Have the SjLjEHPrepare pass do some more heavy lifting.

Upon further review, most of the EH code should remain written at the IR
level. The part which breaks SSA form is the dispatch table, so that part will
be moved to the back-end.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@140730 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/SjLjEHPrepare.cpp

@@ -58,6 +58,7 @@ namespace {
     Constant *ExceptionFn;
     Constant *CallSiteFn;
     Constant *DispatchSetupFn;
+    Constant *FuncCtxFn;
     Value *CallSite;
     DenseMap<InvokeInst*, BasicBlock*> LPadSuccMap;
   public:
@@ -74,7 +75,8 @@ namespace {
 
   private:
     bool setupEntryBlockAndCallSites(Function &F);
-    void setupFunctionContext(Function &F, ArrayRef<LandingPadInst*> LPads);
+    std::pair<Value*, Value*>
+    setupFunctionContext(Function &F, ArrayRef<LandingPadInst*> LPads);
 
     void insertCallSiteStore(Instruction *I, int Number, Value *CallSite);
     void markInvokeCallSite(InvokeInst *II, int InvokeNo, Value *CallSite,
@@ -125,6 +127,7 @@ bool SjLjEHPass::doInitialization(Module &M) {
   CallSiteFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_callsite);
   DispatchSetupFn
     = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_dispatch_setup);
+  FuncCtxFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_functioncontext);
   PersonalityFn = 0;
 
   return true;
@@ -709,8 +712,8 @@ bool SjLjEHPass::insertSjLjEHSupport(Function &F) {
 
 /// setupFunctionContext - Allocate the function context on the stack and fill
 /// it with all of the data that we know at this point.
-void SjLjEHPass::setupFunctionContext(Function &F,
+std::pair<Value*, Value*> SjLjEHPass::
-                                      ArrayRef<LandingPadInst*> LPads) {
+setupFunctionContext(Function &F, ArrayRef<LandingPadInst*> LPads) {
   BasicBlock *EntryBB = F.begin();
 
   // Create an alloca for the incoming jump buffer ptr and the new jump buffer
@@ -721,15 +724,6 @@ void SjLjEHPass::setupFunctionContext(Function &F,
   AllocaInst *FuncCtx =
     new AllocaInst(FunctionContextTy, 0, Align, "fn_context", EntryBB->begin());
 
-  // Store a pointer to the function context so that the back-end will know
-  // where to look for it.
-  CallInst::Create(Intrinsic::getDeclaration(F.getParent(),
-                                            Intrinsic::eh_sjlj_functioncontext),
-                   CastInst::Create(Instruction::BitCast, FuncCtx,
-                                    Type::getInt8PtrTy(F.getContext()), "",
-                                    EntryBB->getTerminator()),
-                   "", EntryBB->getTerminator());
-
   // Fill in the function context structure.
   Value *Idxs[2];
   Type *Int32Ty = Type::getInt32Ty(F.getContext());
@@ -811,18 +805,46 @@ void SjLjEHPass::setupFunctionContext(Function &F,
                                 EntryBB->getTerminator());
   new StoreInst(Val, FramePtr, true, EntryBB->getTerminator());
 
+  return std::make_pair(FuncCtx, JBufPtr);
+}
+
+/// setupEntryBlockAndCallSites - Setup the entry block by creating and filling
+/// the function context and marking the call sites with the appropriate
+/// values. These values are used by the DWARF EH emitter.
+bool SjLjEHPass::setupEntryBlockAndCallSites(Function &F) {
+  SmallVector<ReturnInst*,     16> Returns;
+  SmallVector<InvokeInst*,     16> Invokes;
+  SmallVector<LandingPadInst*, 16> LPads;
+
+  // Look through the terminators of the basic blocks to find invokes.
+  for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
+    if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
+      Invokes.push_back(II);
+      LPads.push_back(II->getUnwindDest()->getLandingPadInst());
+    } else if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
+      Returns.push_back(RI);
+    }
+
+  if (Invokes.empty()) return false;
+
+  std::pair<Value*, Value*> FuncCtx = setupFunctionContext(F, LPads);
+  BasicBlock *EntryBB = F.begin();
+
   // Save the stack pointer.
-  Idxs[1] = ConstantInt::get(Int32Ty, 2);
+  Type *Int32Ty = Type::getInt32Ty(F.getContext());
+  Value *Idxs[2] = {
+    ConstantInt::get(Int32Ty, 0), ConstantInt::get(Int32Ty, 2)
+  };
   Value *StackPtr =
-    GetElementPtrInst::Create(JBufPtr, Idxs, "jbuf_sp_gep",
+    GetElementPtrInst::Create(FuncCtx.second, Idxs, "jbuf_sp_gep",
                               EntryBB->getTerminator());
 
-  Val = CallInst::Create(StackAddrFn, "sp", EntryBB->getTerminator());
+  Value *Val = CallInst::Create(StackAddrFn, "sp", EntryBB->getTerminator());
   new StoreInst(Val, StackPtr, true, EntryBB->getTerminator());
 
   // Call the setjmp instrinsic. It fills in the rest of the jmpbuf.
   Value *SetjmpArg =
-    CastInst::Create(Instruction::BitCast, JBufPtr,
+    CastInst::Create(Instruction::BitCast, FuncCtx.second,
                      Type::getInt8PtrTy(F.getContext()), "",
                      EntryBB->getTerminator());
   Value *DispatchVal = CallInst::Create(BuiltinSetjmpFn, SetjmpArg,
@@ -832,25 +854,14 @@ void SjLjEHPass::setupFunctionContext(Function &F,
   // Add a call to dispatch_setup after the setjmp call. This is expanded to any
   // target-specific setup that needs to be done.
   CallInst::Create(DispatchSetupFn, DispatchVal, "", EntryBB->getTerminator());
-}
 
-/// setupEntryBlockAndCallSites - Setup the entry block by creating and filling
+  // Store a pointer to the function context so that the back-end will know
-/// the function context and marking the call sites with the appropriate
+  // where to look for it.
-/// values. These values are used by the DWARF EH emitter.
+  Value *FuncCtxArg =
-bool SjLjEHPass::setupEntryBlockAndCallSites(Function &F) {
+    CastInst::Create(Instruction::BitCast, FuncCtx.first,
-  SmallVector<InvokeInst*,     16> Invokes;
+                     Type::getInt8PtrTy(F.getContext()), "",
-  SmallVector<LandingPadInst*, 16> LPads;
+                     EntryBB->getTerminator());
-
+  CallInst::Create(FuncCtxFn, FuncCtxArg, "", EntryBB->getTerminator());
-  // Look through the terminators of the basic blocks to find invokes.
-  for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
-    if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
-      Invokes.push_back(II);
-      LPads.push_back(II->getUnwindDest()->getLandingPadInst());
-    }
-
-  if (Invokes.empty()) return false;
-
-  setupFunctionContext(F, LPads);
 
   // At this point, we are all set up, update the invoke instructions to mark
   // their call_site values, and fill in the dispatch switch accordingly.
@@ -880,6 +891,16 @@ bool SjLjEHPass::setupEntryBlockAndCallSites(Function &F) {
       }
   }
 
+  // Register the function context and make sure it's known to not throw
+  CallInst *Register = CallInst::Create(RegisterFn, FuncCtx.first, "",
+                                        EntryBB->getTerminator());
+  Register->setDoesNotThrow();
+
+  // Finally, for any returns from this function, if this function contains an
+  // invoke, add a call to unregister the function context.
+  for (unsigned I = 0, E = Returns.size(); I != E; ++I)
+    CallInst::Create(UnregisterFn, FuncCtx.first, "", Returns[I]);
+
   return true;
 }