[MS ABI] Don't rely on terminatepad

[majnemer]

Summary

We'd like to remove support for terminatepad from LLVM. To do this, we
need to move Clang off of it first. The intent behind terminatepad was
to carefully model exception specifications for the MSVC personality.

However, we don't support exception specifications for the MSVC
personality and neither does MSVC. Instead, MSVC supports
all-or-nothing exception specifications. We can model this limited
usage using cleanuppads which call std::terminate.

[rnk]

lgtm

cfe/trunk/lib/CodeGen/CGException.cpp

if (TerminateHandler)
     return TerminateHandler;
 
   CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
 
   // Set up the terminate handler.  This block is inserted at the very
   // end of the function by FinishFunction.
   TerminateHandler = createBasicBlock("terminate.handler");
   Builder.SetInsertPoint(TerminateHandler);
+  llvm::Value *Exn = nullptr;
   if (EHPersonality::get(*this).usesFuncletPads()) {
     llvm::Value *ParentPad = CurrentFuncletPad;
     if (!ParentPad)
       ParentPad = llvm::ConstantTokenNone::get(CGM.getLLVMContext());
-    Builder.CreateTerminatePad(ParentPad, /*UnwindBB=*/nullptr,
-                               {CGM.getTerminateFn()});
+    Builder.CreateCleanupPad(ParentPad);
   } else {
-    llvm::Value *Exn = nullptr;
     if (getLangOpts().CPlusPlus)
       Exn = getExceptionFromSlot();
-    llvm::CallInst *terminateCall =
-        CGM.getCXXABI().emitTerminateForUnexpectedException(*this, Exn);
-    terminateCall->setDoesNotReturn();
-    Builder.CreateUnreachable();
-  }
+  }
 
   // Restore the saved insertion state.
   Builder.restoreIP(SavedIP);
 
   return TerminateHandler;
 }
 
 llvm::BasicBlock *CodeGenFunction::getEHResumeBlock(bool isCleanup) {

cfe/trunk/test/CodeGenCXX/exceptions-cxx-new.cpp

 // CHECK-LABEL: define {{.*}} void @"\01??1Cleanup@@QAE@XZ"(
 // CHECK:   invoke i32 @"\01?f@@YAHH@Z"(i32 -1)
 // CHECK:           to label %[[LEAVE_FUNC:.*]] unwind label %[[TERMINATE:.*]]
 
 // CHECK: [[LEAVE_FUNC]]
 // CHECK:   ret void
 
 // CHECK: [[TERMINATE]]
-// CHECK:   terminatepad within none [void ()* @"\01?terminate@@YAXXZ"] unwind to caller
+// CHECK:   cleanuppad within none []
+// CHECK-NEXT:   call void @"\01?terminate@@YAXXZ"()
 

cfe/trunk/test/CodeGenCXX/microsoft-abi-eh-terminate.cpp

 // RUN: %clang_cc1 -std=c++11 -emit-llvm %s -o - -triple=x86_64-pc-windows-msvc -mconstructor-aliases -fexceptions -fcxx-exceptions -fms-compatibility-version=18.00 | FileCheck -check-prefix=MSVC2013 %s
 // RUN: %clang_cc1 -std=c++11 -emit-llvm %s -o - -triple=x86_64-pc-windows-msvc -mconstructor-aliases -fexceptions -fcxx-exceptions -fms-compatibility-version=19.00 | FileCheck -check-prefix=MSVC2015 %s
 
 void may_throw();
 void never_throws() noexcept(true) {
   may_throw();
 }
 
 // CHECK-LABEL: define void @"\01?never_throws@@YAXXZ"()
 // CHECK-SAME:          personality i8* bitcast (i32 (...)* @__CxxFrameHandler3 to i8*)
 // CHECK:      invoke void @"\01?may_throw@@YAXXZ"()
-// MSVC2013:      terminatepad within none [void ()* @"\01?terminate@@YAXXZ"]
-// MSVC2015:      terminatepad within none [void ()* @__std_terminate]
+// CHECK:      cleanuppad within none []
+// MSVC2013:      call void @"\01?terminate@@YAXXZ"()
+// MSVC2015:      call void @__std_terminate()
 // CHECK-NEXT: unreachable