When a load operand is promoted to an extload, replace other uses with uses of extloa...

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

diff --git a/lib/CodeGen/PHIElimination.h b/lib/CodeGen/PHIElimination.h
index 26a37316eb8b2d36fdde66b1cd866413f8488718..7dedf0318a8a67ca296044054a3d12bb437892cf 100644 (file)
--- a/lib/CodeGen/PHIElimination.h
+++ b/lib/CodeGen/PHIElimination.h
@@ -10,14 +10,15 @@
 #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"
-
-#include <map>
+#include "llvm/CodeGen/MachineRegisterInfo.h"
 
 namespace llvm {
-
+  class LiveVariables;
+  
   /// Lower PHI instructions to copies.  
   class PHIElimination : public MachineFunctionPass {
     MachineRegisterInfo  *MRI; // Machine register information
@@ -46,35 +47,67 @@ 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
     // also after any exception handling labels: in landing pads execution
     // starts at the label, so any copies placed before it won't be executed!
+    // We also deal with DBG_VALUEs, which are a bit tricky:
+    //  PHI
+    //  DBG_VALUE
+    //  LABEL
+    // Here the DBG_VALUE needs to be skipped, and if it refers to a PHI it
+    // needs to be annulled or, better, moved to follow the label, as well.
+    //  PHI
+    //  DBG_VALUE
+    //  no label
+    // Here it is not a good idea to skip the DBG_VALUE.
+    // FIXME: For now we skip and annul all DBG_VALUEs, maximally simple and
+    // maximally stupid.
     MachineBasicBlock::iterator SkipPHIsAndLabels(MachineBasicBlock &MBB,
                                                 MachineBasicBlock::iterator I) {
       // Rather than assuming that EH labels come before other kinds of labels,
       // just skip all labels.
-      while (I != MBB.end() &&
-             (I->getOpcode() == TargetInstrInfo::PHI || I->isLabel()))
+      while (I != MBB.end() && 
+             (I->isPHI() || I->isLabel() || I->isDebugValue())) {
+        if (I->isDebugValue() && I->getNumOperands()==3 && 
+            I->getOperand(0).isReg())
+          I->getOperand(0).setReg(0U);
         ++I;
+      }
       return I;
     }
 
-    typedef std::pair<const MachineBasicBlock*, unsigned> BBVRegPair;
-    typedef std::map<BBVRegPair, unsigned> VRegPHIUse;
+    typedef std::pair<unsigned, unsigned> BBVRegPair;
+    typedef DenseMap<BBVRegPair, unsigned> VRegPHIUse;
 
     VRegPHIUse VRegPHIUseCount;
 
     // Defs of PHI sources which are implicit_def.
     SmallPtrSet<MachineInstr*, 4> ImpDefs;
+
+    // Map reusable lowered PHI node -> incoming join register.
+    typedef DenseMap<MachineInstr*, unsigned,
+                     MachineInstrExpressionTrait> LoweredPHIMap;
+    LoweredPHIMap LoweredPHIs;
   };
 
 }
 
-#endif /* PHIELIMINATION_H */
+#endif /* LLVM_CODEGEN_PHIELIMINATION_HPP */