[llvm-commits] [llvm] r107949 - /llvm/trunk/lib/CodeGen/VirtRegRewriter.cpp

[Jakob Stoklund Olesen]

Author: stoklund
Date: Thu Jul  8 20:27:19 2010
New Revision: 107949

URL: http://llvm.org/viewvc/llvm-project?rev=107949&view=rev
Log:
Handle COPY in VirtRegRewriter.

Modified:
    llvm/trunk/lib/CodeGen/VirtRegRewriter.cpp

Modified: llvm/trunk/lib/CodeGen/VirtRegRewriter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/VirtRegRewriter.cpp?rev=107949&r1=107948&r2=107949&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/VirtRegRewriter.cpp (original)
+++ llvm/trunk/lib/CodeGen/VirtRegRewriter.cpp Thu Jul  8 20:27:19 2010
@@ -2443,6 +2443,24 @@
         // Also check if it's copying from an "undef", if so, we can't
         // eliminate this or else the undef marker is lost and it will
         // confuses the scavenger. This is extremely rare.
+        if (MI.isIdentityCopy() && !MI.getOperand(1).isUndef() &&
+            MI.getNumOperands() == 2) {
+          ++NumDCE;
+          DEBUG(dbgs() << "Removing now-noop copy: " << MI);
+          SmallVector<unsigned, 2> KillRegs;
+          InvalidateKills(MI, TRI, RegKills, KillOps, &KillRegs);
+          if (MO.isDead() && !KillRegs.empty()) {
+            // Source register or an implicit super/sub-register use is killed.
+            assert(TRI->regsOverlap(KillRegs[0], MI.getOperand(0).getReg()));
+            // Last def is now dead.
+            TransferDeadness(MI.getOperand(1).getReg(), RegKills, KillOps);
+          }
+          VRM->RemoveMachineInstrFromMaps(&MI);
+          MBB->erase(&MI);
+          Erased = true;
+          Spills.disallowClobberPhysReg(VirtReg);
+          goto ProcessNextInst;
+        }
         unsigned Src, Dst, SrcSR, DstSR;
         if (TII->isMoveInstr(MI, Src, Dst, SrcSR, DstSR) &&
             Src == Dst && SrcSR == DstSR &&
@@ -2532,6 +2550,16 @@
 
         // Check to see if this is a noop copy.  If so, eliminate the
         // instruction before considering the dest reg to be changed.
+        if (MI.isIdentityCopy()) {
+          ++NumDCE;
+          DEBUG(dbgs() << "Removing now-noop copy: " << MI);
+          InvalidateKills(MI, TRI, RegKills, KillOps);
+          VRM->RemoveMachineInstrFromMaps(&MI);
+          MBB->erase(&MI);
+          Erased = true;
+          UpdateKills(*LastStore, TRI, RegKills, KillOps);
+          goto ProcessNextInst;
+        }
         {
           unsigned Src, Dst, SrcSR, DstSR;
           if (TII->isMoveInstr(MI, Src, Dst, SrcSR, DstSR) &&