From 5c25a9201100a2e514f547da9c3c7c4a50b86546 Mon Sep 17 00:00:00 2001
From: Bill Wendling <isanbard@gmail.com>
Date: Tue, 15 Mar 2011 01:03:17 +0000
Subject: [PATCH] There are some situations which can cause the URoR hack to
 infinitely recurse and then go kablooie. The problem was that it was tracking
 the PHI nodes anew each time into this function. But it didn't need to. And
 because the recursion didn't know that a PHINode was visited before, it would
 go ahead and call itself.

There is a testcase, but unfortunately it's too big to add. This problem will go
away with the EH rewrite.
<rdar://problem/8856298>

llvm-svn: 127640
---
 llvm/lib/CodeGen/DwarfEHPrepare.cpp | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/llvm/lib/CodeGen/DwarfEHPrepare.cpp b/llvm/lib/CodeGen/DwarfEHPrepare.cpp
index 0ebb5b0db70e..d5a2ed977f3a 100644
--- a/llvm/lib/CodeGen/DwarfEHPrepare.cpp
+++ b/llvm/lib/CodeGen/DwarfEHPrepare.cpp
@@ -93,7 +93,8 @@ namespace {
     /// with the eh.exception call. This recursively looks past instructions
     /// which don't change the EH pointer value, like casts or PHI nodes.
     bool FindSelectorAndURoR(Instruction *Inst, bool &URoRInvoke,
-                             SmallPtrSet<IntrinsicInst*, 8> &SelCalls);
+                             SmallPtrSet<IntrinsicInst*, 8> &SelCalls,
+                             SmallPtrSet<PHINode*, 32> &SeenPHIs);
       
   public:
     static char ID; // Pass identification, replacement for typeid.
@@ -199,8 +200,8 @@ bool DwarfEHPrepare::CleanupSelectors(SmallPtrSet<IntrinsicInst*, 32> &Sels) {
 /// change the EH pointer value, like casts or PHI nodes.
 bool
 DwarfEHPrepare::FindSelectorAndURoR(Instruction *Inst, bool &URoRInvoke,
-                                    SmallPtrSet<IntrinsicInst*, 8> &SelCalls) {
-  SmallPtrSet<PHINode*, 32> SeenPHIs;
+                                    SmallPtrSet<IntrinsicInst*, 8> &SelCalls,
+                                    SmallPtrSet<PHINode*, 32> &SeenPHIs) {
   bool Changed = false;
 
   for (Value::use_iterator
@@ -215,11 +216,11 @@ DwarfEHPrepare::FindSelectorAndURoR(Instruction *Inst, bool &URoRInvoke,
       if (Invoke->getCalledFunction() == URoR)
         URoRInvoke = true;
     } else if (CastInst *CI = dyn_cast<CastInst>(II)) {
-      Changed |= FindSelectorAndURoR(CI, URoRInvoke, SelCalls);
+      Changed |= FindSelectorAndURoR(CI, URoRInvoke, SelCalls, SeenPHIs);
     } else if (PHINode *PN = dyn_cast<PHINode>(II)) {
       if (SeenPHIs.insert(PN))
         // Don't process a PHI node more than once.
-        Changed |= FindSelectorAndURoR(PN, URoRInvoke, SelCalls);
+        Changed |= FindSelectorAndURoR(PN, URoRInvoke, SelCalls, SeenPHIs);
     }
   }
 
@@ -294,7 +295,8 @@ bool DwarfEHPrepare::HandleURoRInvokes() {
 
       bool URoRInvoke = false;
       SmallPtrSet<IntrinsicInst*, 8> SelCalls;
-      Changed |= FindSelectorAndURoR(EHPtr, URoRInvoke, SelCalls);
+      SmallPtrSet<PHINode*, 32> SeenPHIs;
+      Changed |= FindSelectorAndURoR(EHPtr, URoRInvoke, SelCalls, SeenPHIs);
 
       if (URoRInvoke) {
         // This EH pointer is being used by an invoke of an URoR instruction and