[ubsan] Enable -fsanitize=vptr on Apple devices and simulators

[vsk]

Summary

It seems like an oversight that this check was not always enabled for
on-device or device simulator targets.

[delcypher]

clang/lib/Driver/ToolChains/Darwin.cpp

2254 ↗

(On Diff #162493)

Could we apply De'Morgan's rule here and write that as

if (!(isTargetMacOS() && isMacosxVersionLT(10, 9)) {
  Res |= SanitizerKind::Vptr
}

I find that a bit easier to read.

Is there any particular reason why vptr isn't supported for old macOS versions? There's no mention of ios here which suggests that it's supported on all ios versions which seems like an odd disparity. Perhaps a comment briefly explaining why this is the case would be helpful?

[vsk]

clang/lib/Driver/ToolChains/Darwin.cpp

2254 ↗

(On Diff #162493)

Sure.

MacOS versions older than 10.8 shipped a version of the C++ standard library which is incompatible with the vptr check's implementation (see: https://trac.macports.org/wiki/LibcxxOnOlderSystems). I'll add a comment to that effect.

As far as I know, all currently-supported versions of iOS ship libc++. I'll ask around and double-check, just to be safe.

[vsk]

Address some review feedback.

I'm not sure whether iOS 4 is really supported anymore. There are a handful of code paths in the driver which handle that target, so I've added in a version check for it.

[delcypher]

LGTM.

clang/test/Driver/fsanitize.c

426 ↗

(On Diff #162732)

@vsk Interesting. This that what the iOS 4 target triple looked like.

cfe/trunk/lib/Driver/ToolChains/Darwin.cpp

 SanitizerMask Darwin::getSupportedSanitizers() const {
   const bool IsX86_64 = getTriple().getArch() == llvm::Triple::x86_64;
   SanitizerMask Res = ToolChain::getSupportedSanitizers();
   Res |= SanitizerKind::Address;
   Res |= SanitizerKind::Leak;
   Res |= SanitizerKind::Fuzzer;
   Res |= SanitizerKind::FuzzerNoLink;
   Res |= SanitizerKind::Function;
-  if (isTargetMacOS()) {
-    if (!isMacosxVersionLT(10, 9))
-      Res |= SanitizerKind::Vptr;
+
+  // Prior to 10.9, macOS shipped a version of the C++ standard library without
+  // C++11 support. The same is true of iOS prior to version 5. These OS'es are
+  // incompatible with -fsanitize=vptr.
+  if (!(isTargetMacOS() && isMacosxVersionLT(10, 9))
+      && !(isTargetIPhoneOS() && isIPhoneOSVersionLT(5, 0)))
+
+  if (isTargetMacOS()) {
     if (IsX86_64)
       Res |= SanitizerKind::Thread;
   } else if (isTargetIOSSimulator() || isTargetTvOSSimulator()) {
     if (IsX86_64)
       Res |= SanitizerKind::Thread;
   }
   return Res;
 }
 
 void Darwin::printVerboseInfo(raw_ostream &OS) const {
   CudaInstallation.print(OS);
 }

cfe/trunk/test/Driver/fsanitize.c

 
 // RUN: %clang -target x86_64-apple-darwin10 -fsanitize=function %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-FSAN-DARWIN
 // RUN: %clang -target i386-apple-darwin10 -fsanitize=function %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-FSAN-DARWIN
 // CHECK-FSAN-DARWIN: -cc1{{.*}}"-fsanitize=function" "-fsanitize-recover=function"
 
 // RUN: %clang -target x86_64-apple-darwin10 -mmacosx-version-min=10.8 -fsanitize=vptr %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-VPTR-DARWIN-OLD
 // CHECK-VPTR-DARWIN-OLD: unsupported option '-fsanitize=vptr' for target 'x86_64-apple-darwin10'
 
+// RUN: %clang -target arm-apple-ios4 -fsanitize=vptr %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-VPTR-IOS-OLD
+// CHECK-VPTR-IOS-OLD: unsupported option '-fsanitize=vptr' for target 'arm-apple-ios4'
+
+// RUN: %clang -target aarch64-apple-darwin15.0.0 -fsanitize=vptr %s -### 2>&1
+// OK
+
+// RUN: %clang -target x86_64-apple-darwin15.0.0-simulator -fsanitize=vptr %s -### 2>&1
+// OK
+
 // RUN: %clang -target x86_64-apple-darwin10 -mmacosx-version-min=10.9 -fsanitize=alignment,vptr %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-VPTR-DARWIN-NEW
 // CHECK-VPTR-DARWIN-NEW: -fsanitize=alignment,vptr
 
 // RUN: %clang -target armv7-apple-ios7 -miphoneos-version-min=7.0 -fsanitize=address %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-ASAN-IOS
 // CHECK-ASAN-IOS: -fsanitize=address
 
 // RUN %clang -target i386-pc-openbsd -fsanitize=undefined %s -### 2>&1 | FileCheck --check-prefix=CHECK-UBSAN-OPENBSD
 // CHECK-UBSAN-OPENBSD: -fsanitize=undefined