[PATCH] D41880: Adding nocf_check attribute for cf-protection fine tuning

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman added inline comments.


================
Comment at: lib/Sema/SemaDeclAttr.cpp:1990
 
-bool Sema::CheckNoReturnAttr(const AttributeList &Attrs) {
-  if (!checkAttributeNumArgs(*this, Attrs, 0)) {
-    Attrs.setInvalid();
+static void handleNoCfCheckAttr(Sema &S, Decl *D, const AttributeList &attr) {
+  if (S.CheckAttrTarget(attr) || S.CheckAttrNoArgs(attr))
----------------
oren_ben_simhon wrote:
> aaron.ballman wrote:
> > oren_ben_simhon wrote:
> > > aaron.ballman wrote:
> > > > aaron.ballman wrote:
> > > > > `attr` doesn't follow the proper naming conventions.
> > > > Please don't name the parameter variable after a type -- that can confuse some editors.
> > > I am following the same convention that other functions are using.
> > > I am following the same convention that other functions are using.
> > 
> > They're doing it wrong. I can clean those up in a separate patch.
> Its OK i can make the change.
I've commit a cleanup in r325256 that fixes the identifiers in the file (along with several other coding standard issues).


================
Comment at: test/Sema/attr-nocf_check.c:18-20
+  FuncPointerWithNoCfCheck fNoCfCheck = f; // no-warning
+  (*fNoCfCheck)();                       // no-warning
+  f = fNoCfCheck;                        // no-warning
----------------
oren_ben_simhon wrote:
> aaron.ballman wrote:
> > oren_ben_simhon wrote:
> > > aaron.ballman wrote:
> > > > These are an error in GCC and I think we should match that behavior. https://godbolt.org/g/r3pf4X
> > > I will create a warning however in LLVM we don't create an error upon incompatible pointer due to function attribute types.
> > It should be an error -- Clang does error on this sort of thing when appropriate (which I believe it is, here). For instance, calling convention attributes do this: https://godbolt.org/g/mkTGLg
> In Clang there is Sema::IncompatiblePointer in case to pointers are not compatible. This flag emits warning message. In the time i check for pointer incompatibility (checkPointerTypesForAssignment()), i don;t have a handle to the attributes. Any suggestion how to implement the exception for nocf_check attribute?
I believe this is handled in `ASTContext::mergeFunctionType()`. See:
```
  // Compatible functions must have compatible calling conventions
  if (lbaseInfo.getCC() != rbaseInfo.getCC())
    return QualType();
```
Somewhere around there is likely where you should be.


Repository:
  rL LLVM

https://reviews.llvm.org/D41880