From 714973e459d6611dd3e67f77968aba55528664b4 Mon Sep 17 00:00:00 2001
From: Andrew Trick <atrick@apple.com>
Date: Tue, 9 Oct 2012 23:44:23 +0000
Subject: misched: Remove LoopDependencies heuristic.

This wasn't contributing anything significant to postRA heuristics except compile time (by my measurements) and will be replaced by a more general heuristic for cross-region dependencies within the scheduler itself.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165563 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/CodeGen/ScheduleDAGInstrs.h | 70 --------------------------------
 1 file changed, 70 deletions(-)

(limited to 'include/llvm/CodeGen')

diff --git a/include/llvm/CodeGen/ScheduleDAGInstrs.h b/include/llvm/CodeGen/ScheduleDAGInstrs.h
index d13ee84257..4d8f7a3768 100644
--- a/include/llvm/CodeGen/ScheduleDAGInstrs.h
+++ b/include/llvm/CodeGen/ScheduleDAGInstrs.h
@@ -31,72 +31,6 @@ namespace llvm {
   class LiveIntervals;
   class RegPressureTracker;
 
-  /// LoopDependencies - This class analyzes loop-oriented register
-  /// dependencies, which are used to guide scheduling decisions.
-  /// For example, loop induction variable increments should be
-  /// scheduled as soon as possible after the variable's last use.
-  ///
-  class LoopDependencies {
-    const MachineDominatorTree &MDT;
-
-  public:
-    typedef std::map<unsigned, std::pair<const MachineOperand *, unsigned> >
-      LoopDeps;
-    LoopDeps Deps;
-
-    LoopDependencies(const MachineDominatorTree &mdt) : MDT(mdt) {}
-
-    /// VisitLoop - Clear out any previous state and analyze the given loop.
-    ///
-    void VisitLoop(const MachineLoop *Loop) {
-      assert(Deps.empty() && "stale loop dependencies");
-
-      MachineBasicBlock *Header = Loop->getHeader();
-      SmallSet<unsigned, 8> LoopLiveIns;
-      for (MachineBasicBlock::livein_iterator LI = Header->livein_begin(),
-           LE = Header->livein_end(); LI != LE; ++LI)
-        LoopLiveIns.insert(*LI);
-
-      const MachineDomTreeNode *Node = MDT.getNode(Header);
-      const MachineBasicBlock *MBB = Node->getBlock();
-      assert(Loop->contains(MBB) &&
-             "Loop does not contain header!");
-      VisitRegion(Node, MBB, Loop, LoopLiveIns);
-    }
-
-  private:
-    void VisitRegion(const MachineDomTreeNode *Node,
-                     const MachineBasicBlock *MBB,
-                     const MachineLoop *Loop,
-                     const SmallSet<unsigned, 8> &LoopLiveIns) {
-      unsigned Count = 0;
-      for (MachineBasicBlock::const_iterator I = MBB->begin(), E = MBB->end();
-           I != E; ++I) {
-        const MachineInstr *MI = I;
-        if (MI->isDebugValue())
-          continue;
-        for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
-          const MachineOperand &MO = MI->getOperand(i);
-          if (!MO.isReg() || !MO.isUse())
-            continue;
-          unsigned MOReg = MO.getReg();
-          if (LoopLiveIns.count(MOReg))
-            Deps.insert(std::make_pair(MOReg, std::make_pair(&MO, Count)));
-        }
-        ++Count; // Not every iteration due to dbg_value above.
-      }
-
-      const std::vector<MachineDomTreeNode*> &Children = Node->getChildren();
-      for (std::vector<MachineDomTreeNode*>::const_iterator I =
-           Children.begin(), E = Children.end(); I != E; ++I) {
-        const MachineDomTreeNode *ChildNode = *I;
-        MachineBasicBlock *ChildBlock = ChildNode->getBlock();
-        if (Loop->contains(ChildBlock))
-          VisitRegion(ChildNode, ChildBlock, Loop, LoopLiveIns);
-      }
-    }
-  };
-
   /// An individual mapping from virtual register number to SUnit.
   struct VReg2SUnit {
     unsigned VirtReg;
@@ -236,10 +170,6 @@ namespace llvm {
     /// to minimize construction/destruction.
     std::vector<SUnit *> PendingLoads;
 
-    /// LoopRegs - Track which registers are used for loop-carried dependencies.
-    ///
-    LoopDependencies LoopRegs;
-
     /// DbgValues - Remember instruction that precedes DBG_VALUE.
     /// These are generated by buildSchedGraph but persist so they can be
     /// referenced when emitting the final schedule.
-- 
cgit v1.2.3-70-g09d2