ConstructAttributeList(
     }
     if (TargetDecl->hasAttr<RestrictAttr>())
       RetAttrs.addAttribute(llvm::Attribute::NoAlias);
-    if (TargetDecl->hasAttr<ReturnsNonNullAttr>())
+    if (TargetDecl->hasAttr<ReturnsNonNullAttr>() &&
+        !CodeGenOpts.NullPointerIsValid)
       RetAttrs.addAttribute(llvm::Attribute::NonNull);
     if (TargetDecl->hasAttr<AnyX86NoCallerSavedRegistersAttr>())
       FuncAttrs.addAttribute("no_caller_saved_registers");
@@ -1974,7 +1977,8 @@ void CodeGenModule::ConstructAttributeList(
     if (!PTy->isIncompleteType() && PTy->isConstantSizeType())
       RetAttrs.addDereferenceableAttr(getContext().getTypeSizeInChars(PTy)
                                         .getQuantity());
-    else if (getContext().getTargetAddressSpace(PTy) == 0)
+    else if (getContext().getTargetAddressSpace(PTy) == 0 &&
+             !CodeGenOpts.NullPointerIsValid)
       RetAttrs.addAttribute(llvm::Attribute::NonNull);
   }
 
@@ -2083,7 +2087,8 @@ void CodeGenModule::ConstructAttributeList(
       if (!PTy->isIncompleteType() && PTy->isConstantSizeType())
         Attrs.addDereferenceableAttr(getContext().getTypeSizeInChars(PTy)
                                        .getQuantity());
-      else if (getContext().getTargetAddressSpace(PTy) == 0)
+      else if (getContext().getTargetAddressSpace(PTy) == 0 &&
+               !CodeGenOpts.NullPointerIsValid)
         Attrs.addAttribute(llvm::Attribute::NonNull);
     }
 
@@ -2343,7 +2348,8 @@ void CodeGenFunction::EmitFunctionProlog(const CGFunctionInfo &FI,
 
         if (const ParmVarDecl *PVD = dyn_cast<ParmVarDecl>(Arg)) {
           if (getNonNullAttr(CurCodeDecl, PVD, PVD->getType(),
-                             PVD->getFunctionScopeIndex()))
+                             PVD->getFunctionScopeIndex()) &&
+              !CGM.getCodeGenOpts().NullPointerIsValid)
             AI->addAttr(llvm::Attribute::NonNull);
 
           QualType OTy = PVD->getOriginalType();
@@ -2362,7 +2368,8 @@ void CodeGenFunction::EmitFunctionProlog(const CGFunctionInfo &FI,
                 Attrs.addDereferenceableAttr(
                   getContext().getTypeSizeInChars(ETy).getQuantity()*ArrSize);
                 AI->addAttrs(Attrs);
-              } else if (getContext().getTargetAddressSpace(ETy) == 0) {
+              } else if (getContext().getTargetAddressSpace(ETy) == 0 &&
+                         !CGM.getCodeGenOpts().NullPointerIsValid) {
                 AI->addAttr(llvm::Attribute::NonNull);
               }
             }
@@ -2372,7 +2379,8 @@ void CodeGenFunction::EmitFunctionProlog(const CGFunctionInfo &FI,
             // we can't use the dereferenceable attribute, but in addrspace(0)
             // we know that it must be nonnull.
             if (ArrTy->getSizeModifier() == VariableArrayType::Static &&
-                !getContext().getTargetAddressSpace(ArrTy->getElementType()))
+                !getContext().getTargetAddressSpace(ArrTy->getElementType()) &&
+                !CGM.getCodeGenOpts().NullPointerIsValid)
               AI->addAttr(llvm::Attribute::NonNull);
           }
 

lib/Driver/ToolChains/Clang.cpp

@@ -3348,6 +3348,10 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
                    options::OPT_fno_merge_all_constants, false))
     CmdArgs.push_back("-fmerge-all-constants");
 
+  if (Args.hasFlag(options::OPT_fno_delete_null_pointer_checks,
+                   options::OPT_fdelete_null_pointer_checks, false))
+    CmdArgs.push_back("-fno-delete-null-pointer-checks");
+
   // LLVM Code Generator Options.
 
   if (Args.hasArg(options::OPT_frewrite_map_file) ||

lib/Frontend/CompilerInvocation.cpp

@@ -746,6 +746,8 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
 
   Opts.NoUseJumpTables = Args.hasArg(OPT_fno_jump_tables);
 
+  Opts.NullPointerIsValid = Args.hasArg(OPT_fno_delete_null_pointer_checks);
+
   Opts.ProfileSampleAccurate = Args.hasArg(OPT_fprofile_sample_accurate);
 
   Opts.PrepareForLTO = Args.hasArg(OPT_flto, OPT_flto_EQ);

test/CodeGen/delete-null-pointer-checks.c

@@ -0,0 +1,20 @@
+// RUN: %clang_cc1 -emit-llvm -triple x86_64-unknown-linux-gnu -O2 -o - %s | FileCheck -check-prefix=NULL-POINTER-INVALID  %s
+// RUN: %clang_cc1 -emit-llvm -triple x86_64-unknown-linux-gnu -O2 -o - %s -fno-delete-null-pointer-checks | FileCheck -check-prefix=NULL-POINTER-VALID  %s
+
+// Test that clang does not remove the null pointer check with
+// -fno-delete-null-pointer-checks.
+int null_check(int *P) {
+// NULL-POINTER-VALID: %[[TOBOOL:.*]] = icmp eq i32* %P, null
+// NULL-POINTER-INVALID-NOT: icmp eq
+// NULL-POINTER-VALID: %[[SEL:.*]] = select i1 %[[TOBOOL:.*]], i32* null, i32*
+// NULL-POINTER-INVALID-NOT: select i1
+// NULL-POINTER-VALID: load i32, i32* %[[SEL:.*]]
+  int *Q = P;
+  if (P) {
+    Q = P + 2;
+  }
+  return *Q;
+}
+
+// NULL-POINTER-INVALID-NOT: attributes #0 = {{.*}} "null-pointer-is-valid"="true"
+// NULL-POINTER-VALID: attributes #0 = {{.*}} "null-pointer-is-valid"="true"

test/CodeGen/nonnull.c

@@ -1,32 +1,39 @@
-// RUN: %clang_cc1 -triple x86_64-apple-darwin -emit-llvm < %s | FileCheck %s
+// RUN: %clang_cc1 -triple x86_64-apple-darwin -emit-llvm < %s | FileCheck -check-prefix=NULL-INVALID %s
+// RUN: %clang_cc1 -triple x86_64-apple-darwin -emit-llvm -fno-delete-null-pointer-checks < %s | FileCheck -check-prefix=NULL-VALID %s
 
-// CHECK: define void @foo(i32* nonnull %x)
+// NULL-INVALID: define void @foo(i32* nonnull %x)
+// NULL-VALID: define void @foo(i32* %x)
 void foo(int * __attribute__((nonnull)) x) {
   *x = 0;
 }
 
-// CHECK: define void @bar(i32* nonnull %x)
+// NULL-INVALID: define void @bar(i32* nonnull %x)
+// NULL-VALID: define void @bar(i32* %x)
 void bar(int * x) __attribute__((nonnull(1)))  {
   *x = 0;
 }
 
-// CHECK: define void @bar2(i32* %x, i32* nonnull %y)
+// NULL-INVALID: define void @bar2(i32* %x, i32* nonnull %y)
+// NULL-VALID: define void @bar2(i32* %x, i32* %y)
 void bar2(int * x, int * y) __attribute__((nonnull(2)))  {
   *x = 0;
 }
 
 static int a;
-// CHECK: define nonnull i32* @bar3()
+// NULL-INVALID: define nonnull i32* @bar3()
+// NULL-VALID: define i32* @bar3()
 int * bar3() __attribute__((returns_nonnull))  {
   return &a;
 }
 
-// CHECK: define i32 @bar4(i32 %n, i32* nonnull %p)
+// NULL-INVALID: define i32 @bar4(i32 %n, i32* nonnull %p)
+// NULL-VALID: define i32 @bar4(i32 %n, i32* %p)
 int bar4(int n, int *p) __attribute__((nonnull)) {
   return n + *p;
 }
 
-// CHECK: define i32 @bar5(i32 %n, i32* nonnull %p)
+// NULL-INVALID: define i32 @bar5(i32 %n, i32* nonnull %p)
+// NULL-VALID: define i32 @bar5(i32 %n, i32* %p)
 int bar5(int n, int *p) __attribute__((nonnull(1, 2))) {
   return n + *p;
 }
@@ -37,15 +44,18 @@ typedef union {
   double d;
 } TransparentUnion __attribute__((transparent_union));
 
-// CHECK: define i32 @bar6(i64 %
+// NULL-INVALID: define i32 @bar6(i64 %
+// NULL-VALID: define i32 @bar6(i64 %
 int bar6(TransparentUnion tu) __attribute__((nonnull(1))) {
   return *tu.p;
 }
 
-// CHECK: define void @bar7(i32* nonnull %a, i32* nonnull %b)
+// NULL-INVALID: define void @bar7(i32* nonnull %a, i32* nonnull %b)
+// NULL-VALID: define void @bar7(i32* %a, i32* %b)
 void bar7(int *a, int *b) __attribute__((nonnull(1)))
 __attribute__((nonnull(2))) {}
 
-// CHECK: define void @bar8(i32* nonnull %a, i32* nonnull %b)
+// NULL-INVALID: define void @bar8(i32* nonnull %a, i32* nonnull %b)
+// NULL-VALID: define void @bar8(i32* %a, i32* %b)
 void bar8(int *a, int *b) __attribute__((nonnull))
 __attribute__((nonnull(1))) {}

test/CodeGen/vla.c

@@ -1,4 +1,5 @@
-// RUN: %clang_cc1 -triple i386-unknown-unknown %s -emit-llvm -o - | FileCheck %s
+// RUN: %clang_cc1 -triple i386-unknown-unknown %s -emit-llvm -o - | FileCheck %s -check-prefixes=CHECK,NULL-INVALID
+// RUN: %clang_cc1 -triple i386-unknown-unknown %s -emit-llvm -fno-delete-null-pointer-checks -o - | FileCheck %s -check-prefixes=CHECK,NULL-VALID
 
 int b(char* x);
 
@@ -202,5 +203,6 @@ void test8(int a[static 3]) { }
 // CHECK: define void @test8(i32* dereferenceable(12) %a)
 
 void test9(int n, int a[static n]) { }
-// CHECK: define void @test9(i32 %n, i32* nonnull %a)
+// NULL-INVALID: define void @test9(i32 %n, i32* nonnull %a)
+// NULL-VALID: define void @test9(i32 %n, i32* %a)
 

test/CodeGenCXX/address-space-ref.cpp

@@ -1,4 +1,5 @@
-// RUN: %clang_cc1 %s -std=c++11 -triple=x86_64-apple-darwin10 -emit-llvm -o - | FileCheck %s
+// RUN: %clang_cc1 %s -std=c++11 -triple=x86_64-apple-darwin10 -emit-llvm -o - | FileCheck %s -check-prefixes=CHECK,NULL-INVALID
+// RUN: %clang_cc1 %s -std=c++11 -triple=x86_64-apple-darwin10 -fno-delete-null-pointer-checks -emit-llvm -o - | FileCheck %s -check-prefixes=CHECK,NULL-VALID
 
 // For a reference to a complete type, output the dereferenceable attribute (in
 // any address space).
@@ -29,6 +30,7 @@ bc & bar2(bc &x, bc & y) {
   return x;
 }
 
-// CHECK: define nonnull %class.bc* @_Z4bar2R2bcS0_(%class.bc* nonnull %x, %class.bc* nonnull %y)
+// NULL-INVALID: define nonnull %class.bc* @_Z4bar2R2bcS0_(%class.bc* nonnull %x, %class.bc* nonnull %y)
+// NULL-VALID: define %class.bc* @_Z4bar2R2bcS0_(%class.bc* %x, %class.bc* %y)
 
 

test/CodeGenCXX/constructors.cpp

@@ -1,4 +1,5 @@
-// RUN: %clang_cc1 -triple x86_64-apple-darwin10 %s -emit-llvm -o - | FileCheck %s --implicit-check-not=should_not_appear_in_output
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 %s -emit-llvm -o - | FileCheck %s --implicit-check-not=should_not_appear_in_output --check-prefixes=CHECK,NULL-INVALID
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 %s -emit-llvm -fno-delete-null-pointer-checks -o - | FileCheck %s --implicit-check-not=should_not_appear_in_output --check-prefixes=CHECK,NULL-VALID
 
 struct Member { int x; Member(); Member(int); Member(const Member &); };
 struct VBase { int x; VBase(); VBase(int); VBase(const VBase &); };
@@ -21,10 +22,12 @@ struct A {
 A::A(struct Undeclared &ref) : mem(0) {}
 
 // Check that delegation works.
-// CHECK-LABEL: define void @_ZN1AC2ER10Undeclared(%struct.A* %this, %struct.Undeclared* nonnull %ref) unnamed_addr
+// NULL-INVALID-LABEL: define void @_ZN1AC2ER10Undeclared(%struct.A* %this, %struct.Undeclared* nonnull %ref) unnamed_addr
+// NULL-VALID-LABEL: define void @_ZN1AC2ER10Undeclared(%struct.A* %this, %struct.Undeclared* %ref) unnamed_addr
 // CHECK: call void @_ZN6MemberC1Ei(
 
-// CHECK-LABEL: define void @_ZN1AC1ER10Undeclared(%struct.A* %this, %struct.Undeclared* nonnull %ref) unnamed_addr
+// NULL-INVALID-LABEL: define void @_ZN1AC1ER10Undeclared(%struct.A* %this, %struct.Undeclared* nonnull %ref) unnamed_addr
+// NULL-VALID-LABEL: define void @_ZN1AC1ER10Undeclared(%struct.A* %this, %struct.Undeclared* %ref) unnamed_addr
 // CHECK: call void @_ZN1AC2ER10Undeclared(
 
 A::A(ValueClass v) : mem(v.y - v.x) {}
@@ -43,11 +46,13 @@ struct B : A {
 
 B::B(struct Undeclared &ref) : A(ref), mem(1) {}
 
-// CHECK-LABEL: define void @_ZN1BC2ER10Undeclared(%struct.B* %this, %struct.Undeclared* nonnull %ref) unnamed_addr
+// NULL-INVALID-LABEL: define void @_ZN1BC2ER10Undeclared(%struct.B* %this, %struct.Undeclared* nonnull %ref) unnamed_addr
+// NULL-VALID-LABEL: define void @_ZN1BC2ER10Undeclared(%struct.B* %this, %struct.Undeclared* %ref) unnamed_addr
 // CHECK: call void @_ZN1AC2ER10Undeclared(
 // CHECK: call void @_ZN6MemberC1Ei(
 
-// CHECK-LABEL: define void @_ZN1BC1ER10Undeclared(%struct.B* %this, %struct.Undeclared* nonnull %ref) unnamed_addr
+// NULL-INVALID-LABEL: define void @_ZN1BC1ER10Undeclared(%struct.B* %this, %struct.Undeclared* nonnull %ref) unnamed_addr
+// NULL-VALID-LABEL: define void @_ZN1BC1ER10Undeclared(%struct.B* %this, %struct.Undeclared* %ref) unnamed_addr
 // CHECK: call void @_ZN1BC2ER10Undeclared(
 
 

test/CodeGenCXX/temporaries.cpp

@@ -1,4 +1,5 @@
-// RUN: %clang_cc1 -emit-llvm %s -o - -triple=x86_64-apple-darwin9 -std=c++11 | FileCheck %s
+// RUN: %clang_cc1 -emit-llvm %s -o - -triple=x86_64-apple-darwin9 -std=c++11 | FileCheck %s -check-prefixes=CHECK,NULL-INVALID
+// RUN: %clang_cc1 -emit-llvm %s -o - -triple=x86_64-apple-darwin9 -std=c++11 -fno-delete-null-pointer-checks | FileCheck %s -check-prefixes=CHECK,NULL-VALID
 
 namespace PR16263 {
   const unsigned int n = 1234;
@@ -333,7 +334,8 @@ namespace PR6648 {
   struct D;
   D& zed(B);
   void foobar() {
-    // CHECK: call nonnull %"struct.PR6648::D"* @_ZN6PR66483zedENS_1BE
+    // NULL-INVALID: call nonnull %"struct.PR6648::D"* @_ZN6PR66483zedENS_1BE
+    // NULL-VALID: call %"struct.PR6648::D"* @_ZN6PR66483zedENS_1BE
     zed(foo);
   }
 }

test/Driver/clang_f_opts.c

@@ -348,7 +348,6 @@
 // RUN: -fwhole-program                                                       \
 // RUN: -fcaller-saves                                                        \
 // RUN: -freorder-blocks                                                      \
-// RUN: -fdelete-null-pointer-checks                                          \
 // RUN: -ffat-lto-objects                                                     \
 // RUN: -fmerge-constants                                                     \
 // RUN: -finline-small-functions                                              \
@@ -414,7 +413,6 @@
 // CHECK-WARNING-DAG: optimization flag '-fwhole-program' is not supported
 // CHECK-WARNING-DAG: optimization flag '-fcaller-saves' is not supported
 // CHECK-WARNING-DAG: optimization flag '-freorder-blocks' is not supported
-// CHECK-WARNING-DAG: optimization flag '-fdelete-null-pointer-checks' is not supported
 // CHECK-WARNING-DAG: optimization flag '-ffat-lto-objects' is not supported
 // CHECK-WARNING-DAG: optimization flag '-fmerge-constants' is not supported
 // CHECK-WARNING-DAG: optimization flag '-finline-small-functions' is not supported
@@ -526,3 +524,10 @@
 // RUN: %clang -### -S -fno-merge-all-constants -fmerge-all-constants %s 2>&1 | FileCheck -check-prefix=CHECK-MERGE-ALL-CONSTANTS %s
 // CHECK-NO-MERGE-ALL-CONSTANTS-NOT: "-fmerge-all-constants"
 // CHECK-MERGE-ALL-CONSTANTS: "-fmerge-all-constants"
+
+// RUN: %clang -### -S -fdelete-null-pointer-checks %s 2>&1 | FileCheck -check-prefix=CHECK-NULL-POINTER-CHECKS %s
+// RUN: %clang -### -S -fno-delete-null-pointer-checks %s 2>&1 | FileCheck -check-prefix=CHECK-NO-NULL-POINTER-CHECKS %s
+// RUN: %clang -### -S -fdelete-null-pointer-checks -fno-delete-null-pointer-checks %s 2>&1 | FileCheck -check-prefix=CHECK-NO-NULL-POINTER-CHECKS %s
+// RUN: %clang -### -S -fno-delete-null-pointer-checks -fdelete-null-pointer-checks %s 2>&1 | FileCheck -check-prefix=CHECK-NULL-POINTER-CHECKS %s
+// CHECK-NO-NULL-POINTER-CHECKS: "-fno-delete-null-pointer-checks"
+// CHECK-NULL-POINTER-CHECKS-NOT: "-fno-delete-null-pointer-checks"

test/Sema/nonnull.c

@@ -1,5 +1,9 @@
 // RUN: %clang_cc1 -fsyntax-only -verify %s
 // rdar://9584012
+//
+// Verify All warnings are still issued with the option -fno-delete-null-pointer-checks
+// if nullptr is passed to function with nonnull attribute.
+// RUN: %clang_cc1 -fsyntax-only -fno-delete-null-pointer-checks -verify %s
 
 typedef struct {
 	char *str;