<div dir="ltr">Hi, Lang!<div><br></div><div style>I think this is causing <a href="http://llvm.org/bugs/show_bug.cgi?id=15320">http://llvm.org/bugs/show_bug.cgi?id=15320</a>. Could you please take a look?</div></div><div class="gmail_extra">
<br><br><div class="gmail_quote">On Thu, Feb 21, 2013 at 3:36 AM, Lang Hames <span dir="ltr"><<a href="mailto:lhames@gmail.com" target="_blank">lhames@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Author: lhames<br>
Date: Wed Feb 20 17:36:57 2013<br>
New Revision: 175688<br>
<br>
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=175688&view=rev" target="_blank">http://llvm.org/viewvc/llvm-project?rev=175688&view=rev</a><br>
Log:<br>
Kill of TransferDeadFlag - Dead copies and subreg-to-reg instructions should<br>
just be turned into kills on the spot.<br>
<br>
<br>
Modified:<br>
    llvm/trunk/lib/CodeGen/ExpandPostRAPseudos.cpp<br>
<br>
Modified: llvm/trunk/lib/CodeGen/ExpandPostRAPseudos.cpp<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/ExpandPostRAPseudos.cpp?rev=175688&r1=175687&r2=175688&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/ExpandPostRAPseudos.cpp?rev=175688&r1=175687&r2=175688&view=diff</a><br>

==============================================================================<br>
--- llvm/trunk/lib/CodeGen/ExpandPostRAPseudos.cpp (original)<br>
+++ llvm/trunk/lib/CodeGen/ExpandPostRAPseudos.cpp Wed Feb 20 17:36:57 2013<br>
@@ -49,8 +49,6 @@ private:<br>
   bool LowerSubregToReg(MachineInstr *MI);<br>
   bool LowerCopy(MachineInstr *MI);<br>
<br>
-  void TransferDeadFlag(MachineInstr *MI, unsigned DstReg,<br>
-                        const TargetRegisterInfo *TRI);<br>
   void TransferImplicitDefs(MachineInstr *MI);<br>
 };<br>
 } // end anonymous namespace<br>
@@ -61,21 +59,6 @@ char &llvm::ExpandPostRAPseudosID = Expa<br>
 INITIALIZE_PASS(ExpandPostRA, "postrapseudos",<br>
                 "Post-RA pseudo instruction expansion pass", false, false)<br>
<br>
-/// TransferDeadFlag - MI is a pseudo-instruction with DstReg dead,<br>
-/// and the lowered replacement instructions immediately precede it.<br>
-/// Mark the replacement instructions with the dead flag.<br>
-void<br>
-ExpandPostRA::TransferDeadFlag(MachineInstr *MI, unsigned DstReg,<br>
-                               const TargetRegisterInfo *TRI) {<br>
-  for (MachineBasicBlock::iterator MII =<br>
-        prior(MachineBasicBlock::iterator(MI)); ; --MII) {<br>
-    if (MII->addRegisterDead(DstReg, TRI))<br>
-      break;<br>
-    assert(MII != MI->getParent()->begin() &&<br>
-           "copyPhysReg output doesn't reference destination register!");<br>
-  }<br>
-}<br>
-<br>
 /// TransferImplicitDefs - MI is a pseudo-instruction, and the lowered<br>
 /// replacement instructions immediately precede it.  Copy any implicit-def<br>
 /// operands from MI to the replacement instruction.<br>
@@ -128,17 +111,17 @@ bool ExpandPostRA::LowerSubregToReg(Mach<br>
     }<br>
     DEBUG(dbgs() << "subreg: eliminated!");<br>
   } else {<br>
+    if (MI->getOperand(0).isDead()) {<br>
+      MI->setDesc(TII->get(TargetOpcode::KILL));<br>
+      DEBUG(dbgs() << "subreg: replaced by: " << *MI);<br>
+      return true;<br>
+    }<br>
     TII->copyPhysReg(*MBB, MI, MI->getDebugLoc(), DstSubReg, InsReg,<br>
                      MI->getOperand(2).isKill());<br>
-<br>
     // Implicitly define DstReg for subsequent uses.<br>
     MachineBasicBlock::iterator CopyMI = MI;<br>
     --CopyMI;<br>
     CopyMI->addRegisterDefined(DstReg);<br>
-<br>
-    // Transfer the kill/dead flags, if needed.<br>
-    if (MI->getOperand(0).isDead())<br>
-      TransferDeadFlag(MI, DstSubReg, TRI);<br>
     DEBUG(dbgs() << "subreg: " << *CopyMI);<br>
   }<br>
<br>
@@ -151,11 +134,18 @@ bool ExpandPostRA::LowerCopy(MachineInst<br>
   MachineOperand &DstMO = MI->getOperand(0);<br>
   MachineOperand &SrcMO = MI->getOperand(1);<br>
<br>
+  if (DstMO.isDead()) {<br>
+    DEBUG(dbgs() << "dead copy: " << *MI);<br>
+    MI->setDesc(TII->get(TargetOpcode::KILL));<br>
+    DEBUG(dbgs() << "replaced by: " << *MI);<br>
+    return true;<br>
+  }<br>
+<br>
   if (SrcMO.getReg() == DstMO.getReg()) {<br>
     DEBUG(dbgs() << "identity copy: " << *MI);<br>
     // No need to insert an identity copy instruction, but replace with a KILL<br>
     // if liveness is changed.<br>
-    if (DstMO.isDead() || SrcMO.isUndef() || MI->getNumOperands() > 2) {<br>
+    if (SrcMO.isUndef() || MI->getNumOperands() > 2) {<br>
       // We must make sure the super-register gets killed. Replace the<br>
       // instruction with KILL.<br>
       MI->setDesc(TII->get(TargetOpcode::KILL));<br>
@@ -171,8 +161,6 @@ bool ExpandPostRA::LowerCopy(MachineInst<br>
   TII->copyPhysReg(*MI->getParent(), MI, MI->getDebugLoc(),<br>
                    DstMO.getReg(), SrcMO.getReg(), SrcMO.isKill());<br>
<br>
-  if (DstMO.isDead())<br>
-    TransferDeadFlag(MI, DstMO.getReg(), TRI);<br>
   if (MI->getNumOperands() > 2)<br>
     TransferImplicitDefs(MI);<br>
   DEBUG({<br>
<br>
<br>
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</blockquote></div><br><br clear="all"><div><br></div>-- <br><div>Alexey Samsonov, MSK</div>
</div>