From 7a7a6db6d79b53fdf01bbd9519e669424c3ea7a0 Mon Sep 17 00:00:00 2001
From: Nick Lewycky <nicholas@mxc.ca>
Date: Thu, 5 Jul 2012 06:19:21 +0000
Subject: [PATCH] Remove ParentMap. You can just ask the domnode for its
 parent. No functionality change.

Move the "Not profitable, avoid CSE!" debug message next to where we fail the
check for profitability and use a different message for avoiding CSE due to
being in different register classes.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159729 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/MachineCSE.cpp | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/lib/CodeGen/MachineCSE.cpp b/lib/CodeGen/MachineCSE.cpp
index f2539baabd8..b931517b4f9 100644
--- a/lib/CodeGen/MachineCSE.cpp
+++ b/lib/CodeGen/MachineCSE.cpp
@@ -84,7 +84,7 @@ namespace {
     bool PerformTrivialCoalescing(MachineInstr *MI, MachineBasicBlock *MBB);
     bool isPhysDefTriviallyDead(unsigned Reg,
                                 MachineBasicBlock::const_iterator I,
-                                MachineBasicBlock::const_iterator E) const ;
+                                MachineBasicBlock::const_iterator E) const;
     bool hasLivePhysRegDefUses(const MachineInstr *MI,
                                const MachineBasicBlock *MBB,
                                SmallSet<unsigned,8> &PhysRefs,
@@ -100,8 +100,7 @@ namespace {
     void ExitScope(MachineBasicBlock *MBB);
     bool ProcessBlock(MachineBasicBlock *MBB);
     void ExitScopeIfDone(MachineDomTreeNode *Node,
-                 DenseMap<MachineDomTreeNode*, unsigned> &OpenChildren,
-                 DenseMap<MachineDomTreeNode*, MachineDomTreeNode*> &ParentMap);
+			 DenseMap<MachineDomTreeNode*, unsigned> &OpenChildren);
     bool PerformCSE(MachineDomTreeNode *Node);
   };
 } // end anonymous namespace
@@ -436,7 +435,7 @@ bool MachineCSE::ProcessBlock(MachineBasicBlock *MBB) {
     // used, then it's not safe to replace it with a common subexpression.
     // It's also not safe if the instruction uses physical registers.
     bool CrossMBBPhysDef = false;
-    SmallSet<unsigned,8> PhysRefs;
+    SmallSet<unsigned, 8> PhysRefs;
     SmallVector<unsigned, 2> PhysDefs;
     if (FoundCSE && hasLivePhysRegDefUses(MI, MBB, PhysRefs, PhysDefs)) {
       FoundCSE = false;
@@ -479,6 +478,7 @@ bool MachineCSE::ProcessBlock(MachineBasicBlock *MBB) {
              "Do not CSE physical register defs!");
 
       if (!isProfitableToCSE(NewReg, OldReg, CSMI, MI)) {
+        DEBUG(dbgs() << "*** Not profitable, avoid CSE!\n");
         DoCSE = false;
         break;
       }
@@ -487,6 +487,7 @@ bool MachineCSE::ProcessBlock(MachineBasicBlock *MBB) {
       // within the register class of the new instruction.
       const TargetRegisterClass *OldRC = MRI->getRegClass(OldReg);
       if (!MRI->constrainRegClass(NewReg, OldRC)) {
+        DEBUG(dbgs() << "*** Not the same register class, avoid CSE!\n");
         DoCSE = false;
         break;
       }
@@ -521,7 +522,6 @@ bool MachineCSE::ProcessBlock(MachineBasicBlock *MBB) {
         ++NumCommutes;
       Changed = true;
     } else {
-      DEBUG(dbgs() << "*** Not profitable, avoid CSE!\n");
       VNT.insert(MI, CurrVN++);
       Exps.push_back(MI);
     }
@@ -536,8 +536,7 @@ bool MachineCSE::ProcessBlock(MachineBasicBlock *MBB) {
 /// up the dominator tree to destroy ancestors which are now done.
 void
 MachineCSE::ExitScopeIfDone(MachineDomTreeNode *Node,
-                DenseMap<MachineDomTreeNode*, unsigned> &OpenChildren,
-                DenseMap<MachineDomTreeNode*, MachineDomTreeNode*> &ParentMap) {
+                        DenseMap<MachineDomTreeNode*, unsigned> &OpenChildren) {
   if (OpenChildren[Node])
     return;
 
@@ -545,7 +544,7 @@ MachineCSE::ExitScopeIfDone(MachineDomTreeNode *Node,
   ExitScope(Node->getBlock());
 
   // Now traverse upwards to pop ancestors whose offsprings are all done.
-  while (MachineDomTreeNode *Parent = ParentMap[Node]) {
+  while (MachineDomTreeNode *Parent = Node->getIDom()) {
     unsigned Left = --OpenChildren[Parent];
     if (Left != 0)
       break;
@@ -557,7 +556,6 @@ MachineCSE::ExitScopeIfDone(MachineDomTreeNode *Node,
 bool MachineCSE::PerformCSE(MachineDomTreeNode *Node) {
   SmallVector<MachineDomTreeNode*, 32> Scopes;
   SmallVector<MachineDomTreeNode*, 8> WorkList;
-  DenseMap<MachineDomTreeNode*, MachineDomTreeNode*> ParentMap;
   DenseMap<MachineDomTreeNode*, unsigned> OpenChildren;
 
   CurrVN = 0;
@@ -572,7 +570,6 @@ bool MachineCSE::PerformCSE(MachineDomTreeNode *Node) {
     OpenChildren[Node] = NumChildren;
     for (unsigned i = 0; i != NumChildren; ++i) {
       MachineDomTreeNode *Child = Children[i];
-      ParentMap[Child] = Node;
       WorkList.push_back(Child);
     }
   } while (!WorkList.empty());
@@ -585,7 +582,7 @@ bool MachineCSE::PerformCSE(MachineDomTreeNode *Node) {
     EnterScope(MBB);
     Changed |= ProcessBlock(MBB);
     // If it's a leaf node, it's done. Traverse upwards to pop ancestors.
-    ExitScopeIfDone(Node, OpenChildren, ParentMap);
+    ExitScopeIfDone(Node, OpenChildren);
   }
 
   return Changed;
-- 
2.34.1