Implement diagnostic mode for -fsanitize=cfi*, -fsanitize=cfi-diag.

This causes programs compiled with this flag to print a diagnostic when
a control flow integrity check fails instead of aborting. Diagnostics are
printed using UBSan's runtime library.

The main motivation of this feature over -fsanitize=vptr is fidelity with
the -fsanitize=cfi implementation: the diagnostics are printed under exactly
the same conditions as those which would cause -fsanitize=cfi to abort the
program. This means that the same restrictions apply regarding compiling
all translation units with -fsanitize=cfi, cross-DSO virtual calls are
forbidden, etc.

Differential Revision: http://reviews.llvm.org/D10268

llvm-svn: 240109

1 files changed, 6 insertions, 2 deletions

diff --git a/clang/lib/Driver/SanitizerArgs.cpp b/clang/lib/Driver/SanitizerArgs.cpp
index fee6e8f3ed3..9918fcbd5e1 100644
--- a/clang/lib/Driver/SanitizerArgs.cpp
+++ b/clang/lib/Driver/SanitizerArgs.cpp
@@ -25,7 +25,7 @@ using namespace clang::driver;
 using namespace llvm::opt;
 
 enum : SanitizerMask {
-  NeedsUbsanRt = Undefined | Integer,
+  NeedsUbsanRt = Undefined | Integer | CFI,
   NotAllowedWithTrap = Vptr,
   RequiresPIE = Memory | DataFlow,
   NeedsUnwindTables = Address | Thread | Memory | DataFlow,
@@ -35,7 +35,8 @@ enum : SanitizerMask {
   LegacyFsanitizeRecoverMask = Undefined | Integer,
   NeedsLTO = CFI,
   TrappingSupported =
-      (Undefined & ~Vptr) | UnsignedIntegerOverflow | LocalBounds,
+      (Undefined & ~Vptr) | UnsignedIntegerOverflow | LocalBounds | CFI,
+  TrappingDefault = CFI,
 };
 
 enum CoverageFeature {
@@ -166,6 +167,9 @@ static SanitizerMask parseSanitizeTrapArgs(const Driver &D,
     }
   }
 
+  // Apply default trapping behavior.
+  TrappingKinds |= TrappingDefault & ~TrapRemove;
+
   return TrappingKinds;
 }