Revert "Reapply 91184 with fixes and an addition to the testcase to cover the

[oota-llvm.git] / lib / CodeGen / PHIElimination.h

diff --git a/lib/CodeGen/PHIElimination.h b/lib/CodeGen/PHIElimination.h
index 26a37316eb8b2d36fdde66b1cd866413f8488718..b0b71ce2bc5ed7a4620a06da179bbd42902f0712 100644 (file)
--- a/lib/CodeGen/PHIElimination.h
+++ b/lib/CodeGen/PHIElimination.h
@@ -10,6 +10,8 @@
 #ifndef LLVM_CODEGEN_PHIELIMINATION_HPP
 #define LLVM_CODEGEN_PHIELIMINATION_HPP
 
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/Target/TargetInstrInfo.h"
@@ -21,8 +23,17 @@ namespace llvm {
   /// Lower PHI instructions to copies.  
   class PHIElimination : public MachineFunctionPass {
     MachineRegisterInfo  *MRI; // Machine register information
+  private:
+
+    typedef SmallSet<MachineBasicBlock*, 4> PHIKillList;
+    typedef DenseMap<unsigned, PHIKillList> PHIKillMap;
+    typedef DenseMap<unsigned, MachineBasicBlock*> PHIDefMap;
 
   public:
+
+    typedef PHIKillList::iterator phi_kill_iterator;
+    typedef PHIKillList::const_iterator const_phi_kill_iterator;
+
     static char ID; // Pass identification, replacement for typeid
     PHIElimination() : MachineFunctionPass(&ID) {}
 
@@ -30,6 +41,38 @@ namespace llvm {
     
     virtual void getAnalysisUsage(AnalysisUsage &AU) const;
 
+    /// Return true if the given vreg was defined by a PHI intsr prior to
+    /// lowering.
+    bool hasPHIDef(unsigned vreg) const {
+      return PHIDefs.count(vreg);
+    }
+
+    /// Returns the block in which the PHI instruction which defined the
+    /// given vreg used to reside. 
+    MachineBasicBlock* getPHIDefBlock(unsigned vreg) {
+      PHIDefMap::iterator phiDefItr = PHIDefs.find(vreg);
+      assert(phiDefItr != PHIDefs.end() && "vreg has no phi-def.");
+      return phiDefItr->second;
+    }
+
+    /// Returns true if the given vreg was killed by a PHI instr.
+    bool hasPHIKills(unsigned vreg) const {
+      return PHIKills.count(vreg);
+    }
+
+    /// Returns an iterator over the BasicBlocks which contained PHI
+    /// kills of this register prior to lowering.
+    phi_kill_iterator phiKillsBegin(unsigned vreg) {
+      PHIKillMap::iterator phiKillItr = PHIKills.find(vreg);
+      assert(phiKillItr != PHIKills.end() && "vreg has no phi-kills.");
+      return phiKillItr->second.begin();
+    } 
+    phi_kill_iterator phiKillsEnd(unsigned vreg) {
+      PHIKillMap::iterator phiKillItr = PHIKills.find(vreg);
+      assert(phiKillItr != PHIKills.end() && "vreg has no phi-kills.");
+      return phiKillItr->second.end();
+    }
+
   private:
     /// EliminatePHINodes - Eliminate phi nodes by inserting copy instructions
     /// in predecessor basic blocks.
@@ -46,11 +89,22 @@ namespace llvm {
     ///
     void analyzePHINodes(const MachineFunction& Fn);
 
-    // FindCopyInsertPoint - Find a safe place in MBB to insert a copy from
-    // SrcReg.  This needs to be after any def or uses of SrcReg, but before
-    // any subsequent point where control flow might jump out of the basic
-    // block.
+    /// Split critical edges where necessary for good coalescer performance.
+    bool SplitPHIEdges(MachineFunction &MF, MachineBasicBlock &MBB,
+                       LiveVariables &LV);
+
+    /// SplitCriticalEdge - Split a critical edge from A to B by
+    /// inserting a new MBB. Update branches in A and PHI instructions
+    /// in B. Return the new block.
+    MachineBasicBlock *SplitCriticalEdge(MachineBasicBlock *A,
+                                         MachineBasicBlock *B);
+
+    /// FindCopyInsertPoint - Find a safe place in MBB to insert a copy from
+    /// SrcReg when following the CFG edge to SuccMBB. This needs to be after
+    /// any def of SrcReg, but before any subsequent point where control flow
+    /// might jump out of the basic block.
     MachineBasicBlock::iterator FindCopyInsertPoint(MachineBasicBlock &MBB,
+                                                    MachineBasicBlock &SuccMBB,
                                                     unsigned SrcReg);
 
     // SkipPHIsAndLabels - Copies need to be inserted after phi nodes and
@@ -70,6 +124,8 @@ namespace llvm {
     typedef std::map<BBVRegPair, unsigned> VRegPHIUse;
 
     VRegPHIUse VRegPHIUseCount;
+    PHIDefMap PHIDefs;
+    PHIKillMap PHIKills;
 
     // Defs of PHI sources which are implicit_def.
     SmallPtrSet<MachineInstr*, 4> ImpDefs;
@@ -77,4 +133,4 @@ namespace llvm {
 
 }
 
-#endif /* PHIELIMINATION_H */
+#endif /* LLVM_CODEGEN_PHIELIMINATION_HPP */