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

1 files changed, 8 insertions, 6 deletions

diff --git a/llvm/lib/CodeGen/DwarfEHPrepare.cpp b/llvm/lib/CodeGen/DwarfEHPrepare.cpp
index 0ebb5b0db70..d5a2ed977f3 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