From 3de8249078354d25b37b40e0f10b4f88226d3dd4 Mon Sep 17 00:00:00 2001
From: Bill Wendling <isanbard@gmail.com>
Date: Thu, 17 Dec 2009 23:42:32 +0000
Subject: [PATCH] Turn off critical edge splitting for landing pads. The
 introduction of a non-landing pad basic block as the successor to a block
 that ends in an unconditional jump will cause block folding to remove the
 added block as a successor. Thus eventually removing it AND the landing pad
 entirely. Critical edge splitting is an optimization, so we can safely turn
 it off when dealing with landing pads.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91634 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/PHIElimination.cpp       | 7 ++++---
 lib/CodeGen/StrongPHIElimination.cpp | 2 +-
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/lib/CodeGen/PHIElimination.cpp b/lib/CodeGen/PHIElimination.cpp
index d11e01a0c30..58c3dec4c22 100644
--- a/lib/CodeGen/PHIElimination.cpp
+++ b/lib/CodeGen/PHIElimination.cpp
@@ -71,7 +71,7 @@ bool llvm::PHIElimination::runOnMachineFunction(MachineFunction &Fn) {
     Changed |= EliminatePHINodes(Fn, *I);
 
   // Remove dead IMPLICIT_DEF instructions.
-  for (SmallPtrSet<MachineInstr*,4>::iterator I = ImpDefs.begin(),
+  for (SmallPtrSet<MachineInstr*, 4>::iterator I = ImpDefs.begin(),
          E = ImpDefs.end(); I != E; ++I) {
     MachineInstr *DefMI = *I;
     unsigned DefReg = DefMI->getOperand(0).getReg();
@@ -83,8 +83,8 @@ bool llvm::PHIElimination::runOnMachineFunction(MachineFunction &Fn) {
   for (LoweredPHIMap::iterator I = LoweredPHIs.begin(), E = LoweredPHIs.end();
        I != E; ++I)
     Fn.DeleteMachineInstr(I->first);
-  LoweredPHIs.clear();
 
+  LoweredPHIs.clear();
   ImpDefs.clear();
   VRegPHIUseCount.clear();
   return Changed;
@@ -384,7 +384,8 @@ void llvm::PHIElimination::analyzePHINodes(const MachineFunction& Fn) {
 bool llvm::PHIElimination::SplitPHIEdges(MachineFunction &MF,
                                          MachineBasicBlock &MBB,
                                          LiveVariables &LV) {
-  if (MBB.empty() || MBB.front().getOpcode() != TargetInstrInfo::PHI)
+  if (MBB.empty() || MBB.front().getOpcode() != TargetInstrInfo::PHI ||
+      MBB.isLandingPad())
     return false;   // Quick exit for basic blocks without PHIs.
 
   for (MachineBasicBlock::const_iterator BBI = MBB.begin(), BBE = MBB.end();
diff --git a/lib/CodeGen/StrongPHIElimination.cpp b/lib/CodeGen/StrongPHIElimination.cpp
index 3c139068e68..345e22835ec 100644
--- a/lib/CodeGen/StrongPHIElimination.cpp
+++ b/lib/CodeGen/StrongPHIElimination.cpp
@@ -907,7 +907,7 @@ bool StrongPHIElimination::runOnMachineFunction(MachineFunction &Fn) {
   
   // Determine which phi node operands need copies
   for (MachineFunction::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I)
-    if (!I->empty() &&
+    if (!I->empty() && !I->isLandingPad() &&
         I->begin()->getOpcode() == TargetInstrInfo::PHI)
       processBlock(I);
   
-- 
2.34.1