Throw the switch to convert clang to the new exception handling model!

This model uses the 'landingpad' instruction, which is pinned to the top of the
landing pad. (A landing pad is defined as the destination of the unwind branch
of an invoke instruction.) All of the information needed to generate the correct
exception handling metadata during code generation is encoded into the
landingpad instruction.

The new 'resume' instruction takes the place of the llvm.eh.resume intrinsic
call. It's lowered in much the same way as the intrinsic is.

llvm-svn: 140049

1 files changed, 54 insertions, 59 deletions

diff --git a/clang/lib/CodeGen/CGException.cpp b/clang/lib/CodeGen/CGException.cpp
index e7119149557..14a89cff3f9 100644
--- a/clang/lib/CodeGen/CGException.cpp
+++ b/clang/lib/CodeGen/CGException.cpp
@@ -306,12 +306,6 @@ static llvm::Constant *getCatchAllValue(CodeGenFunction &CGF) {
   return llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
 }
 
-/// Returns the value to inject into a selector to indicate the
-/// presence of a cleanup.
-static llvm::Constant *getCleanupValue(CodeGenFunction &CGF) {
-  return llvm::ConstantInt::get(CGF.Builder.getInt32Ty(), 0);
-}
-
 namespace {
   /// A cleanup to free the exception object if its initialization
   /// throws.
@@ -733,17 +727,19 @@ llvm::BasicBlock *CodeGenFunction::EmitLandingPad() {
   llvm::BasicBlock *lpad = createBasicBlock("lpad");
   EmitBlock(lpad);
 
+  llvm::LandingPadInst *LPadInst =
+    Builder.CreateLandingPad(llvm::StructType::get(Int8PtrTy, Int32Ty, NULL),
+                             getOpaquePersonalityFn(CGM, personality), 0);
+
+  llvm::Value *LPadExn = Builder.CreateExtractValue(LPadInst, 0);
+  Builder.CreateStore(LPadExn, getExceptionSlot());
+  llvm::Value *LPadSel = Builder.CreateExtractValue(LPadInst, 1);
+  Builder.CreateStore(LPadSel, getEHSelectorSlot());
+
   // Save the exception pointer.  It's safe to use a single exception
   // pointer per function because EH cleanups can never have nested
   // try/catches.
-  llvm::CallInst *exn =
-    Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::eh_exception), "exn");
-  exn->setDoesNotThrow();
-  
-  // Build the selector arguments.
-  SmallVector<llvm::Value*, 8> selector;
-  selector.push_back(exn);
-  selector.push_back(getOpaquePersonalityFn(CGM, personality));
+  // Build the landingpad instruction.
 
   // Accumulate all the handlers in scope.
   bool hasCatchAll = false;
@@ -764,7 +760,7 @@ llvm::BasicBlock *CodeGenFunction::EmitLandingPad() {
       assert(I.next() == EHStack.end() && "EH filter is not end of EH stack");
       assert(!hasCatchAll && "EH filter reached after catch-all");
 
-      // Filter scopes get added to the selector in weird ways.
+      // Filter scopes get added to the landingpad in weird ways.
       EHFilterScope &filter = cast<EHFilterScope>(*I);
       hasFilter = true;
 
@@ -800,54 +796,52 @@ llvm::BasicBlock *CodeGenFunction::EmitLandingPad() {
       }
 
       // Check whether we already have a handler for this type.
-      if (catchTypes.insert(handler.Type)) {
-        // If not, add it directly to the selector.
-        selector.push_back(handler.Type);
-      }
+      if (catchTypes.insert(handler.Type))
+        // If not, add it directly to the landingpad.
+        LPadInst->addClause(handler.Type);
     }
   }
 
  done:
-  // If we have a catch-all, add null to the selector.
+  // If we have a catch-all, add null to the landingpad.
   assert(!(hasCatchAll && hasFilter));
   if (hasCatchAll) {
-    selector.push_back(getCatchAllValue(*this));
+    LPadInst->addClause(getCatchAllValue(*this));
 
   // If we have an EH filter, we need to add those handlers in the
-  // right place in the selector, which is to say, at the end.
+  // right place in the landingpad, which is to say, at the end.
   } else if (hasFilter) {
     // Create a filter expression: an integer constant saying how many
     // filters there are (+1 to avoid ambiguity with 0 for cleanup),
     // followed by the filter types.  The personality routine only
     // lands here if the filter doesn't match.
-    selector.push_back(Builder.getInt32(filterTypes.size() + 1));
-    selector.append(filterTypes.begin(), filterTypes.end());
+    llvm::SmallVector<llvm::Constant*, 8> Filters;
+    llvm::ArrayType *AType =
+      llvm::ArrayType::get(!filterTypes.empty() ?
+                             filterTypes[0]->getType() : Int8PtrTy,
+                           filterTypes.size());
+
+    for (unsigned i = 0, e = filterTypes.size(); i != e; ++i)
+      Filters.push_back(cast<llvm::Constant>(filterTypes[i]));
+    llvm::Constant *FilterArray = llvm::ConstantArray::get(AType, Filters);
+    LPadInst->addClause(FilterArray);
 
     // Also check whether we need a cleanup.
-    if (CleanupHackLevel == CHL_MandatoryCatchall || hasCleanup)
-      selector.push_back(CleanupHackLevel == CHL_MandatoryCatchall
-                           ? getCatchAllValue(*this)
-                           : getCleanupValue(*this));
+    if (hasCleanup)
+      LPadInst->setCleanup(true);
 
   // Otherwise, signal that we at least have cleanups.
   } else if (CleanupHackLevel == CHL_MandatoryCatchall || hasCleanup) {
-    selector.push_back(CleanupHackLevel == CHL_MandatoryCatchall
-                         ? getCatchAllValue(*this)
-                         : getCleanupValue(*this));
+    if (CleanupHackLevel == CHL_MandatoryCatchall)
+      LPadInst->addClause(getCatchAllValue(*this));
+    else
+      LPadInst->setCleanup(true);
   }
 
-  assert(selector.size() >= 3 && "selector call has only two arguments!");
+  assert((LPadInst->getNumClauses() > 0 || LPadInst->isCleanup()) &&
+         "landingpad instruction has no clauses!");
 
   // Tell the backend how to generate the landing pad.
-  llvm::CallInst *selectorCall =
-    Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::eh_selector),
-                       selector, "eh.selector");
-  selectorCall->setDoesNotThrow();
-
-  // Save the selector and exception pointer.
-  Builder.CreateStore(exn, getExceptionSlot());
-  Builder.CreateStore(selectorCall, getEHSelectorSlot());
-
   Builder.CreateBr(getEHDispatchBlock(EHStack.getInnermostEHScope()));
 
   // Restore the old IR generation state.
@@ -1462,19 +1456,11 @@ llvm::BasicBlock *CodeGenFunction::getTerminateLandingPad() {
   Builder.SetInsertPoint(TerminateLandingPad);
 
   // Tell the backend that this is a landing pad.
-  llvm::CallInst *Exn =
-    Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::eh_exception), "exn");
-  Exn->setDoesNotThrow();
-
   const EHPersonality &Personality = EHPersonality::get(CGM.getLangOptions());
-  
-  // Tell the backend what the exception table should be:
-  // nothing but a catch-all.
-  llvm::Value *Args[3] = { Exn, getOpaquePersonalityFn(CGM, Personality),
-                           getCatchAllValue(*this) };
-  Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::eh_selector),
-                     Args, "eh.selector")
-    ->setDoesNotThrow();
+  llvm::LandingPadInst *LPadInst =
+    Builder.CreateLandingPad(llvm::StructType::get(Int8PtrTy, Int32Ty, NULL),
+                             getOpaquePersonalityFn(CGM, Personality), 0);
+  LPadInst->addClause(getCatchAllValue(*this));
 
   llvm::CallInst *TerminateCall = Builder.CreateCall(getTerminateFn(*this));
   TerminateCall->setDoesNotReturn();
@@ -1538,12 +1524,21 @@ llvm::BasicBlock *CodeGenFunction::getEHResumeBlock() {
         ->setDoesNotReturn();
       break;
     case CHL_MandatoryCleanup: {
-      // In mandatory-cleanup mode, we should use llvm.eh.resume.
-      llvm::Value *Selector = getSelectorFromSlot();
-      Builder.CreateCall2(CGM.getIntrinsic(llvm::Intrinsic::eh_resume),
-                          Exn, Selector)
-        ->setDoesNotReturn();
-      break;
+      // In mandatory-cleanup mode, we should use 'resume'.
+
+      // Recreate the landingpad's return value for the 'resume' instruction.
+      llvm::Value *Exn = getExceptionFromSlot();
+      llvm::Value *Sel = getSelectorFromSlot();
+
+      llvm::Type *LPadType = llvm::StructType::get(Exn->getType(),
+                                                   Sel->getType(), NULL);
+      llvm::Value *LPadVal = llvm::UndefValue::get(LPadType);
+      LPadVal = Builder.CreateInsertValue(LPadVal, Exn, 0, "lpad.val");
+      LPadVal = Builder.CreateInsertValue(LPadVal, Sel, 1, "lpad.val");
+
+      Builder.CreateResume(LPadVal);
+      Builder.restoreIP(SavedIP);
+      return EHResumeBlock;
     }
     case CHL_Ideal:
       // In an idealized mode where we don't have to worry about the