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blockfreq: Scale LoopData::Scale on the way down 

Rather than scaling loop headers and then scaling all the loop members
by the header frequency, scale `LoopData::Scale` itself, and scale the
loop members by it.  It's much more obvious what's going on this way,
and doesn't cost any extra multiplies.

<rdar://problem/14292693>

llvm-svn: 207189
This commit is contained in:
Duncan P. N. Exon Smith 2014-04-25 04:38:27 +00:00
parent 0633f0ec29
commit 5291d2a561
1 changed files with 12 additions and 23 deletions
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35
llvm/lib/Analysis/BlockFrequencyInfoImpl.cpp
View File

@ -805,40 +805,29 @@ static void convertFloatingToInteger(BlockFrequencyInfoImplBase &BFI,
}
}
static void scaleBlockData(BlockFrequencyInfoImplBase &BFI,
const BlockNode &Node, const LoopData &Loop) {
Float F = Loop.Mass.toFloat() * Loop.Scale;
Float &Current = BFI.Freqs[Node.Index].Floating;
Float Updated = Current * F;
DEBUG(dbgs() << " - " << BFI.getBlockName(Node) << ": " << Current << " => "
<< Updated << "\n");
Current = Updated;
}
/// \brief Unwrap a loop package.
///
/// Visits all the members of a loop, adjusting their BlockData according to
/// the loop's pseudo-node.
static void unwrapLoop(BlockFrequencyInfoImplBase &BFI, LoopData &Loop) {
BlockNode Head = Loop.getHeader();
DEBUG(dbgs() << "unwrap-loop-package: " << BFI.getBlockName(Head)
DEBUG(dbgs() << "unwrap-loop-package: " << BFI.getBlockName(Loop.getHeader())
<< ": mass = " << Loop.Mass << ", scale = " << Loop.Scale
<< "\n");
scaleBlockData(BFI, Head, Loop);
Loop.Scale *= Loop.Mass.toFloat();
Loop.IsPackaged = false;
DEBUG(dbgs() << " => combined-scale = " << Loop.Scale << "\n");
// Propagate the head scale through the loop. Since members are visited in
// RPO, the head scale will be updated by the loop scale first, and then the
// final head scale will be used for updated the rest of the members.
for (const BlockNode &M : Loop.members()) {
const FrequencyData &HeadData = BFI.Freqs[Head.Index];
FrequencyData &Freqs = BFI.Freqs[M.Index];
Float NewFreq = Freqs.Floating * HeadData.Floating;
DEBUG(dbgs() << " - " << BFI.getBlockName(M) << ": " << Freqs.Floating
<< " => " << NewFreq << "\n");
Freqs.Floating = NewFreq;
for (const BlockNode &N : Loop.Nodes) {
const auto &Working = BFI.Working[N.Index];
Float &F = Working.isAPackage() ? BFI.getLoopPackage(N).Scale
: BFI.Freqs[N.Index].Floating;
Float New = Loop.Scale * F;
DEBUG(dbgs() << " - " << BFI.getBlockName(N) << ": " << F << " => " << New
<< "\n");
F = New;
}
}