[PATCH] D119816: [SanitizerBounds] Add support for NoSanitizeBounds function

[Tong Zhang via Phabricator via llvm-commits]

ztong0001 added inline comments.


================
Comment at: clang/lib/CodeGen/CodeGenFunction.cpp:757
         SanOpts.set(SanitizerKind::HWAddress, false);
+      if (mask & SanitizerKind::LocalBounds)
+        Fn->addFnAttr(llvm::Attribute::NoSanitizeBounds);
----------------
ztong0001 wrote:
> melver wrote:
> > These 2 checks can be reduced to 1 due to SanitizerKind::Bounds including both. However, as noted, this only affects local-bounds, so I'm not sure if we want to include both -- perhaps for completeness it makes sense, but in the array-bounds only case this attribute will be a nop (AFAIK).
> > 
> > Also, I think we don't want to attach the attribute if bounds checking isn't enabled -- at least it seems unnecessary to do so.
> > 
> > See the following suggested change:
> > 
> > ```
> > diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp
> > index 842ce0245d45..c1f3a3014a19 100644
> > --- a/clang/lib/CodeGen/CodeGenFunction.cpp
> > +++ b/clang/lib/CodeGen/CodeGenFunction.cpp
> > @@ -740,6 +740,7 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
> >    } while (false);
> >  
> >    if (D) {
> > +    const bool SanitizeBounds = SanOpts.hasOneOf(SanitizerKind::Bounds);
> >      bool NoSanitizeCoverage = false;
> >  
> >      for (auto Attr : D->specific_attrs<NoSanitizeAttr>()) {
> > @@ -754,16 +755,15 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
> >          SanOpts.set(SanitizerKind::KernelHWAddress, false);
> >        if (mask & SanitizerKind::KernelHWAddress)
> >          SanOpts.set(SanitizerKind::HWAddress, false);
> > -      if (mask & SanitizerKind::LocalBounds)
> > -        Fn->addFnAttr(llvm::Attribute::NoSanitizeBounds);
> > -      if (mask & SanitizerKind::ArrayBounds)
> > -        Fn->addFnAttr(llvm::Attribute::NoSanitizeBounds);
> >  
> >        // SanitizeCoverage is not handled by SanOpts.
> >        if (Attr->hasCoverage())
> >          NoSanitizeCoverage = true;
> >      }
> >  
> > +    if (SanitizeBounds && !SanOpts.hasOneOf(SanitizerKind::Bounds))
> > +      Fn->addFnAttr(llvm::Attribute::NoSanitizeBounds);
> > +
> >      if (NoSanitizeCoverage && CGM.getCodeGenOpts().hasSanitizeCoverage())
> >        Fn->addFnAttr(llvm::Attribute::NoSanitizeCoverage);
> >    }
> > 
> > ```
> Agreed. I will revise patch and commit description.
BTW: Just to double check we are on the same page

when no_sanitize(bounds) is provided, fsanitize=array-bounds is also disabled -- right ? I can confirm this attribute is also affecting array-bounds as this is handled in clang side and we are setting llvm::Attribute::NoSanitizeBounds so that clang's array-bounds can also see this.

I will also add another test for -fsanitize=array-bounds


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D119816/new/

https://reviews.llvm.org/D119816