From: Anders Carlsson <andersca@mac.com>
Date: Fri, 11 Dec 2009 00:32:37 +0000 (+0000)
Subject: When an exception needs to be freed by calling __cxa_exception_free, make sure to... 
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=8370c58b9295b32bee50443fe3ac43a47a2047e8;p=clang

When an exception needs to be freed by calling __cxa_exception_free, make sure to stash away the exception pointer somewhere.

This fixes an "Instruction does not dominate all uses!" verification error when compiling TableGen.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@91084 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/CGException.cpp b/lib/CodeGen/CGException.cpp
index b460fa9be0..07e7546637 100644
--- a/lib/CodeGen/CGException.cpp
+++ b/lib/CodeGen/CGException.cpp
@@ -127,21 +127,24 @@ static llvm::Constant *getTerminateFn(CodeGenFunction &CGF) {
 }
 
 // CopyObject - Utility to copy an object.  Calls copy constructor as necessary.
-// N is casted to the right type.
-static void CopyObject(CodeGenFunction &CGF, const Expr *E, llvm::Value *N) {
+// DestPtr is casted to the right type.
+static void CopyObject(CodeGenFunction &CGF, const Expr *E, 
+                       llvm::Value *DestPtr, llvm::Value *ExceptionPtrPtr) {
   QualType ObjectType = E->getType();
 
   // Store the throw exception in the exception object.
   if (!CGF.hasAggregateLLVMType(ObjectType)) {
     llvm::Value *Value = CGF.EmitScalarExpr(E);
-    const llvm::Type *ValuePtrTy = Value->getType()->getPointerTo(0);
+    const llvm::Type *ValuePtrTy = Value->getType()->getPointerTo();
 
-    CGF.Builder.CreateStore(Value, CGF.Builder.CreateBitCast(N, ValuePtrTy));
+    CGF.Builder.CreateStore(Value, 
+                            CGF.Builder.CreateBitCast(DestPtr, ValuePtrTy));
   } else {
-    const llvm::Type *Ty = CGF.ConvertType(ObjectType)->getPointerTo(0);
-    const CXXRecordDecl *RD;
-    RD = cast<CXXRecordDecl>(ObjectType->getAs<RecordType>()->getDecl());
-    llvm::Value *This = CGF.Builder.CreateBitCast(N, Ty);
+    const llvm::Type *Ty = CGF.ConvertType(ObjectType)->getPointerTo();
+    const CXXRecordDecl *RD =
+      cast<CXXRecordDecl>(ObjectType->getAs<RecordType>()->getDecl());
+    
+    llvm::Value *This = CGF.Builder.CreateBitCast(DestPtr, Ty);
     if (RD->hasTrivialCopyConstructor()) {
       CGF.EmitAggExpr(E, This, false);
     } else if (CXXConstructorDecl *CopyCtor
@@ -150,9 +153,9 @@ static void CopyObject(CodeGenFunction &CGF, const Expr *E, llvm::Value *N) {
       if (CGF.Exceptions) {
         CodeGenFunction::EHCleanupBlock Cleanup(CGF);
         llvm::Constant *FreeExceptionFn = getFreeExceptionFn(CGF);
-        const llvm::Type *Int8PtrTy
-          = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
-        llvm::Value *ExceptionPtr = CGF.Builder.CreateBitCast(N, Int8PtrTy);
+        
+        // Load the exception pointer.
+        llvm::Value *ExceptionPtr = CGF.Builder.CreateLoad(ExceptionPtrPtr);
         CGF.Builder.CreateCall(FreeExceptionFn, ExceptionPtr);
       }
 
@@ -251,8 +254,13 @@ void CodeGenFunction::EmitCXXThrowExpr(const CXXThrowExpr *E) {
     Builder.CreateCall(AllocExceptionFn,
                        llvm::ConstantInt::get(SizeTy, TypeSize),
                        "exception");
+  
+  llvm::Value *ExceptionPtrPtr = 
+    CreateTempAlloca(ExceptionPtr->getType(), "exception.ptr");
+  Builder.CreateStore(ExceptionPtr, ExceptionPtrPtr);
+
 
-  CopyObject(*this, E->getSubExpr(), ExceptionPtr);
+  CopyObject(*this, E->getSubExpr(), ExceptionPtr, ExceptionPtrPtr);
 
   // Now throw the exception.
   const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(getLLVMContext());
diff --git a/test/CodeGenCXX/eh.cpp b/test/CodeGenCXX/eh.cpp
index ec457dd418..5570fb44c2 100644
--- a/test/CodeGenCXX/eh.cpp
+++ b/test/CodeGenCXX/eh.cpp
@@ -11,7 +11,9 @@ void test1() {
 
 // CHECK:     define void @_Z5test1v() nounwind {
 // CHECK-NEXT:entry:
+// CHECK-NEXT:  %exception.ptr = alloca i8*
 // CHECK-NEXT:  %exception = call i8* @__cxa_allocate_exception(i64 8)
+// CHECK-NEXT:  store i8* %exception, i8** %exception.ptr
 // CHECK-NEXT:  %0 = bitcast i8* %exception to %struct.test1_D*
 // CHECK-NEXT:  %tmp = bitcast %struct.test1_D* %0 to i8*
 // CHECK-NEXT:  call void @llvm.memcpy.i64(i8* %tmp, i8* bitcast (%struct.test1_D* @d1 to i8*), i64 8, i32 8)
@@ -32,7 +34,9 @@ void test2() {
 
 // CHECK:     define void @_Z5test2v() nounwind {
 // CHECK-NEXT:entry:
+// CHECK-NEXT:  %exception.ptr = alloca i8*
 // CHECK-NEXT:  %exception = call i8* @__cxa_allocate_exception(i64 16)
+// CHECK-NEXT:  store i8* %exception, i8** %exception.ptr
 // CHECK-NEXT:  %0 = bitcast i8* %exception to %struct.test2_D*
 // CHECK:       invoke void @_ZN7test2_DC1ERKS_(%struct.test2_D* %0, %struct.test2_D* @d2)
 // CHECK-NEXT:     to label %invoke.cont unwind label %terminate.handler
@@ -52,7 +56,9 @@ void test3() {
 
 // CHECK:     define void @_Z5test3v() nounwind {
 // CHECK-NEXT: entry:
+// CHECK-NEXT:   %exception.ptr = alloca i8*
 // CHECK-NEXT:   %exception = call i8* @__cxa_allocate_exception(i64 8)
+// CHECK-NEXT:   store i8* %exception, i8** %exception.ptr
 // CHECK-NEXT:   %0 = bitcast i8* %exception to %struct.test3_D**
 // CHECK-NEXT:   store %struct.test3_D* null, %struct.test3_D** %0
 // CHECK-NEXT:   call void @__cxa_throw(i8* %exception, i8* bitcast (%1* @_ZTIPV7test3_D to i8*), i8* null) noreturn
diff --git a/test/CodeGenCXX/exceptions.cpp b/test/CodeGenCXX/exceptions.cpp
new file mode 100644
index 0000000000..396ff441ef
--- /dev/null
+++ b/test/CodeGenCXX/exceptions.cpp
@@ -0,0 +1,18 @@
+// RUN: clang-cc %s -triple=x86_64-apple-darwin10 -emit-llvm -o - -fexceptions
+
+struct allocator {
+  allocator();
+  allocator(const allocator&);
+  ~allocator();
+};
+
+void f();
+void g(bool b, bool c) {
+  if (b) {
+    if (!c)
+    throw allocator();
+
+    return;
+  }
+  f();
+}