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Eliminate some extra hash table lookups. 

llvm-svn: 123115
This commit is contained in:
Cameron Zwarich 2011-01-09 10:54:21 +00:00
parent a5910d1b31
commit 8a00d8175b
1 changed files with 10 additions and 7 deletions
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17
llvm/lib/CodeGen/StrongPHIElimination.cpp
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@ -551,7 +551,8 @@ StrongPHIElimination::SplitInterferencesForBasicBlock(
// handle it here by tracking defining machine instructions rather than
// virtual registers. For now, we just handle the situation conservatively
// in a way that will possibly lead to false interferences.
unsigned NewParent = CurrentDominatingParent[DestColor];
unsigned &CurrentParent = CurrentDominatingParent[DestColor];
unsigned NewParent = CurrentParent;
if (NewParent == DestReg)
continue;
@ -570,12 +571,12 @@ StrongPHIElimination::SplitInterferencesForBasicBlock(
// could be improved by using a heuristic that decides which of the two
// registers to isolate.
isolateReg(DestReg);
CurrentDominatingParent[DestColor] = NewParent;
CurrentParent = NewParent;
} else {
// If there is no interference, update ImmediateDominatingParent and set
// the CurrentDominatingParent for this color to the current register.
ImmediateDominatingParent[DestReg] = NewParent;
CurrentDominatingParent[DestColor] = DestReg;
CurrentParent = DestReg;
}
}
}
@ -610,12 +611,13 @@ StrongPHIElimination::SplitInterferencesForBasicBlock(
// Pop registers from the stack represented by ImmediateDominatingParent
// until we find a parent that dominates the current instruction.
unsigned NewParent = CurrentDominatingParent[Color];
unsigned &CurrentParent = CurrentDominatingParent[Color];
unsigned NewParent = CurrentParent;
while (NewParent
&& (!DT->dominates(MRI->getVRegDef(NewParent)->getParent(), &MBB)
|| !getRegColor(NewParent)))
NewParent = ImmediateDominatingParent[NewParent];
CurrentDominatingParent[Color] = NewParent;
CurrentParent = NewParent;
// If there is an interference with a register, always isolate the
// register rather than the PHI. It is also possible to isolate the
@ -625,7 +627,8 @@ StrongPHIElimination::SplitInterferencesForBasicBlock(
&& NewParent != PredOperandReg)
isolateReg(NewParent);
std::pair<MachineInstr*, unsigned> CurrentPHI = CurrentPHIForColor[Color];
std::pair<MachineInstr*, unsigned>
&CurrentPHI = CurrentPHIForColor[Color];
// If two PHIs have the same operand from every shared predecessor, then
// they don't actually interfere. Otherwise, isolate the current PHI. This
@ -634,7 +637,7 @@ StrongPHIElimination::SplitInterferencesForBasicBlock(
if (CurrentPHI.first && CurrentPHI.second != PredOperandReg)
isolatePHI(PHI);
else
CurrentPHIForColor[Color] = std::make_pair(PHI, PredOperandReg);
CurrentPHI = std::make_pair(PHI, PredOperandReg);
}
}
}