X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FMachineCopyPropagation.cpp;h=e41d3eee216a7c54901cf627bf1265213733f390;hb=34fa5640b805e6bc7a8259e181eed64051c09b4e;hp=1673498f1789e6c4c9b0204a84cee718830d03ae;hpb=388ffa7f663393ed91b1a07237d1c34710daeaa1;p=oota-llvm.git

diff --git a/lib/CodeGen/MachineCopyPropagation.cpp b/lib/CodeGen/MachineCopyPropagation.cpp
index 1673498f178..e41d3eee216 100644
--- a/lib/CodeGen/MachineCopyPropagation.cpp
+++ b/lib/CodeGen/MachineCopyPropagation.cpp
@@ -13,18 +13,19 @@
 
 #define DEBUG_TYPE "codegen-cp"
 #include "llvm/CodeGen/Passes.h"
-#include "llvm/Pass.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
-#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Pass.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/SetVector.h"
-#include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/Statistic.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetRegisterInfo.h"
 using namespace llvm;
 
 STATISTIC(NumDeletes, "Number of dead copies deleted");
@@ -32,6 +33,7 @@ STATISTIC(NumDeletes, "Number of dead copies deleted");
 namespace {
   class MachineCopyPropagation : public MachineFunctionPass {
     const TargetRegisterInfo *TRI;
+    const TargetInstrInfo *TII;
     MachineRegisterInfo *MRI;
 
   public:
@@ -50,6 +52,7 @@ namespace {
                                  SourceMap &SrcMap,
                                  DenseMap<unsigned, MachineInstr*> &AvailCopyMap);
     bool CopyPropagateBlock(MachineBasicBlock &MBB);
+    void removeCopy(MachineInstr *MI);
   };
 }
 char MachineCopyPropagation::ID = 0;
@@ -123,12 +126,21 @@ static bool isNopCopy(MachineInstr *CopyMI, unsigned Def, unsigned Src,
   return false;
 }
 
+// Remove MI from the function because it has been determined it is dead.
+// Turn it into a noop KILL instruction as opposed to removing it to
+// maintain imp-use/imp-def chains.
+void MachineCopyPropagation::removeCopy(MachineInstr *MI) {
+  MI->setDesc(TII->get(TargetOpcode::KILL));
+}
+
 bool MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
   SmallSetVector<MachineInstr*, 8> MaybeDeadCopies;  // Candidates for deletion
   DenseMap<unsigned, MachineInstr*> AvailCopyMap;    // Def -> available copies map
   DenseMap<unsigned, MachineInstr*> CopyMap;         // Def -> copies map
   SourceMap SrcMap; // Src -> Def map
 
+  DEBUG(dbgs() << "MCP: CopyPropagateBlock " << MBB.getName() << "\n");
+
   bool Changed = false;
   for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end(); I != E; ) {
     MachineInstr *MI = &*I;
@@ -163,12 +175,14 @@ bool MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
           // CALL
           // %RAX<def> = COPY %RSP
 
+          DEBUG(dbgs() << "MCP: copy is a NOP, removing: "; MI->dump());
+
           // Clear any kills of Def between CopyMI and MI. This extends the
           // live range.
           for (MachineBasicBlock::iterator I = CopyMI, E = MI; I != E; ++I)
             I->clearRegisterKills(Def, TRI);
 
-          MI->eraseFromParent();
+          removeCopy(MI);
           Changed = true;
           ++NumDeletes;
           continue;
@@ -178,10 +192,14 @@ bool MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
       // If Src is defined by a previous copy, it cannot be eliminated.
       for (MCRegAliasIterator AI(Src, TRI, true); AI.isValid(); ++AI) {
         CI = CopyMap.find(*AI);
-        if (CI != CopyMap.end())
+        if (CI != CopyMap.end()) {
+          DEBUG(dbgs() << "MCP: Copy is no longer dead: "; CI->second->dump());
           MaybeDeadCopies.remove(CI->second);
+        }
       }
 
+      DEBUG(dbgs() << "MCP: Copy is a deletion candidate: "; MI->dump());
+
       // Copy is now a candidate for deletion.
       MaybeDeadCopies.insert(MI);
 
@@ -200,9 +218,8 @@ bool MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
         CopyMap.erase(*AI);
         AvailCopyMap.erase(*AI);
       }
-      CopyMap[Def] = MI;
-      AvailCopyMap[Def] = MI;
-      for (MCSubRegIterator SR(Def, TRI); SR.isValid(); ++SR) {
+      for (MCSubRegIterator SR(Def, TRI, /*IncludeSelf=*/true); SR.isValid();
+           ++SR) {
         CopyMap[*SR] = MI;
         AvailCopyMap[*SR] = MI;
       }
@@ -243,8 +260,10 @@ bool MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
       // for elimination.
       for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI) {
         DenseMap<unsigned, MachineInstr*>::iterator CI = CopyMap.find(*AI);
-        if (CI != CopyMap.end())
+        if (CI != CopyMap.end()) {
+          DEBUG(dbgs() << "MCP: Copy is used - not dead: "; CI->second->dump());
           MaybeDeadCopies.remove(CI->second);
+        }
       }
     }
 
@@ -261,7 +280,9 @@ bool MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
         unsigned Reg = (*DI)->getOperand(0).getReg();
         if (MRI->isReserved(Reg) || !MaskMO.clobbersPhysReg(Reg))
           continue;
-        (*DI)->eraseFromParent();
+        DEBUG(dbgs() << "MCP: Removing copy due to regmask clobbering: ";
+              (*DI)->dump());
+        removeCopy(*DI);
         Changed = true;
         ++NumDeletes;
       }
@@ -297,7 +318,7 @@ bool MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
            DI = MaybeDeadCopies.begin(), DE = MaybeDeadCopies.end();
          DI != DE; ++DI) {
       if (!MRI->isReserved((*DI)->getOperand(0).getReg())) {
-        (*DI)->eraseFromParent();
+        removeCopy(*DI);
         Changed = true;
         ++NumDeletes;
       }
@@ -311,6 +332,7 @@ bool MachineCopyPropagation::runOnMachineFunction(MachineFunction &MF) {
   bool Changed = false;
 
   TRI = MF.getTarget().getRegisterInfo();
+  TII = MF.getTarget().getInstrInfo();
   MRI = &MF.getRegInfo();
 
   for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I)