From 0f5a1930ccf169f9a2885bff18e3169af4aff2a4 Mon Sep 17 00:00:00 2001
From: Sebastian Redl <sebastian.redl@getdesigned.at>
Date: Wed, 22 Feb 2012 17:37:59 +0000
Subject: [PATCH] Unwind path cleanup for array new list initializers.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@151172 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/CGExprCXX.cpp                     | 39 ++++++++++++++----
 test/CodeGenCXX/new-array-init-exceptions.cpp | 40 +++++++++++++++++++
 2 files changed, 72 insertions(+), 7 deletions(-)
 create mode 100644 test/CodeGenCXX/new-array-init-exceptions.cpp

diff --git a/lib/CodeGen/CGExprCXX.cpp b/lib/CodeGen/CGExprCXX.cpp
index af9c766238..00fbe9bfb0 100644
--- a/lib/CodeGen/CGExprCXX.cpp
+++ b/lib/CodeGen/CGExprCXX.cpp
@@ -804,12 +804,32 @@ CodeGenFunction::EmitNewArrayInitializer(const CXXNewExpr *E,
   unsigned initializerElements = 0;
 
   const Expr *Init = E->getInitializer();
+  llvm::AllocaInst *endOfInit = 0;
+  QualType::DestructionKind dtorKind = elementType.isDestructedType();
+  EHScopeStack::stable_iterator cleanup;
+  llvm::Instruction *cleanupDominator = 0;
   // If the initializer is an initializer list, first do the explicit elements.
   if (const InitListExpr *ILE = dyn_cast<InitListExpr>(Init)) {
     initializerElements = ILE->getNumInits();
-    QualType elementType = E->getAllocatedType();
-    // FIXME: exception-safety for the explicit initializers
+
+    // Enter a partial-destruction cleanup if necessary.
+    if (needsEHCleanup(dtorKind)) {
+      // In principle we could tell the cleanup where we are more
+      // directly, but the control flow can get so varied here that it
+      // would actually be quite complex.  Therefore we go through an
+      // alloca.
+      endOfInit = CreateTempAlloca(beginPtr->getType(), "array.endOfInit");
+      cleanupDominator = Builder.CreateStore(beginPtr, endOfInit);
+      pushIrregularPartialArrayCleanup(beginPtr, endOfInit, elementType,
+                                       getDestroyer(dtorKind));
+      cleanup = EHStack.stable_begin();
+    }
+
     for (unsigned i = 0, e = ILE->getNumInits(); i != e; ++i) {
+      // Tell the cleanup that it needs to destroy up to this
+      // element.  TODO: some of these stores can be trivially
+      // observed to be unnecessary.
+      if (endOfInit) Builder.CreateStore(explicitPtr, endOfInit);
       StoreAnyExprIntoOneUnit(*this, ILE->getInit(i), elementType, explicitPtr);
       explicitPtr =Builder.CreateConstGEP1_32(explicitPtr, 1, "array.exp.next");
     }
@@ -825,7 +845,12 @@ CodeGenFunction::EmitNewArrayInitializer(const CXXNewExpr *E,
   // anything left to initialize.
   if (llvm::ConstantInt *constNum = dyn_cast<llvm::ConstantInt>(numElements)) {
     // If all elements have already been initialized, skip the whole loop.
-    if (constNum->getZExtValue() <= initializerElements) return;
+    if (constNum->getZExtValue() <= initializerElements) {
+      // If there was a cleanup, deactivate it.
+      if (cleanupDominator)
+        DeactivateCleanupBlock(cleanup, cleanupDominator);;
+      return;
+    }
   } else {
     llvm::BasicBlock *nonEmptyBB = createBasicBlock("new.loop.nonempty");
     llvm::Value *isEmpty = Builder.CreateICmpEQ(explicitPtr, endPtr,
@@ -845,11 +870,11 @@ CodeGenFunction::EmitNewArrayInitializer(const CXXNewExpr *E,
     Builder.CreatePHI(explicitPtr->getType(), 2, "array.cur");
   curPtr->addIncoming(explicitPtr, entryBB);
 
+  // Store the new cleanup position for irregular cleanups.
+  if (endOfInit) Builder.CreateStore(curPtr, endOfInit);
+
   // Enter a partial-destruction cleanup if necessary.
-  QualType::DestructionKind dtorKind = elementType.isDestructedType();
-  EHScopeStack::stable_iterator cleanup;
-  llvm::Instruction *cleanupDominator = 0;
-  if (needsEHCleanup(dtorKind)) {
+  if (!cleanupDominator && needsEHCleanup(dtorKind)) {
     pushRegularPartialArrayCleanup(beginPtr, curPtr, elementType,
                                    getDestroyer(dtorKind));
     cleanup = EHStack.stable_begin();
diff --git a/test/CodeGenCXX/new-array-init-exceptions.cpp b/test/CodeGenCXX/new-array-init-exceptions.cpp
new file mode 100644
index 0000000000..933f7f7553
--- /dev/null
+++ b/test/CodeGenCXX/new-array-init-exceptions.cpp
@@ -0,0 +1,40 @@
+// RUN: %clang_cc1 -std=c++11 -triple i386-unknown-unknown -fexceptions -fcxx-exceptions %s -emit-llvm -o - | FileCheck %s
+
+struct Throws {
+  Throws(int);
+  Throws();
+  ~Throws();
+};
+
+// CHECK: define void @_Z7cleanupi
+void cleanup(int n) {
+  // CHECK: invoke void @_ZN6ThrowsC1Ei
+  // CHECK-NEXT: to label %{{[^ ]+}} unwind label %[[LPAD:[^ ]+]]
+  // CHECK: invoke void @_ZN6ThrowsC1Ei
+  // CHECK-NEXT: to label %{{[^ ]+}} unwind label %[[LPAD]]
+  // CHECK: invoke void @_ZN6ThrowsC1Ei
+  // CHECK-NEXT: to label %{{[^ ]+}} unwind label %[[LPAD]]
+  // CHECK: invoke void @_ZN6ThrowsC1Ev
+  // CHECK-NEXT: to label %{{[^ ]+}} unwind label %[[LPAD]]
+  new Throws[n] { 1, 2, 3 };
+  // CHECK: [[LPAD]]:
+  // CHECK-NEXT: landingpad
+  // CHECK: call void @_ZN6ThrowsD1Ev
+  // CHECK: call void @_ZdaPv
+}
+
+
+// CHECK: define void @_Z7cleanupv
+void cleanup() {
+  // CHECK: invoke void @_ZN6ThrowsC1Ei
+  // CHECK-NEXT: to label %{{[^ ]+}} unwind label %[[LPAD2:[^ ]+]]
+  // CHECK: invoke void @_ZN6ThrowsC1Ei
+  // CHECK-NEXT: to label %{{[^ ]+}} unwind label %[[LPAD2]]
+  // CHECK: invoke void @_ZN6ThrowsC1Ei
+  // CHECK-NEXT: to label %{{[^ ]+}} unwind label %[[LPAD2]]
+  new Throws[3] { 1, 2, 3 };
+  // CHECK: [[LPAD2]]:
+  // CHECK-NEXT: landingpad
+  // CHECK: call void @_ZN6ThrowsD1Ev
+  // CHECK: call void @_ZdaPv
+}
-- 
2.40.0