Index: include/clang/Basic/Attr.td =================================================================== --- include/clang/Basic/Attr.td +++ include/clang/Basic/Attr.td @@ -1495,6 +1495,12 @@ let Documentation = [NotTailCalledDocs]; } +def NoStackProtector : InheritableAttr { + let Spellings = [Clang<"no_stack_protector">]; + let Subjects = SubjectList<[Function]>; + let Documentation = [NoStackProtectorDocs]; +} + def NoThrow : InheritableAttr { let Spellings = [GCC<"nothrow">, Declspec<"nothrow">]; let Subjects = SubjectList<[Function]>; Index: include/clang/Basic/AttrDocs.td =================================================================== --- include/clang/Basic/AttrDocs.td +++ include/clang/Basic/AttrDocs.td @@ -2740,6 +2740,28 @@ }]; } +def NoStackProtectorDocs : Documentation { + let Category = DocCatFunction; + let Content = [{ +Clang supports the ``__attribute__((no_stack_protector))`` attribute which disables +the stack protector on the specified function. This attribute is useful for +selectively disabling the stack protector on some functions when building with +``-fstack-protector`` compiler option. + +For example, it disables the stack protector for the function ``foo`` but function +``bar`` will still be built with the stack protector with the ``-fstack-protector`` +option. + +.. code-block:: c + + int __attribute__((no_stack_protector)) + foo (int x); // stack protection will be disabled for foo. + + int bar(int y); // bar can be built with the stack protector. + + }]; +} + def NotTailCalledDocs : Documentation { let Category = DocCatFunction; let Content = [{ Index: lib/CodeGen/CodeGenModule.cpp =================================================================== --- lib/CodeGen/CodeGenModule.cpp +++ lib/CodeGen/CodeGenModule.cpp @@ -1142,12 +1142,14 @@ if (!hasUnwindExceptions(LangOpts)) B.addAttribute(llvm::Attribute::NoUnwind); - if (LangOpts.getStackProtector() == LangOptions::SSPOn) - B.addAttribute(llvm::Attribute::StackProtect); - else if (LangOpts.getStackProtector() == LangOptions::SSPStrong) - B.addAttribute(llvm::Attribute::StackProtectStrong); - else if (LangOpts.getStackProtector() == LangOptions::SSPReq) - B.addAttribute(llvm::Attribute::StackProtectReq); + if (!D || !D->hasAttr()) { + if (LangOpts.getStackProtector() == LangOptions::SSPOn) + B.addAttribute(llvm::Attribute::StackProtect); + else if (LangOpts.getStackProtector() == LangOptions::SSPStrong) + B.addAttribute(llvm::Attribute::StackProtectStrong); + else if (LangOpts.getStackProtector() == LangOptions::SSPReq) + B.addAttribute(llvm::Attribute::StackProtectReq); + } if (!D) { // If we don't have a declaration to control inlining, the function isn't Index: lib/Sema/SemaDeclAttr.cpp =================================================================== --- lib/Sema/SemaDeclAttr.cpp +++ lib/Sema/SemaDeclAttr.cpp @@ -6230,6 +6230,10 @@ case AttributeList::AT_NoInstrumentFunction: // Interacts with -pg. handleSimpleAttribute(S, D, AL); break; + case AttributeList::AT_NoStackProtector: + // Interacts with -fstack-protector options. + handleSimpleAttribute(S, D, AL); + break; case AttributeList::AT_StdCall: case AttributeList::AT_CDecl: case AttributeList::AT_FastCall: Index: test/CodeGen/stack-protector.c =================================================================== --- test/CodeGen/stack-protector.c +++ test/CodeGen/stack-protector.c @@ -22,6 +22,14 @@ printf("%s\n", a); } +// DEF: define {{.*}}void @test2(i8* %msg) #[[B:.*]] { +__attribute__((no_stack_protector)) +void test2(const char *msg) { + char a[strlen(msg) + 1]; + strcpy(a, msg); + printf("%s\n", a); +} + // NOSSP-NOT: attributes #[[A]] = {{.*}} ssp // SSP: attributes #[[A]] = {{.*}} ssp{{ }} // SSPSTRONG: attributes #[[A]] = {{.*}} sspstrong @@ -33,3 +41,15 @@ // SAFESTACK-SSP: attributes #[[A]] = {{.*}} safestack ssp{{ }} // SAFESTACK-SSPSTRONG: attributes #[[A]] = {{.*}} safestack sspstrong // SAFESTACK-SSPREQ: attributes #[[A]] = {{.*}} safestack sspreq + +// NOSSP-NOT: attributes #[[B]] = {{.*}} ssp +// SSP-NOT: attributes #[[B]] = {{.*}} ssp{{ }} +// SSPSTRONG-NOT: attributes #[[B]] = {{.*}} sspstrong +// SSPREQ-NOT: attributes #[[B]] = {{.*}} sspreq + +// SAFESTACK-SSP: attributes #[[B]] = {{.*}} safestack +// SAFESTACK-SSP-NOT: attributes #[[B]] = {{.*}} safestack ssp{{ }} +// SAFESTACK-SSPSTRONG: attributes #[[B]] = {{.*}} safestack +// SAFESTACK-SSPSTRONG-NOT: attributes #[[B]] = {{.*}} safestack sspstrong +// SAFESTACK-SSPREQ: attributes #[[B]] = {{.*}} safestack +// SAFESTACK-SSPREQ-NOT: attributes #[[B]] = {{.*}} safestack sspreq Index: test/Sema/no_stack_protector.c =================================================================== --- test/Sema/no_stack_protector.c +++ test/Sema/no_stack_protector.c @@ -0,0 +1,5 @@ +// RUN: %clang_cc1 -fsyntax-only -verify %s + +void __attribute__((no_stack_protector)) foo() {} +int __attribute__((no_stack_protector)) var; // expected-warning {{'no_stack_protector' attribute only applies to functions}} +void __attribute__((no_stack_protector(2))) bar() {} // expected-error {{'no_stack_protector' attribute takes no arguments}}