X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FMachineCSE.cpp;h=35ba7ff35e6f201a670e11bc2adf2812b86d075d;hb=bf329b3414bbc24efb6d44952a7cbf66c83bcca1;hp=56cea4e599ce289f03cad666a5cfabf53c29ef96;hpb=39834da697e5a6d0198a6a802133ce351c871904;p=oota-llvm.git

diff --git a/lib/CodeGen/MachineCSE.cpp b/lib/CodeGen/MachineCSE.cpp
index 56cea4e599c..35ba7ff35e6 100644
--- a/lib/CodeGen/MachineCSE.cpp
+++ b/lib/CodeGen/MachineCSE.cpp
@@ -15,17 +15,17 @@
 
 #define DEBUG_TYPE "machine-cse"
 #include "llvm/CodeGen/Passes.h"
-#include "llvm/CodeGen/MachineDominators.h"
-#include "llvm/CodeGen/MachineInstr.h"
-#include "llvm/CodeGen/MachineRegisterInfo.h"
-#include "llvm/Analysis/AliasAnalysis.h"
-#include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/ScopedHashTable.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/CodeGen/MachineDominators.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/RecyclingAllocator.h"
+#include "llvm/Target/TargetInstrInfo.h"
 using namespace llvm;
 
 STATISTIC(NumCoalesces, "Number of copies coalesced");
@@ -84,11 +84,11 @@ namespace {
     bool hasLivePhysRegDefUses(const MachineInstr *MI,
                                const MachineBasicBlock *MBB,
                                SmallSet<unsigned,8> &PhysRefs,
-                               SmallVector<unsigned,2> &PhysDefs,
+                               SmallVectorImpl<unsigned> &PhysDefs,
                                bool &PhysUseDef) const;
     bool PhysRegDefsReach(MachineInstr *CSMI, MachineInstr *MI,
                           SmallSet<unsigned,8> &PhysRefs,
-                          SmallVector<unsigned,2> &PhysDefs,
+                          SmallVectorImpl<unsigned> &PhysDefs,
                           bool &NonLocal) const;
     bool isCSECandidate(MachineInstr *MI);
     bool isProfitableToCSE(unsigned CSReg, unsigned Reg,
@@ -131,9 +131,24 @@ bool MachineCSE::PerformTrivialCoalescing(MachineInstr *MI,
     unsigned SrcReg = DefMI->getOperand(1).getReg();
     if (!TargetRegisterInfo::isVirtualRegister(SrcReg))
       continue;
-    if (DefMI->getOperand(0).getSubReg() || DefMI->getOperand(1).getSubReg())
+    if (DefMI->getOperand(0).getSubReg())
+      continue;
+    // FIXME: We should trivially coalesce subregister copies to expose CSE
+    // opportunities on instructions with truncated operands (see
+    // cse-add-with-overflow.ll). This can be done here as follows:
+    // if (SrcSubReg)
+    //  RC = TRI->getMatchingSuperRegClass(MRI->getRegClass(SrcReg), RC,
+    //                                     SrcSubReg);
+    // MO.substVirtReg(SrcReg, SrcSubReg, *TRI);
+    //
+    // The 2-addr pass has been updated to handle coalesced subregs. However,
+    // some machine-specific code still can't handle it.
+    // To handle it properly we also need a way find a constrained subregister
+    // class given a super-reg class and subreg index.
+    if (DefMI->getOperand(1).getSubReg())
       continue;
-    if (!MRI->constrainRegClass(SrcReg, MRI->getRegClass(Reg)))
+    const TargetRegisterClass *RC = MRI->getRegClass(Reg);
+    if (!MRI->constrainRegClass(SrcReg, RC))
       continue;
     DEBUG(dbgs() << "Coalescing: " << *DefMI);
     DEBUG(dbgs() << "***     to: " << *MI);
@@ -193,7 +208,7 @@ MachineCSE::isPhysDefTriviallyDead(unsigned Reg,
 bool MachineCSE::hasLivePhysRegDefUses(const MachineInstr *MI,
                                        const MachineBasicBlock *MBB,
                                        SmallSet<unsigned,8> &PhysRefs,
-                                       SmallVector<unsigned,2> &PhysDefs,
+                                       SmallVectorImpl<unsigned> &PhysDefs,
                                        bool &PhysUseDef) const{
   // First, add all uses to PhysRefs.
   for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
@@ -244,7 +259,7 @@ bool MachineCSE::hasLivePhysRegDefUses(const MachineInstr *MI,
 
 bool MachineCSE::PhysRegDefsReach(MachineInstr *CSMI, MachineInstr *MI,
                                   SmallSet<unsigned,8> &PhysRefs,
-                                  SmallVector<unsigned,2> &PhysDefs,
+                                  SmallVectorImpl<unsigned> &PhysDefs,
                                   bool &NonLocal) const {
   // For now conservatively returns false if the common subexpression is
   // not in the same basic block as the given instruction. The only exception
@@ -513,7 +528,7 @@ bool MachineCSE::ProcessBlock(MachineBasicBlock *MBB) {
     bool DoCSE = true;
     unsigned NumDefs = MI->getDesc().getNumDefs() +
                        MI->getDesc().getNumImplicitDefs();
-    
+
     for (unsigned i = 0, e = MI->getNumOperands(); NumDefs && i != e; ++i) {
       MachineOperand &MO = MI->getOperand(i);
       if (!MO.isReg() || !MO.isDef())