Handle COPY in VirtRegRewriter.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107949 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/VirtRegRewriter.cpp b/lib/CodeGen/VirtRegRewriter.cpp
index 15142c0..d8f0249 100644
--- a/lib/CodeGen/VirtRegRewriter.cpp
+++ b/lib/CodeGen/VirtRegRewriter.cpp
@@ -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) &&