[llvm-commits] [llvm] r102510 - in /llvm/trunk/lib/CodeGen: SimpleRegisterCoalescing.cpp SimpleRegisterCoalescing.h
Jakob Stoklund Olesen
stoklund at 2pi.dk
Wed Apr 28 11:28:40 PDT 2010
Author: stoklund
Date: Wed Apr 28 13:28:39 2010
New Revision: 102510
URL: http://llvm.org/viewvc/llvm-project?rev=102510&view=rev
Log:
Recompute kill flags from live intervals after coalescing instead of trying to
update them. Computing kill flags is notoriously difficult, and the coalescer
would get it wrong sometimes, and it would completely skip physical registers.
Now we simply remove kill flags based on the live intervals after coalescing.
This is a few percent slower, but now we get correct kill flags for physical
registers after coalescing.
Modified:
llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp
llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.h
Modified: llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp?rev=102510&r1=102509&r2=102510&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp (original)
+++ llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp Wed Apr 28 13:28:39 2010
@@ -236,7 +236,7 @@
// If the copy instruction was killing the destination register before the
// merge, find the last use and trim the live range. That will also add the
// isKill marker.
- if (CopyMI->killsRegister(IntA.reg))
+ if (ALR->valno->isKill(CopyIdx))
TrimLiveIntervalToLastUse(CopyUseIdx, CopyMI->getParent(), IntA, ALR);
++numExtends;
@@ -709,7 +709,7 @@
// kill.
bool checkForDeadDef = false;
MachineBasicBlock *MBB = CopyMI->getParent();
- if (CopyMI->killsRegister(SrcInt.reg))
+ if (SrcLR->valno->isKill(DefIdx))
if (!TrimLiveIntervalToLastUse(CopyIdx, MBB, SrcInt, SrcLR)) {
checkForDeadDef = true;
}
@@ -837,9 +837,6 @@
assert(OldSubIdx < SubIdx && "Conflicting sub-register index!");
else if (SubIdx)
O.setSubReg(SubIdx);
- // Remove would-be duplicated kill marker.
- if (O.isKill() && UseMI->killsRegister(DstReg))
- O.setIsKill(false);
O.setReg(DstReg);
// After updating the operand, check if the machine instruction has
@@ -866,38 +863,6 @@
}
}
-/// RemoveUnnecessaryKills - Remove kill markers that are no longer accurate
-/// due to live range lengthening as the result of coalescing.
-void SimpleRegisterCoalescing::RemoveUnnecessaryKills(unsigned Reg,
- LiveInterval &LI) {
- for (MachineRegisterInfo::use_iterator UI = mri_->use_begin(Reg),
- UE = mri_->use_end(); UI != UE; ++UI) {
- MachineOperand &UseMO = UI.getOperand();
- if (!UseMO.isKill())
- continue;
- MachineInstr *UseMI = UseMO.getParent();
- SlotIndex UseIdx =
- li_->getInstructionIndex(UseMI).getUseIndex();
- const LiveRange *LR = LI.getLiveRangeContaining(UseIdx);
- if (!LR ||
- (!LR->valno->isKill(UseIdx.getDefIndex()) &&
- LR->valno->def != UseIdx.getDefIndex())) {
- // Interesting problem. After coalescing reg1027's def and kill are both
- // at the same point: %reg1027,0.000000e+00 = [56,814:0) 0 at 70-(814)
- //
- // bb5:
- // 60 %reg1027<def> = t2MOVr %reg1027, 14, %reg0, %reg0
- // 68 %reg1027<def> = t2LDRi12 %reg1027<kill>, 8, 14, %reg0
- // 76 t2CMPzri %reg1038<kill,undef>, 0, 14, %reg0, %CPSR<imp-def>
- // 84 %reg1027<def> = t2MOVr %reg1027, 14, %reg0, %reg0
- // 96 t2Bcc mbb<bb5,0x2030910>, 1, %CPSR<kill>
- //
- // Do not remove the kill marker on t2LDRi12.
- UseMO.setIsKill(false);
- }
- }
-}
-
/// removeIntervalIfEmpty - Check if the live interval of a physical register
/// is empty, if so remove it and also remove the empty intervals of its
/// sub-registers. Return true if live interval is removed.
@@ -1811,12 +1776,6 @@
// Remember to delete the copy instruction.
JoinedCopies.insert(CopyMI);
- // Some live range has been lengthened due to colaescing, eliminate the
- // unnecessary kills.
- RemoveUnnecessaryKills(SrcReg, *ResDstInt);
- if (TargetRegisterInfo::isVirtualRegister(DstReg))
- RemoveUnnecessaryKills(DstReg, *ResDstInt);
-
UpdateRegDefsUses(SrcReg, DstReg, SubIdx);
// If we have extended the live range of a physical register, make sure we
@@ -2825,8 +2784,25 @@
li_->RemoveMachineInstrFromMaps(MI);
mii = mbbi->erase(mii);
++numPeep;
- } else {
- ++mii;
+ continue;
+ }
+
+ ++mii;
+
+ // Check for now unnecessary kill flags.
+ if (li_->isNotInMIMap(MI)) continue;
+ SlotIndex UseIdx = li_->getInstructionIndex(MI).getUseIndex();
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = MI->getOperand(i);
+ if (!MO.isReg() || !MO.isKill()) continue;
+ unsigned reg = MO.getReg();
+ if (!reg || !li_->hasInterval(reg)) continue;
+ LiveInterval &LI = li_->getInterval(reg);
+ const LiveRange *LR = LI.getLiveRangeContaining(UseIdx);
+ if (!LR ||
+ (!LR->valno->isKill(UseIdx.getDefIndex()) &&
+ LR->valno->def != UseIdx.getDefIndex()))
+ MO.setIsKill(false);
}
}
}
Modified: llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.h?rev=102510&r1=102509&r2=102510&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.h (original)
+++ llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.h Wed Apr 28 13:28:39 2010
@@ -223,10 +223,6 @@
/// subregister.
void UpdateRegDefsUses(unsigned SrcReg, unsigned DstReg, unsigned SubIdx);
- /// RemoveUnnecessaryKills - Remove kill markers that are no longer accurate
- /// due to live range lengthening as the result of coalescing.
- void RemoveUnnecessaryKills(unsigned Reg, LiveInterval &LI);
-
/// ShortenDeadCopyLiveRange - Shorten a live range defined by a dead copy.
/// Return true if live interval is removed.
bool ShortenDeadCopyLiveRange(LiveInterval &li, MachineInstr *CopyMI);
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