<div dir="ltr">Hi Alexy, Duncan,<div><br></div><div style>I've reapplied this, with Jakob's suggested fix from PR15320, in r175809. I'll keep my eye out for build breakage, but I think this should fix the issue.</div>
<div style><br></div><div style>Cheers,</div><div style>Lang.</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Thu, Feb 21, 2013 at 9:07 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"><div class="im"><div dir="ltr"><span style="font-family:arial,sans-serif;font-size:13px">Hi Alexy, Duncan,</span><div style="font-family:arial,sans-serif;font-size:13px">
<br></div><div style="font-family:arial,sans-serif;font-size:13px">Thanks for catching this. I've reverted it in r175765.</div>
<div style="font-family:arial,sans-serif;font-size:13px"><br></div><div style="font-family:arial,sans-serif;font-size:13px">The existing TransferDeadFlag code is broken - Targets are free to replace copies and subreg-to-reg instructions with instructions that define super-regs. In that case TransferDeadFlag will either crash, or (worse) may tag an unrelated earlier definition as dead. I'll track down whatever is wrong with this fix and re-apply.</div>
<div style="font-family:arial,sans-serif;font-size:13px"><br></div><div style="font-family:arial,sans-serif;font-size:13px">Cheers,</div><div style="font-family:arial,sans-serif;font-size:13px">Lang.</div><div style="font-family:arial,sans-serif;font-size:13px">
</div></div></div><div class="gmail_extra"><br><br><div class="gmail_quote"><div class="im">On Thu, Feb 21, 2013 at 4:22 AM, Duncan Sands <span dir="ltr"><<a href="mailto:baldrick@free.fr" target="_blank">baldrick@free.fr</a>></span> wrote:<br>
</div><div><div class="h5"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>On 21/02/13 12:21, Alexey Samsonov wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hi, Lang!<br>
<br>
I think this is causing <a href="http://llvm.org/bugs/show_bug.cgi?id=15320" target="_blank">http://llvm.org/bugs/show_bug.<u></u>cgi?id=15320</a>. Could you<br>
please take a look?<br>
</blockquote>
<br></div>
Vast numbers of dragonegg buildbots are showing a miscompilation, and this<br>
commit is in the blame list... So I also ask you to please take a look!<br>
<br>
Ciao, Duncan.<br>
<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>
<br>
<br>
On Thu, Feb 21, 2013 at 3:36 AM, Lang Hames <<a href="mailto:lhames@gmail.com" target="_blank">lhames@gmail.com</a><br></div><div><div>
<mailto:<a href="mailto:lhames@gmail.com" target="_blank">lhames@gmail.com</a>>> wrote:<br>
<br>
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-<u></u>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/<u></u>ExpandPostRAPseudos.cpp<br>
<br>
Modified: llvm/trunk/lib/CodeGen/<u></u>ExpandPostRAPseudos.cpp<br>
URL:<br>
<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-<u></u>project/llvm/trunk/lib/<u></u>CodeGen/ExpandPostRAPseudos.<u></u>cpp?rev=175688&r1=175687&r2=<u></u>175688&view=diff</a><br>
==============================<u></u>==============================<u></u>==================<br>
--- llvm/trunk/lib/CodeGen/<u></u>ExpandPostRAPseudos.cpp (original)<br>
+++ llvm/trunk/lib/CodeGen/<u></u>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(<u></u>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::<u></u>TransferDeadFlag(MachineInstr *MI, unsigned DstReg,<br>
- const TargetRegisterInfo *TRI) {<br>
- for (MachineBasicBlock::iterator MII =<br>
- prior(MachineBasicBlock::<u></u>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::<u></u>LowerSubregToReg(Mach<br>
}<br>
DEBUG(dbgs() << "subreg: eliminated!");<br>
} else {<br>
+ if (MI->getOperand(0).isDead()) {<br>
+ MI->setDesc(TII->get(<u></u>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(<u></u>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(<u></u>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(<u></u>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(<u></u>TargetOpcode::KILL));<br>
@@ -171,8 +161,6 @@ bool ExpandPostRA::LowerCopy(<u></u>MachineInst<br>
TII->copyPhysReg(*MI-><u></u>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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<br>
<br>
<br>
--<br>
Alexey Samsonov, MSK<br>
<br>
<br>
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