From 09c84f13c6662e680f86e16f2474adf6177cf52f Mon Sep 17 00:00:00 2001
From: Michael Gottesman <mgottesman@apple.com>
Date: Wed, 16 Jan 2013 06:32:39 +0000
Subject: [PATCH] [ObjCARC] Turn off ignoring unwind edges in ObjCARC when
 -fno-objc-arc-exception is enabled due to it's affect on correctness.

Specifically according to the semantics of ARC -fno-objc-arc-exception simply
states that it is expected that the unwind path out of a call *MAY* not release
objects. Thus we can have the situation where a release gets moved into a catch
block which we ignore when we remove a retain/release pair resulting in (even
though we assume the program is exiting anyways) the cleanup code path
potentially blowing up before program exit.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172599 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/ObjCARC.cpp | 33 -------------------------------
 1 file changed, 33 deletions(-)

diff --git a/lib/Transforms/Scalar/ObjCARC.cpp b/lib/Transforms/Scalar/ObjCARC.cpp
index abd6b4185f6..8da87267665 100644
--- a/lib/Transforms/Scalar/ObjCARC.cpp
+++ b/lib/Transforms/Scalar/ObjCARC.cpp
@@ -2675,17 +2675,6 @@ ObjCARCOpt::CheckForCFGHazards(const BasicBlock *BB,
       PtrState &S = I->second;
       succ_const_iterator SI(TI), SE(TI, false);
 
-      // If the terminator is an invoke marked with the
-      // clang.arc.no_objc_arc_exceptions metadata, the unwind edge can be
-      // ignored, for ARC purposes.
-      if (isa<InvokeInst>(TI) && TI->getMetadata(NoObjCARCExceptionsMDKind)) {
-        DEBUG(dbgs() << "ObjCARCOpt::CheckForCFGHazards: Found an invoke "
-                        "terminator marked with "
-                        "clang.arc.no_objc_arc_exceptions. Ignoring unwind "
-                        "edge.\n");
-        --SE;
-      }
-
       for (; SI != SE; ++SI) {
         Sequence SuccSSeq = S_None;
         bool SuccSRRIKnownSafe = false;
@@ -2734,17 +2723,6 @@ ObjCARCOpt::CheckForCFGHazards(const BasicBlock *BB,
       PtrState &S = I->second;
       succ_const_iterator SI(TI), SE(TI, false);
 
-      // If the terminator is an invoke marked with the
-      // clang.arc.no_objc_arc_exceptions metadata, the unwind edge can be
-      // ignored, for ARC purposes.
-      if (isa<InvokeInst>(TI) && TI->getMetadata(NoObjCARCExceptionsMDKind)) {
-        DEBUG(dbgs() << "ObjCARCOpt::CheckForCFGHazards: Found an invoke "
-                        "terminator marked with "
-                        "clang.arc.no_objc_arc_exceptions. Ignoring unwind "
-                        "edge.\n");
-        --SE;
-      }
-
       for (; SI != SE; ++SI) {
         Sequence SuccSSeq = S_None;
         bool SuccSRRIKnownSafe = false;
@@ -3199,17 +3177,6 @@ ComputePostOrders(Function &F,
     TerminatorInst *TI = cast<TerminatorInst>(&CurrBB->back());
     succ_iterator SE(TI, false);
 
-    // If the terminator is an invoke marked with the
-    // clang.arc.no_objc_arc_exceptions metadata, the unwind edge can be
-    // ignored, for ARC purposes.
-    if (isa<InvokeInst>(TI) && TI->getMetadata(NoObjCARCExceptionsMDKind)) {
-        DEBUG(dbgs() << "ObjCARCOpt::ComputePostOrders: Found an invoke "
-                        "terminator marked with "
-                        "clang.arc.no_objc_arc_exceptions. Ignoring unwind "
-                        "edge.\n");
-      --SE;
-    }
-
     while (SuccStack.back().second != SE) {
       BasicBlock *SuccBB = *SuccStack.back().second++;
       if (Visited.insert(SuccBB)) {