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Revert "blockfreq: Approximate irreducible control flow"

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This reverts commit r207286.  It causes an ICE on the
cmake-llvm-x86_64-linux buildbot [1]:

    llvm/lib/Analysis/BlockFrequencyInfo.cpp: In lambda function:
    llvm/lib/Analysis/BlockFrequencyInfo.cpp:182:1: internal compiler error: in get_expr_operands, at tree-ssa-operands.c:1035

[1]: http://bb.pgr.jp/builders/cmake-llvm-x86_64-linux/builds/12093/steps/build_llvm/logs/stdio

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207287 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan P. N. Exon Smith
2014-04-25 23:16:58 +00:00
parent d905bba691
commit cee7abfb2c
3 changed files with 132 additions and 850 deletions
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230
lib/Analysis/BlockFrequencyInfoImpl.cpp
View File

@ -17,7 +17,6 @@
#include <deque>
using namespace llvm;
using namespace llvm::bfi_detail;
#define DEBUG_TYPE "block-freq"
@ -569,7 +568,7 @@ static void cleanup(BlockFrequencyInfoImplBase &BFI) {
BFI.Freqs = std::move(SavedFreqs);
}
bool BlockFrequencyInfoImplBase::addToDist(Distribution &Dist,
void BlockFrequencyInfoImplBase::addToDist(Distribution &Dist,
const LoopData *OuterLoop,
const BlockNode &Pred,
const BlockNode &Succ,
@ -599,48 +598,34 @@ bool BlockFrequencyInfoImplBase::addToDist(Distribution &Dist,
if (isLoopHeader(Resolved)) {
DEBUG(debugSuccessor("backedge"));
Dist.addBackedge(OuterLoop->getHeader(), Weight);
return true;
return;
}
if (Working[Resolved.Index].getContainingLoop() != OuterLoop) {
DEBUG(debugSuccessor(" exit "));
Dist.addExit(Resolved, Weight);
return true;
return;
}
if (Resolved < Pred) {
if (!isLoopHeader(Pred)) {
// If OuterLoop is an irreducible loop, we can't actually handle this.
assert((!OuterLoop || !OuterLoop->isIrreducible()) &&
"unhandled irreducible control flow");
// Irreducible backedge. Abort.
DEBUG(debugSuccessor("abort!!!"));
return false;
}
// If "Pred" is a loop header, then this isn't really a backedge; rather,
// OuterLoop must be irreducible. These false backedges can come only from
// secondary loop headers.
assert(OuterLoop && OuterLoop->isIrreducible() && !isLoopHeader(Resolved) &&
"unhandled irreducible control flow");
// Irreducible backedge. Skip.
DEBUG(debugSuccessor(" skip "));
return;
}
DEBUG(debugSuccessor(" local "));
Dist.addLocal(Resolved, Weight);
return true;
}
bool BlockFrequencyInfoImplBase::addLoopSuccessorsToDist(
void BlockFrequencyInfoImplBase::addLoopSuccessorsToDist(
const LoopData *OuterLoop, LoopData &Loop, Distribution &Dist) {
// Copy the exit map into Dist.
for (const auto &I : Loop.Exits)
if (!addToDist(Dist, OuterLoop, Loop.getHeader(), I.first,
I.second.getMass()))
// Irreducible backedge.
return false;
addToDist(Dist, OuterLoop, Loop.getHeader(), I.first, I.second.getMass());
return true;
// We don't need this map any more. Clear it to prevent quadratic memory
// usage in deeply nested loops with irreducible control flow.
Loop.Exits.clear();
}
/// \brief Get the maximum allowed loop scale.
@ -652,7 +637,8 @@ static Float getMaxLoopScale() { return Float(1, 12); }
/// \brief Compute the loop scale for a loop.
void BlockFrequencyInfoImplBase::computeLoopScale(LoopData &Loop) {
// Compute loop scale.
DEBUG(dbgs() << "compute-loop-scale: " << getLoopName(Loop) << "\n");
DEBUG(dbgs() << "compute-loop-scale: " << getBlockName(Loop.getHeader())
<< "\n");
// LoopScale == 1 / ExitMass
// ExitMass == HeadMass - BackedgeMass
@ -673,15 +659,12 @@ void BlockFrequencyInfoImplBase::computeLoopScale(LoopData &Loop) {
/// \brief Package up a loop.
void BlockFrequencyInfoImplBase::packageLoop(LoopData &Loop) {
DEBUG(dbgs() << "packaging-loop: " << getLoopName(Loop) << "\n");
// Clear the subloop exits to prevent quadratic memory usage.
for (const BlockNode &M : Loop.Nodes) {
if (auto *Loop = Working[M.Index].getPackagedLoop())
Loop->Exits.clear();
DEBUG(dbgs() << " - node: " << getBlockName(M.Index) << "\n");
}
DEBUG(dbgs() << "packaging-loop: " << getBlockName(Loop.getHeader()) << "\n");
Loop.IsPackaged = true;
DEBUG(for (const BlockNode &M
: Loop.members()) {
dbgs() << " - node: " << getBlockName(M.Index) << "\n";
});
}
void BlockFrequencyInfoImplBase::distributeMass(const BlockNode &Source,
@ -762,7 +745,7 @@ static void convertFloatingToInteger(BlockFrequencyInfoImplBase &BFI,
/// Visits all the members of a loop, adjusting their BlockData according to
/// the loop's pseudo-node.
static void unwrapLoop(BlockFrequencyInfoImplBase &BFI, LoopData &Loop) {
DEBUG(dbgs() << "unwrap-loop-package: " << BFI.getLoopName(Loop)
DEBUG(dbgs() << "unwrap-loop-package: " << BFI.getBlockName(Loop.getHeader())
<< ": mass = " << Loop.Mass << ", scale = " << Loop.Scale
<< "\n");
Loop.Scale *= Loop.Mass.toFloat();
@ -774,7 +757,7 @@ static void unwrapLoop(BlockFrequencyInfoImplBase &BFI, LoopData &Loop) {
// final head scale will be used for updated the rest of the members.
for (const BlockNode &N : Loop.Nodes) {
const auto &Working = BFI.Working[N.Index];
Float &F = Working.isAPackage() ? Working.getPackagedLoop()->Scale
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
@ -830,10 +813,6 @@ std::string
BlockFrequencyInfoImplBase::getBlockName(const BlockNode &Node) const {
return std::string();
}
std::string
BlockFrequencyInfoImplBase::getLoopName(const LoopData &Loop) const {
return getBlockName(Loop.getHeader()) + (Loop.isIrreducible() ? "**" : "*");
}
raw_ostream &
BlockFrequencyInfoImplBase::printBlockFreq(raw_ostream &OS,
@ -849,172 +828,3 @@ BlockFrequencyInfoImplBase::printBlockFreq(raw_ostream &OS,
return OS << Block / Entry;
}
void IrreducibleGraph::addNodesInLoop(const BFIBase::LoopData &OuterLoop) {
Start = OuterLoop.getHeader();
Nodes.reserve(OuterLoop.Nodes.size());
for (auto N : OuterLoop.Nodes)
addNode(N);
indexNodes();
}
void IrreducibleGraph::addNodesInFunction() {
Start = 0;
for (uint32_t Index = 0; Index < BFI.Working.size(); ++Index)
if (!BFI.Working[Index].isPackaged())
addNode(Index);
indexNodes();
}
void IrreducibleGraph::indexNodes() {
for (auto &I : Nodes)
Lookup[I.Node.Index] = &I;
}
void IrreducibleGraph::addEdge(IrrNode &Irr, const BlockNode &Succ,
const BFIBase::LoopData *OuterLoop) {
if (OuterLoop && OuterLoop->isHeader(Succ))
return;
auto L = Lookup.find(Succ.Index);
if (L == Lookup.end())
return;
IrrNode &SuccIrr = *L->second;
Irr.Edges.push_back(&SuccIrr);
SuccIrr.Edges.push_front(&Irr);
++SuccIrr.NumIn;
}
namespace llvm {
template <> struct GraphTraits<IrreducibleGraph> {
typedef bfi_detail::IrreducibleGraph GraphT;
typedef const typename GraphT::IrrNode NodeType;
typedef typename GraphT::IrrNode::iterator ChildIteratorType;
static const NodeType *getEntryNode(const GraphT &G) {
return G.StartIrr;
}
static ChildIteratorType child_begin(NodeType *N) { return N->succ_begin(); }
static ChildIteratorType child_end(NodeType *N) { return N->succ_end(); }
};
}
/// \brief Find extra irreducible headers.
///
/// Find entry blocks and other blocks with backedges, which exist when \c G
/// contains irreducible sub-SCCs.
static void findIrreducibleHeaders(
const BlockFrequencyInfoImplBase &BFI,
const IrreducibleGraph &G,
const std::vector<const IrreducibleGraph::IrrNode *> &SCC,
LoopData::NodeList &Headers, LoopData::NodeList &Others) {
// Map from nodes in the SCC to whether it's an entry block.
SmallDenseMap<const IrreducibleGraph::IrrNode *, bool, 8> InSCC;
// InSCC also acts the set of nodes in the graph. Seed it.
for (const auto *I : SCC)
InSCC[I] = false;
for (auto I = InSCC.begin(), E = InSCC.end(); I != E; ++I) {
auto &Irr = *I->first;
for (const auto *P : make_range(Irr.pred_begin(), Irr.pred_end())) {
if (InSCC.count(P))
continue;
// This is an entry block.
I->second = true;
Headers.push_back(Irr.Node);
DEBUG(dbgs() << " => entry = " << BFI.getBlockName(Irr.Node) << "\n");
break;
}
}
assert(Headers.size() >= 2 && "Should be irreducible");
if (Headers.size() == InSCC.size()) {
// Every block is a header.
std::sort(Headers.begin(), Headers.end());
return;
}
// Look for extra headers from irreducible sub-SCCs.
for (const auto &I : InSCC) {
// Entry blocks are already headers.
if (I.second)
continue;
auto &Irr = *I.first;
for (const auto *P : make_range(Irr.pred_begin(), Irr.pred_end())) {
// Skip forward edges.
if (P->Node < Irr.Node)
continue;
// Skip predecessors from entry blocks. These can have inverted
// ordering.
if (InSCC.lookup(P))
continue;
// Store the extra header.
Headers.push_back(Irr.Node);
DEBUG(dbgs() << " => extra = " << BFI.getBlockName(Irr.Node) << "\n");
break;
}
if (Headers.back() == Irr.Node)
// Added this as a header.
continue;
// This is not a header.
Others.push_back(Irr.Node);
DEBUG(dbgs() << " => other = " << BFI.getBlockName(Irr.Node) << "\n");
}
std::sort(Headers.begin(), Headers.end());
std::sort(Others.begin(), Others.end());
}
static void createIrreducibleLoop(
BlockFrequencyInfoImplBase &BFI, const IrreducibleGraph &G,
LoopData *OuterLoop, std::list<LoopData>::iterator Insert,
const std::vector<const IrreducibleGraph::IrrNode *> &SCC) {
// Translate the SCC into RPO.
DEBUG(dbgs() << " - found-scc\n");
LoopData::NodeList Headers;
LoopData::NodeList Others;
findIrreducibleHeaders(BFI, G, SCC, Headers, Others);
auto Loop = BFI.Loops.emplace(Insert, OuterLoop, Headers.begin(),
Headers.end(), Others.begin(), Others.end());
// Update loop hierarchy.
for (const auto &N : Loop->Nodes)
if (BFI.Working[N.Index].isLoopHeader())
BFI.Working[N.Index].Loop->Parent = &*Loop;
else
BFI.Working[N.Index].Loop = &*Loop;
}
iterator_range<std::list<LoopData>::iterator>
BlockFrequencyInfoImplBase::analyzeIrreducible(
const IrreducibleGraph &G, LoopData *OuterLoop,
std::list<LoopData>::iterator Insert) {
assert((OuterLoop == nullptr) == (Insert == Loops.begin()));
auto Prev = OuterLoop ? std::prev(Insert) : Loops.end();
for (auto I = scc_begin(G); !I.isAtEnd(); ++I) {
if (I->size() < 2)
continue;
// Translate the SCC into RPO.
createIrreducibleLoop(*this, G, OuterLoop, Insert, *I);
}
if (OuterLoop)
return make_range(std::next(Prev), Insert);
return make_range(Loops.begin(), Insert);
}
void
BlockFrequencyInfoImplBase::updateLoopWithIrreducible(LoopData &OuterLoop) {
OuterLoop.Exits.clear();
OuterLoop.BackedgeMass = BlockMass::getEmpty();
auto O = OuterLoop.Nodes.begin() + 1;
for (auto I = O, E = OuterLoop.Nodes.end(); I != E; ++I)
if (!Working[I->Index].isPackaged())
*O++ = *I;
OuterLoop.Nodes.erase(O, OuterLoop.Nodes.end());
}