From 0ad56122e585d3d27ea852115390a9e53cabc9d5 Mon Sep 17 00:00:00 2001
From: Bill Wendling <isanbard@gmail.com>
Date: Fri, 21 Oct 2011 22:08:56 +0000
Subject: Make sure that the landing pads themselves have no PHI instructions
 in them.

The assumption in the back-end is that PHIs are not allowed at the start of the
landing pad block for SjLj exceptions.
<rdar://problem/10313708>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142689 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/SjLjEHPrepare.cpp | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

(limited to 'lib/CodeGen/SjLjEHPrepare.cpp')

diff --git a/lib/CodeGen/SjLjEHPrepare.cpp b/lib/CodeGen/SjLjEHPrepare.cpp
index 3ccf39ba24..e5cb1bb6ea 100644
--- a/lib/CodeGen/SjLjEHPrepare.cpp
+++ b/lib/CodeGen/SjLjEHPrepare.cpp
@@ -908,6 +908,27 @@ void SjLjEHPass::lowerAcrossUnwindEdges(Function &F,
       }
     }
   }
+
+  // Go through the landing pads and remove any PHIs there.
+  for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
+    BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest();
+    LandingPadInst *LPI = UnwindBlock->getLandingPadInst();
+
+    // Place PHIs into a set to avoid invalidating the iterator.
+    SmallPtrSet<PHINode*, 8> PHIsToDemote;
+    for (BasicBlock::iterator
+           PN = UnwindBlock->begin(); isa<PHINode>(PN); ++PN)
+      PHIsToDemote.insert(cast<PHINode>(PN));
+    if (PHIsToDemote.empty()) continue;
+
+    // Demote the PHIs to the stack.
+    for (SmallPtrSet<PHINode*, 8>::iterator
+           I = PHIsToDemote.begin(), E = PHIsToDemote.end(); I != E; ++I)
+      DemotePHIToStack(*I);
+
+    // Move the landingpad instruction back to the top of the landing pad block.
+    LPI->moveBefore(UnwindBlock->begin());
+  }
 }
 
 /// setupEntryBlockAndCallSites - Setup the entry block by creating and filling
-- 
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