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Part one of switching to using a more sane heuristic for determining if-conversion profitability.

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Rather than having arbitrary cutoffs, actually try to cost model the conversion.

For now, the constants are tuned to more or less match our existing behavior, but these will be
changed to reflect realistic values as this work proceeds.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114973 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson
2010-09-28 18:32:13 +00:00
parent f2d7b7c879
commit b20b85168c
7 changed files with 46 additions and 55 deletions
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8
lib/CodeGen/IfConversion.cpp
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@ -191,13 +191,13 @@ namespace {
void MergeBlocks(BBInfo &ToBBI, BBInfo &FromBBI, bool AddEdges = true);
bool MeetIfcvtSizeLimit(MachineBasicBlock &BB, unsigned Size) const {
return Size > 0 && TII->isProfitableToIfCvt(BB, Size);
return Size > 0 && TII->isProfitableToIfCvt(BB, Size, 0.5);
}
bool MeetIfcvtSizeLimit(MachineBasicBlock &TBB, unsigned TSize,
MachineBasicBlock &FBB, unsigned FSize) const {
return TSize > 0 && FSize > 0 &&
TII->isProfitableToIfCvt(TBB, TSize, FBB, FSize);
TII->isProfitableToIfCvt(TBB, TSize, FBB, FSize, 0.5);
}
// blockAlwaysFallThrough - Block ends without a terminator.
@ -444,7 +444,7 @@ bool IfConverter::ValidSimple(BBInfo &TrueBBI, unsigned &Dups) const {
if (TrueBBI.BB->pred_size() > 1) {
if (TrueBBI.CannotBeCopied ||
!TII->isProfitableToDupForIfCvt(*TrueBBI.BB, TrueBBI.NonPredSize))
!TII->isProfitableToDupForIfCvt(*TrueBBI.BB, TrueBBI.NonPredSize, 0.5))
return false;
Dups = TrueBBI.NonPredSize;
}
@ -481,7 +481,7 @@ bool IfConverter::ValidTriangle(BBInfo &TrueBBI, BBInfo &FalseBBI,
++Size;
}
}
if (!TII->isProfitableToDupForIfCvt(*TrueBBI.BB, Size))
if (!TII->isProfitableToDupForIfCvt(*TrueBBI.BB, Size, 0.5))
return false;
Dups = Size;
}