From a33ef4816d2c192e36e7c025d18c66e89ef9d311 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Wed, 30 Mar 2005 01:10:47 +0000
Subject: [PATCH] Instead of setting up the CFG edges at selectiondag
 construction time, set them up after the code has been emitted.  This allows
 targets to select one mbb as multiple mbb's as needed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@20937 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp | 22 +++++++++++++------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index ded66afaa1b..9871cb32c16 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -414,7 +414,6 @@ void SelectionDAGLowering::visitRet(ReturnInst &I) {
 void SelectionDAGLowering::visitBr(BranchInst &I) {
   // Update machine-CFG edges.
   MachineBasicBlock *Succ0MBB = FuncInfo.MBBMap[I.getSuccessor(0)];
-  CurMBB->addSuccessor(Succ0MBB);
 
   // Figure out which block is immediately after the current one.
   MachineBasicBlock *NextBlock = 0;
@@ -429,7 +428,6 @@ void SelectionDAGLowering::visitBr(BranchInst &I) {
 			      DAG.getBasicBlock(Succ0MBB)));
   } else {
     MachineBasicBlock *Succ1MBB = FuncInfo.MBBMap[I.getSuccessor(1)];
-    CurMBB->addSuccessor(Succ1MBB);
 
     SDOperand Cond = getValue(I.getCondition());
 
@@ -893,7 +891,8 @@ LowerArguments(BasicBlock *BB, SelectionDAGLowering &SDL,
     // anything special.
     if (OldRoot != SDL.DAG.getRoot()) {
       unsigned a = 0;
-      for (Function::arg_iterator AI = F.arg_begin(), E = F.arg_end(); AI != E; ++AI,++a)
+      for (Function::arg_iterator AI = F.arg_begin(), E = F.arg_end();
+           AI != E; ++AI,++a)
         if (!AI->use_empty()) {
           SDL.setValue(AI, Args[a]);
           SDOperand Copy = 
@@ -904,7 +903,8 @@ LowerArguments(BasicBlock *BB, SelectionDAGLowering &SDL,
       // Otherwise, if any argument is only accessed in a single basic block,
       // emit that argument only to that basic block.
       unsigned a = 0;
-      for (Function::arg_iterator AI = F.arg_begin(), E = F.arg_end(); AI != E; ++AI,++a)
+      for (Function::arg_iterator AI = F.arg_begin(), E = F.arg_end();
+           AI != E; ++AI,++a)
         if (!AI->use_empty()) {
           if (BasicBlock *BBU = IsOnlyUsedInOneBasicBlock(AI)) {
             FuncInfo.BlockLocalArguments.insert(std::make_pair(BBU,
@@ -1058,8 +1058,8 @@ void SelectionDAGISel::SelectBasicBlock(BasicBlock *LLVMBB, MachineFunction &MF,
   DEBUG(std::cerr << "Legalized selection DAG:\n");
   DEBUG(DAG.dump());
 
-  // Finally, instruction select all of the operations to machine code, adding
-  // the code to the MachineBasicBlock.
+  // Third, instruction select all of the operations to machine code, adding the
+  // code to the MachineBasicBlock.
   InstructionSelectBasicBlock(DAG);
 
   if (ViewDAGs) DAG.viewGraph();
@@ -1067,7 +1067,7 @@ void SelectionDAGISel::SelectBasicBlock(BasicBlock *LLVMBB, MachineFunction &MF,
   DEBUG(std::cerr << "Selected machine code:\n");
   DEBUG(BB->dump());
 
-  // Finally, now that we know what the last MBB the LLVM BB expanded is, update
+  // Next, now that we know what the last MBB the LLVM BB expanded is, update
   // PHI nodes in successors.
   for (unsigned i = 0, e = PHINodesToUpdate.size(); i != e; ++i) {
     MachineInstr *PHI = PHINodesToUpdate[i].first;
@@ -1076,4 +1076,12 @@ void SelectionDAGISel::SelectBasicBlock(BasicBlock *LLVMBB, MachineFunction &MF,
     PHI->addRegOperand(PHINodesToUpdate[i].second);
     PHI->addMachineBasicBlockOperand(BB);
   }
+
+  // Finally, add the CFG edges from the last selected MBB to the successor
+  // MBBs.
+  TerminatorInst *TI = LLVMBB->getTerminator();
+  for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) {
+    MachineBasicBlock *Succ0MBB = FuncInfo.MBBMap[TI->getSuccessor(i)];
+    BB->addSuccessor(Succ0MBB);
+  }
 }