Remove branch after control point.

Since deoptimisation now doesn't require us to return to the control point
anymore, we can remove the control points return type and the branch with the
call to the frame reconstruction code.

Author: ptersilie

llvm/lib/Transforms/Yk/ControlPoint.cpp

@@ -162,11 +162,11 @@ class YkControlPoint : public ModulePass {
             ->getType();
 
     // Create the new control point, which is of the form:
-    //   void* new_control_point(YkMT*, YkLocation*, CtrlPointVars*, void*)
+    //   void new_control_point(YkMT*, YkLocation*, CtrlPointVars*, void*)
     PointerType *VoidPtr = PointerType::get(Context, 0);
     FunctionType *FType = FunctionType::get(
-        VoidPtr, {YkMTTy, YkLocTy, CtrlPointVarsTy->getPointerTo(), VoidPtr},
-        false);
+        Type::getVoidTy(Context),
+        {YkMTTy, YkLocTy, CtrlPointVarsTy->getPointerTo(), VoidPtr}, false);
     Function *NF = Function::Create(FType, GlobalVariable::ExternalLinkage,
                                     YK_NEW_CONTROL_POINT, M);
 
@@ -219,35 +219,6 @@ class YkControlPoint : public ModulePass {
     // Replace the call to the dummy control point.
     OldCtrlPointCall->eraseFromParent();
 
-    // Create the new exit block.
-    BasicBlock *ExitBB = BasicBlock::Create(Context, "", Caller);
-    Builder.SetInsertPoint(ExitBB);
-
-    // Create call to frame reconstructor.
-    FunctionType *YKFRType =
-        FunctionType::get(Type::getVoidTy(Context), {VoidPtr}, false);
-    Function *YKFR = Function::Create(YKFRType, GlobalVariable::ExternalLinkage,
-                                      YK_RECONSTRUCT_FRAMES, M);
-    Builder.CreateCall(YKFR, {NewCtrlPointCallInst});
-    Builder.CreateUnreachable();
-
-    // Split up the current block and then insert a conditional branch that
-    // either continues after the control point or invokes frame reconstruction.
-    BasicBlock *BB = NewCtrlPointCallInst->getParent();
-    BasicBlock *ContBB = BB->splitBasicBlock(New->getNextNonDebugInstruction());
-    Instruction &OldBr = BB->back();
-    assert(OldBr.getPrevNonDebugInstruction() == New &&
-           "Split block at the wrong spot.");
-    OldBr.eraseFromParent();
-    Builder.SetInsertPoint(BB);
-    // The return value of the control point tells us whether a guard has failed
-    // or not (i.e. anything other than a nullptr means a guard has failed). If
-    // it has jump to `ExitBB` which calls the code that copies over the new
-    // stack from the given pointer.
-    Value *HasGuardFailed = Builder.CreateICmpEQ(
-        NewCtrlPointCallInst, ConstantPointerNull::get(VoidPtr));
-    Builder.CreateCondBr(HasGuardFailed, ContBB, ExitBB);
-
 #ifndef NDEBUG
     // Our pass runs after LLVM normally does its verify pass. In debug builds
     // we run it again to check that our pass is generating valid IR.