From 2acf638216d98a4dcfed41828a4764cf9e68b4d4 Mon Sep 17 00:00:00 2001
From: Bill Wendling <isanbard@gmail.com>
Date: Fri, 7 Oct 2011 23:18:02 +0000
Subject: [PATCH] Take all of the invoke basic blocks and make the dispatch
 basic block their new successor. Remove the old landing pad from their
 successor list, because it's now the successor of the dispatch block. Now
 that the landing pad blocks are no longer the destination of invokes, we can
 mark them as normal basic blocks instead of landing pads.

This more closely resembles what the CFG is actually doing.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141436 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/ARM/ARMISelLowering.cpp | 32 ++++++++++++++++++++++++++----
 1 file changed, 28 insertions(+), 4 deletions(-)

diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index ab0c5589687..0313f99908c 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -5699,12 +5699,15 @@ EmitSjLjDispatchBlock(MachineInstr *MI, MachineBasicBlock *MBB) const {
 
   // Get an ordered list of the machine basic blocks for the jump table.
   std::vector<MachineBasicBlock*> LPadList;
+  SmallPtrSet<MachineBasicBlock*, 64> InvokeBBs;
   LPadList.reserve(CallSiteNumToLPad.size());
   for (unsigned I = 1; I <= MaxCSNum; ++I) {
     SmallVectorImpl<MachineBasicBlock*> &MBBList = CallSiteNumToLPad[I];
     for (SmallVectorImpl<MachineBasicBlock*>::iterator
-           II = MBBList.begin(), IE = MBBList.end(); II != IE; ++II)
+           II = MBBList.begin(), IE = MBBList.end(); II != IE; ++II) {
       LPadList.push_back(*II);
+      InvokeBBs.insert((*II)->pred_begin(), (*II)->pred_end());
+    }
   }
 
   assert(!LPadList.empty() &&
@@ -5721,7 +5724,6 @@ EmitSjLjDispatchBlock(MachineInstr *MI, MachineBasicBlock *MBB) const {
   // Shove the dispatch's address into the return slot in the function context.
   MachineBasicBlock *DispatchBB = MF->CreateMachineBasicBlock();
   DispatchBB->setIsLandingPad();
-  MBB->addSuccessor(DispatchBB);
 
   MachineBasicBlock *TrapBB = MF->CreateMachineBasicBlock();
   BuildMI(TrapBB, dl, TII->get(Subtarget->isThumb() ? ARM::tTRAP : ARM::TRAP));
@@ -5873,9 +5875,31 @@ EmitSjLjDispatchBlock(MachineInstr *MI, MachineBasicBlock *MBB) const {
   }
 
   // Add the jump table entries as successors to the MBB.
+  MachineBasicBlock *PrevMBB = 0;
   for (std::vector<MachineBasicBlock*>::iterator
-         I = LPadList.begin(), E = LPadList.end(); I != E; ++I)
-    DispContBB->addSuccessor(*I);
+         I = LPadList.begin(), E = LPadList.end(); I != E; ++I) {
+    MachineBasicBlock *CurMBB = *I;
+    if (PrevMBB != CurMBB)
+      DispContBB->addSuccessor(CurMBB);
+    PrevMBB = CurMBB;
+  }
+
+  // Remove the landing pad successor from the invoke block and replace it with
+  // the new dispatch block.
+  for (SmallPtrSet<MachineBasicBlock*, 64>::iterator
+         I = InvokeBBs.begin(), E = InvokeBBs.end(); I != E; ++I) {
+    MachineBasicBlock *BB = *I;
+    for (MachineBasicBlock::succ_iterator
+           SI = BB->succ_begin(), SE = BB->succ_end(); SI != SE; ++SI) {
+      MachineBasicBlock *SMBB = *SI;
+      if (SMBB->isLandingPad()) {
+        BB->removeSuccessor(SMBB);
+        SMBB->setIsLandingPad(false);
+      }
+    }
+
+    BB->addSuccessor(DispatchBB);
+  }
 
   // The instruction is gone now.
   MI->eraseFromParent();
-- 
2.34.1