When initializing thread-safe statics, put the call to

__cxa_guard_abort along the exceptional edge into (in effect) a nested
"try" that rethrows after aborting. Fixes PR7144 and the remaining
Boost.ProgramOptions failures, along with the regressions that r103880
caused.

The crucial difference between this and r103880 is that we now follow
LLVM's little dance with the llvm.eh.exception and llvm.eh.selector
calls, then use _Unwind_Resume_or_Rethrow to rethrow.

llvm-svn: 103892

3 files changed, 76 insertions, 19 deletions

diff --git a/clang/lib/CodeGen/CGDeclCXX.cpp b/clang/lib/CodeGen/CGDeclCXX.cpp
index 036be928852..f94ddd98866 100644
--- a/clang/lib/CodeGen/CGDeclCXX.cpp
+++ b/clang/lib/CodeGen/CGDeclCXX.cpp
@@ -13,6 +13,8 @@
 
 #include "CodeGenFunction.h"
 #include "clang/CodeGen/CodeGenOptions.h"
+#include "llvm/Intrinsics.h"
+
 using namespace clang;
 using namespace CodeGen;
 
@@ -321,7 +323,10 @@ CodeGenFunction::EmitStaticCXXBlockVarDeclInit(const VarDecl &D,
 
   EmitBlock(InitCheckBlock);
 
-  if (ThreadsafeStatics) {
+  // Variables used when coping with thread-safe statics and exceptions.
+  llvm::BasicBlock *SavedLandingPad = 0;
+  llvm::BasicBlock *LandingPad = 0;
+  if (ThreadsafeStatics) {    
     // Call __cxa_guard_acquire.
     V = Builder.CreateCall(getGuardAcquireFn(*this), GuardVariable);
                
@@ -330,14 +335,13 @@ CodeGenFunction::EmitStaticCXXBlockVarDeclInit(const VarDecl &D,
     Builder.CreateCondBr(Builder.CreateIsNotNull(V, "tobool"),
                          InitBlock, EndBlock);
   
-    EmitBlock(InitBlock);
-
     if (Exceptions) {
-      EHCleanupBlock Cleanup(*this);
-    
-      // Call __cxa_guard_abort.
-      Builder.CreateCall(getGuardAbortFn(*this), GuardVariable);
+      SavedLandingPad = getInvokeDest();
+      LandingPad = createBasicBlock("guard.lpad");
+      setInvokeDest(LandingPad);
     }
+    
+    EmitBlock(InitBlock);
   }
 
   if (D.getType()->isReferenceType()) {
@@ -353,7 +357,7 @@ CodeGenFunction::EmitStaticCXXBlockVarDeclInit(const VarDecl &D,
 
   if (ThreadsafeStatics) {
     // Call __cxa_guard_release.
-    Builder.CreateCall(getGuardReleaseFn(*this), GuardVariable);
+    Builder.CreateCall(getGuardReleaseFn(*this), GuardVariable);    
   } else {
     llvm::Value *One = 
       llvm::ConstantInt::get(llvm::Type::getInt8Ty(VMContext), 1);
@@ -364,5 +368,57 @@ CodeGenFunction::EmitStaticCXXBlockVarDeclInit(const VarDecl &D,
   if (!D.getType()->isReferenceType())
     EmitDeclDestroy(*this, D, GV);
   
+  if (ThreadsafeStatics && Exceptions) {
+    // If an exception is thrown during initialization, call __cxa_guard_abort
+    // along the exceptional edge.
+    EmitBranch(EndBlock);
+    
+    // Construct the landing pad.
+    EmitBlock(LandingPad);
+        
+    // Personality function and LLVM intrinsics.
+    llvm::Constant *Personality =
+      CGM.CreateRuntimeFunction(llvm::FunctionType::get(llvm::Type::getInt32Ty
+                                                        (VMContext),
+                                                        true),
+                                "__gxx_personality_v0");
+    Personality = llvm::ConstantExpr::getBitCast(Personality, PtrToInt8Ty);
+    llvm::Value *llvm_eh_exception =
+      CGM.getIntrinsic(llvm::Intrinsic::eh_exception);
+    llvm::Value *llvm_eh_selector =
+      CGM.getIntrinsic(llvm::Intrinsic::eh_selector);
+    
+    // Exception object
+    llvm::Value *Exc = Builder.CreateCall(llvm_eh_exception, "exc");
+    llvm::Value *RethrowPtr = CreateTempAlloca(Exc->getType(), "_rethrow");
+
+    // Call the selector function.
+    const llvm::PointerType *PtrToInt8Ty 
+      = llvm::PointerType::getUnqual(llvm::Type::getInt8Ty(VMContext));
+    llvm::Constant *Null = llvm::ConstantPointerNull::get(PtrToInt8Ty);
+    llvm::Value* SelectorArgs[3] = { Exc, Personality, Null };
+    Builder.CreateCall(llvm_eh_selector, SelectorArgs, SelectorArgs + 3,
+                           "selector");
+    Builder.CreateStore(Exc, RethrowPtr);
+                                
+    // Call __cxa_guard_abort along the exceptional edge.
+    Builder.CreateCall(getGuardAbortFn(*this), GuardVariable);
+
+    setInvokeDest(SavedLandingPad);
+
+    // Rethrow the current exception.
+    if (getInvokeDest()) {
+      llvm::BasicBlock *Cont = createBasicBlock("invoke.cont");
+      Builder.CreateInvoke(getUnwindResumeOrRethrowFn(), Cont,
+                           getInvokeDest(),
+                           Builder.CreateLoad(RethrowPtr));
+      EmitBlock(Cont);
+    } else
+      Builder.CreateCall(getUnwindResumeOrRethrowFn(),
+                         Builder.CreateLoad(RethrowPtr));
+    
+    Builder.CreateUnreachable();    
+  }    
+  
   EmitBlock(EndBlock);
 }
diff --git a/clang/lib/CodeGen/CGException.cpp b/clang/lib/CodeGen/CGException.cpp
index c1d05bf233b..9fa195235ff 100644
--- a/clang/lib/CodeGen/CGException.cpp
+++ b/clang/lib/CodeGen/CGException.cpp
@@ -100,17 +100,17 @@ static llvm::Constant *getUnexpectedFn(CodeGenFunction &CGF) {
   return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_call_unexpected");
 }
 
-static llvm::Constant *getUnwindResumeOrRethrowFn(CodeGenFunction &CGF) {
-  const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
+llvm::Constant *CodeGenFunction::getUnwindResumeOrRethrowFn() {
+  const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(getLLVMContext());
   std::vector<const llvm::Type*> Args(1, Int8PtrTy);
 
   const llvm::FunctionType *FTy =
-    llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()), Args,
+    llvm::FunctionType::get(llvm::Type::getVoidTy(getLLVMContext()), Args,
                             false);
 
-  if (CGF.CGM.getLangOptions().SjLjExceptions)
-    return CGF.CGM.CreateRuntimeFunction(FTy, "_Unwind_SjLj_Resume");
-  return CGF.CGM.CreateRuntimeFunction(FTy, "_Unwind_Resume_or_Rethrow");
+  if (CGM.getLangOptions().SjLjExceptions)
+    return CGM.CreateRuntimeFunction(FTy, "_Unwind_SjLj_Resume");
+  return CGM.CreateRuntimeFunction(FTy, "_Unwind_Resume_or_Rethrow");
 }
 
 static llvm::Constant *getTerminateFn(CodeGenFunction &CGF) {
@@ -397,7 +397,7 @@ void CodeGenFunction::EmitStartEHSpec(const Decl *D) {
 
   if (Proto->getNumExceptions()) {
     EmitBlock(Unwind);
-    Builder.CreateCall(getUnwindResumeOrRethrowFn(*this),
+    Builder.CreateCall(getUnwindResumeOrRethrowFn(),
                        Builder.CreateLoad(RethrowPtr));
     Builder.CreateUnreachable();
   }
@@ -631,12 +631,12 @@ void CodeGenFunction::ExitCXXTryStmt(const CXXTryStmt &S,
   // here.
   if (getInvokeDest()) {
     llvm::BasicBlock *Cont = createBasicBlock("invoke.cont");
-    Builder.CreateInvoke(getUnwindResumeOrRethrowFn(*this), Cont,
+    Builder.CreateInvoke(getUnwindResumeOrRethrowFn(), Cont,
                          getInvokeDest(),
                          Builder.CreateLoad(RethrowPtr));
     EmitBlock(Cont);
   } else
-    Builder.CreateCall(getUnwindResumeOrRethrowFn(*this),
+    Builder.CreateCall(getUnwindResumeOrRethrowFn(),
                        Builder.CreateLoad(RethrowPtr));
 
   Builder.CreateUnreachable();
@@ -687,11 +687,11 @@ CodeGenFunction::EHCleanupBlock::~EHCleanupBlock() {
   // Rethrow the exception.
   if (CGF.getInvokeDest()) {
     llvm::BasicBlock *Cont = CGF.createBasicBlock("invoke.cont");
-    CGF.Builder.CreateInvoke(getUnwindResumeOrRethrowFn(CGF), Cont,
+    CGF.Builder.CreateInvoke(CGF.getUnwindResumeOrRethrowFn(), Cont,
                              CGF.getInvokeDest(), Exc);
     CGF.EmitBlock(Cont);
   } else
-    CGF.Builder.CreateCall(getUnwindResumeOrRethrowFn(CGF), Exc);
+    CGF.Builder.CreateCall(CGF.getUnwindResumeOrRethrowFn(), Exc);
   CGF.Builder.CreateUnreachable();
 
   // Resume inserting where we started, but put the new cleanup
diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index 151c13c8088..4f85878f0c0 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -929,6 +929,7 @@ public:
   void EmitObjCAtThrowStmt(const ObjCAtThrowStmt &S);
   void EmitObjCAtSynchronizedStmt(const ObjCAtSynchronizedStmt &S);
 
+  llvm::Constant *getUnwindResumeOrRethrowFn();
   struct CXXTryStmtInfo {
     llvm::BasicBlock *SavedLandingPad;
     llvm::BasicBlock *HandlerBlock;