Driver: Objective-C should respect -fno-exceptions

Clang attempted to replicate a GCC bug: -fobjc-exceptions forces
-fexceptions to be enabled.  However, this has unintended effects and
other awkard side effects that Clang doesn't "correctly" ape (e.g. it's
impossible to turn off C++ exceptions in ObjC++ mode).

Instead, -f[no]objc-exceptions and -f[no]cxx-exceptions now have an
identical relationship with -f[no]exceptions.

llvm-svn: 223455

1 files changed, 14 insertions, 25 deletions

diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index 151d87b50de..9924bb8896d 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -1894,23 +1894,6 @@ static void getTargetFeatures(const Driver &D, const llvm::Triple &Triple,
   }
 }
 
-static bool
-shouldUseExceptionTablesForObjCExceptions(const ObjCRuntime &runtime,
-                                          const llvm::Triple &Triple) {
-  // We use the zero-cost exception tables for Objective-C if the non-fragile
-  // ABI is enabled or when compiling for x86_64 and ARM on Snow Leopard and
-  // later.
-  if (runtime.isNonFragile())
-    return true;
-
-  if (!Triple.isMacOSX())
-    return false;
-
-  return (!Triple.isMacOSXVersionLT(10,5) &&
-          (Triple.getArch() == llvm::Triple::x86_64 ||
-           Triple.getArch() == llvm::Triple::arm));
-}
-
 // exceptionSettings() exists to share the logic between -cc1 and linker
 // invocations.
 static bool exceptionSettings(const ArgList &Args, const llvm::Triple &Triple) {
@@ -1947,15 +1930,21 @@ static void addExceptionArgs(const ArgList &Args, types::ID InputType,
   // Gather the exception settings from the command line arguments.
   bool EH = exceptionSettings(Args, Triple);
 
-  // Obj-C exceptions are enabled by default, regardless of -fexceptions. This
-  // is not necessarily sensible, but follows GCC.
-  if (types::isObjC(InputType) &&
-      Args.hasFlag(options::OPT_fobjc_exceptions,
-                   options::OPT_fno_objc_exceptions,
-                   true)) {
-    CmdArgs.push_back("-fobjc-exceptions");
+  if (types::isObjC(InputType)) {
+    bool ObjCExceptionsEnabled = true;
+    if (Arg *A = Args.getLastArg(options::OPT_fobjc_exceptions,
+                                 options::OPT_fno_objc_exceptions,
+                                 options::OPT_fexceptions,
+                                 options::OPT_fno_exceptions))
+      ObjCExceptionsEnabled =
+          A->getOption().matches(options::OPT_fobjc_exceptions) ||
+          A->getOption().matches(options::OPT_fexceptions);
 
-    EH |= shouldUseExceptionTablesForObjCExceptions(objcRuntime, Triple);
+    if (ObjCExceptionsEnabled) {
+      CmdArgs.push_back("-fobjc-exceptions");
+
+      EH = true;
+    }
   }
 
   if (types::isCXX(InputType)) {