Validated by nightly-test runs on x86 and x86-64 darwin, including after

self-host.  Hopefully these results hold up on different platforms.  

I tried to keep the GNU ObjC runtime happy, but it's hard for me to test.
Reimplement how clang generates IR for exceptions.  Instead of creating new
invoke destinations which sequentially chain to the previous destination,
push a more semantic representation of *why* we need the cleanup/catch/filter
behavior, then collect that information into a single landing pad upon request.

Also reorganizes how normal cleanups (i.e. cleanups triggered by non-exceptional
control flow) are generated, since it's actually fairly closely tied in with
the former.  Remove the need to track which cleanup scope a block is associated
with.

Document a lot of previously poorly-understood (by me, at least) behavior.

The new framework implements the Horrible Hack (tm), which requires every
landing pad to have a catch-all so that inlining will work.  Clang no longer
requires the Horrible Hack just to make exceptions flow correctly within
a function, however.  The HH is an unfortunate requirement of LLVM's EH IR.

llvm-svn: 107631

1 files changed, 23 insertions, 2 deletions

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 528a038f916..0a17e56d727 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -1075,6 +1075,24 @@ RValue CodeGenFunction::EmitCallArg(const Expr *E, QualType ArgType) {
   return EmitAnyExprToTemp(E);
 }
 
+/// Emits a call or invoke instruction to the given function, depending
+/// on the current state of the EH stack.
+llvm::CallSite
+CodeGenFunction::EmitCallOrInvoke(llvm::Value *Callee,
+                                  llvm::Value * const *ArgBegin,
+                                  llvm::Value * const *ArgEnd,
+                                  const llvm::Twine &Name) {
+  llvm::BasicBlock *InvokeDest = getInvokeDest();
+  if (!InvokeDest)
+    return Builder.CreateCall(Callee, ArgBegin, ArgEnd, Name);
+
+  llvm::BasicBlock *ContBB = createBasicBlock("invoke.cont");
+  llvm::InvokeInst *Invoke = Builder.CreateInvoke(Callee, ContBB, InvokeDest,
+                                                  ArgBegin, ArgEnd, Name);
+  EmitBlock(ContBB);
+  return Invoke;
+}
+
 RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
                                  llvm::Value *Callee,
                                  ReturnValueSlot ReturnValue,
@@ -1206,15 +1224,18 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
     }
 
 
-  llvm::BasicBlock *InvokeDest = getInvokeDest();
   unsigned CallingConv;
   CodeGen::AttributeListType AttributeList;
   CGM.ConstructAttributeList(CallInfo, TargetDecl, AttributeList, CallingConv);
   llvm::AttrListPtr Attrs = llvm::AttrListPtr::get(AttributeList.begin(),
                                                    AttributeList.end());
 
+  llvm::BasicBlock *InvokeDest = 0;
+  if (!(Attrs.getFnAttributes() & llvm::Attribute::NoUnwind))
+    InvokeDest = getInvokeDest();
+
   llvm::CallSite CS;
-  if (!InvokeDest || (Attrs.getFnAttributes() & llvm::Attribute::NoUnwind)) {
+  if (!InvokeDest) {
     CS = Builder.CreateCall(Callee, Args.data(), Args.data()+Args.size());
   } else {
     llvm::BasicBlock *Cont = createBasicBlock("invoke.cont");