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llvm-project/llvm/lib/CodeGen/MachineTraceMetrics.cpp

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//===- lib/CodeGen/MachineTraceMetrics.cpp --------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/MachineTraceMetrics.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/SparseSet.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/CodeGen/TargetSchedule.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cassert>
#include <iterator>
#include <tuple>
#include <utility>
using namespace llvm;
#define DEBUG_TYPE "machine-trace-metrics"
char MachineTraceMetrics::ID = 0;
char &llvm::MachineTraceMetricsID = MachineTraceMetrics::ID;
INITIALIZE_PASS_BEGIN(MachineTraceMetrics, DEBUG_TYPE,
"Machine Trace Metrics", false, true)
INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfo)
INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
INITIALIZE_PASS_END(MachineTraceMetrics, DEBUG_TYPE,
"Machine Trace Metrics", false, true)
MachineTraceMetrics::MachineTraceMetrics() : MachineFunctionPass(ID) {
std::fill(std::begin(Ensembles), std::end(Ensembles), nullptr);
}
void MachineTraceMetrics::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequired<MachineBranchProbabilityInfo>();
AU.addRequired<MachineLoopInfo>();
MachineFunctionPass::getAnalysisUsage(AU);
}
bool MachineTraceMetrics::runOnMachineFunction(MachineFunction &Func) {
MF = &Func;
const TargetSubtargetInfo &ST = MF->getSubtarget();
TII = ST.getInstrInfo();
TRI = ST.getRegisterInfo();
MRI = &MF->getRegInfo();
Loops = &getAnalysis<MachineLoopInfo>();
SchedModel.init(ST.getSchedModel(), &ST, TII);
BlockInfo.resize(MF->getNumBlockIDs());
ProcResourceCycles.resize(MF->getNumBlockIDs() *
SchedModel.getNumProcResourceKinds());
return false;
}
void MachineTraceMetrics::releaseMemory() {
MF = nullptr;
BlockInfo.clear();
for (unsigned i = 0; i != TS_NumStrategies; ++i) {
delete Ensembles[i];
Ensembles[i] = nullptr;
}
}
//===----------------------------------------------------------------------===//
// Fixed block information
//===----------------------------------------------------------------------===//
//
// The number of instructions in a basic block and the CPU resources used by
// those instructions don't depend on any given trace strategy.
/// Compute the resource usage in basic block MBB.
const MachineTraceMetrics::FixedBlockInfo*
MachineTraceMetrics::getResources(const MachineBasicBlock *MBB) {
assert(MBB && "No basic block");
FixedBlockInfo *FBI = &BlockInfo[MBB->getNumber()];
if (FBI->hasResources())
return FBI;
// Compute resource usage in the block.
FBI->HasCalls = false;
unsigned InstrCount = 0;
// Add up per-processor resource cycles as well.
unsigned PRKinds = SchedModel.getNumProcResourceKinds();
SmallVector<unsigned, 32> PRCycles(PRKinds);
for (const auto &MI : *MBB) {
if (MI.isTransient())
continue;
++InstrCount;
if (MI.isCall())
FBI->HasCalls = true;
// Count processor resources used.
if (!SchedModel.hasInstrSchedModel())
continue;
const MCSchedClassDesc *SC = SchedModel.resolveSchedClass(&MI);
if (!SC->isValid())
continue;
for (TargetSchedModel::ProcResIter
PI = SchedModel.getWriteProcResBegin(SC),
PE = SchedModel.getWriteProcResEnd(SC); PI != PE; ++PI) {
assert(PI->ProcResourceIdx < PRKinds && "Bad processor resource kind");
PRCycles[PI->ProcResourceIdx] += PI->Cycles;
}
}
FBI->InstrCount = InstrCount;
// Scale the resource cycles so they are comparable.
unsigned PROffset = MBB->getNumber() * PRKinds;
for (unsigned K = 0; K != PRKinds; ++K)
ProcResourceCycles[PROffset + K] =
PRCycles[K] * SchedModel.getResourceFactor(K);
return FBI;
}
ArrayRef<unsigned>
MachineTraceMetrics::getProcResourceCycles(unsigned MBBNum) const {
assert(BlockInfo[MBBNum].hasResources() &&
"getResources() must be called before getProcResourceCycles()");
unsigned PRKinds = SchedModel.getNumProcResourceKinds();
assert((MBBNum+1) * PRKinds <= ProcResourceCycles.size());
return makeArrayRef(ProcResourceCycles.data() + MBBNum * PRKinds, PRKinds);
}
//===----------------------------------------------------------------------===//
// Ensemble utility functions
//===----------------------------------------------------------------------===//
MachineTraceMetrics::Ensemble::Ensemble(MachineTraceMetrics *ct)
: MTM(*ct) {
BlockInfo.resize(MTM.BlockInfo.size());
unsigned PRKinds = MTM.SchedModel.getNumProcResourceKinds();
ProcResourceDepths.resize(MTM.BlockInfo.size() * PRKinds);
ProcResourceHeights.resize(MTM.BlockInfo.size() * PRKinds);
}
// Virtual destructor serves as an anchor.
MachineTraceMetrics::Ensemble::~Ensemble() = default;
const MachineLoop*
MachineTraceMetrics::Ensemble::getLoopFor(const MachineBasicBlock *MBB) const {
return MTM.Loops->getLoopFor(MBB);
}
// Update resource-related information in the TraceBlockInfo for MBB.
// Only update resources related to the trace above MBB.
void MachineTraceMetrics::Ensemble::
computeDepthResources(const MachineBasicBlock *MBB) {
TraceBlockInfo *TBI = &BlockInfo[MBB->getNumber()];
unsigned PRKinds = MTM.SchedModel.getNumProcResourceKinds();
unsigned PROffset = MBB->getNumber() * PRKinds;
// Compute resources from trace above. The top block is simple.
if (!TBI->Pred) {
TBI->InstrDepth = 0;
TBI->Head = MBB->getNumber();
std::fill(ProcResourceDepths.begin() + PROffset,
ProcResourceDepths.begin() + PROffset + PRKinds, 0);
return;
}
// Compute from the block above. A post-order traversal ensures the
// predecessor is always computed first.
unsigned PredNum = TBI->Pred->getNumber();
TraceBlockInfo *PredTBI = &BlockInfo[PredNum];
assert(PredTBI->hasValidDepth() && "Trace above has not been computed yet");
const FixedBlockInfo *PredFBI = MTM.getResources(TBI->Pred);
TBI->InstrDepth = PredTBI->InstrDepth + PredFBI->InstrCount;
TBI->Head = PredTBI->Head;
// Compute per-resource depths.
ArrayRef<unsigned> PredPRDepths = getProcResourceDepths(PredNum);
ArrayRef<unsigned> PredPRCycles = MTM.getProcResourceCycles(PredNum);
for (unsigned K = 0; K != PRKinds; ++K)
ProcResourceDepths[PROffset + K] = PredPRDepths[K] + PredPRCycles[K];
}
// Update resource-related information in the TraceBlockInfo for MBB.
// Only update resources related to the trace below MBB.
void MachineTraceMetrics::Ensemble::
computeHeightResources(const MachineBasicBlock *MBB) {
TraceBlockInfo *TBI = &BlockInfo[MBB->getNumber()];
unsigned PRKinds = MTM.SchedModel.getNumProcResourceKinds();
unsigned PROffset = MBB->getNumber() * PRKinds;
// Compute resources for the current block.
TBI->InstrHeight = MTM.getResources(MBB)->InstrCount;
ArrayRef<unsigned> PRCycles = MTM.getProcResourceCycles(MBB->getNumber());
// The trace tail is done.
if (!TBI->Succ) {
TBI->Tail = MBB->getNumber();
std::copy(PRCycles.begin(), PRCycles.end(),
ProcResourceHeights.begin() + PROffset);
return;
}
// Compute from the block below. A post-order traversal ensures the
// predecessor is always computed first.
unsigned SuccNum = TBI->Succ->getNumber();
TraceBlockInfo *SuccTBI = &BlockInfo[SuccNum];
assert(SuccTBI->hasValidHeight() && "Trace below has not been computed yet");
TBI->InstrHeight += SuccTBI->InstrHeight;
TBI->Tail = SuccTBI->Tail;
// Compute per-resource heights.
ArrayRef<unsigned> SuccPRHeights = getProcResourceHeights(SuccNum);
for (unsigned K = 0; K != PRKinds; ++K)
ProcResourceHeights[PROffset + K] = SuccPRHeights[K] + PRCycles[K];
}
// Check if depth resources for MBB are valid and return the TBI.
// Return NULL if the resources have been invalidated.
const MachineTraceMetrics::TraceBlockInfo*
MachineTraceMetrics::Ensemble::
getDepthResources(const MachineBasicBlock *MBB) const {
const TraceBlockInfo *TBI = &BlockInfo[MBB->getNumber()];
return TBI->hasValidDepth() ? TBI : nullptr;
}
// Check if height resources for MBB are valid and return the TBI.
// Return NULL if the resources have been invalidated.
const MachineTraceMetrics::TraceBlockInfo*
MachineTraceMetrics::Ensemble::
getHeightResources(const MachineBasicBlock *MBB) const {
const TraceBlockInfo *TBI = &BlockInfo[MBB->getNumber()];
return TBI->hasValidHeight() ? TBI : nullptr;
}
/// Get an array of processor resource depths for MBB. Indexed by processor
/// resource kind, this array contains the scaled processor resources consumed
/// by all blocks preceding MBB in its trace. It does not include instructions
/// in MBB.
///
/// Compare TraceBlockInfo::InstrDepth.
ArrayRef<unsigned>
MachineTraceMetrics::Ensemble::
getProcResourceDepths(unsigned MBBNum) const {
unsigned PRKinds = MTM.SchedModel.getNumProcResourceKinds();
assert((MBBNum+1) * PRKinds <= ProcResourceDepths.size());
return makeArrayRef(ProcResourceDepths.data() + MBBNum * PRKinds, PRKinds);
}
/// Get an array of processor resource heights for MBB. Indexed by processor
/// resource kind, this array contains the scaled processor resources consumed
/// by this block and all blocks following it in its trace.
///
/// Compare TraceBlockInfo::InstrHeight.
ArrayRef<unsigned>
MachineTraceMetrics::Ensemble::
getProcResourceHeights(unsigned MBBNum) const {
unsigned PRKinds = MTM.SchedModel.getNumProcResourceKinds();
assert((MBBNum+1) * PRKinds <= ProcResourceHeights.size());
return makeArrayRef(ProcResourceHeights.data() + MBBNum * PRKinds, PRKinds);
}
//===----------------------------------------------------------------------===//
// Trace Selection Strategies
//===----------------------------------------------------------------------===//
//
// A trace selection strategy is implemented as a sub-class of Ensemble. The
// trace through a block B is computed by two DFS traversals of the CFG
// starting from B. One upwards, and one downwards. During the upwards DFS,
// pickTracePred() is called on the post-ordered blocks. During the downwards
// DFS, pickTraceSucc() is called in a post-order.
//
// We never allow traces that leave loops, but we do allow traces to enter
// nested loops. We also never allow traces to contain back-edges.
//
// This means that a loop header can never appear above the center block of a
// trace, except as the trace head. Below the center block, loop exiting edges
// are banned.
//
// Return true if an edge from the From loop to the To loop is leaving a loop.
// Either of To and From can be null.
static bool isExitingLoop(const MachineLoop *From, const MachineLoop *To) {
return From && !From->contains(To);
}
// MinInstrCountEnsemble - Pick the trace that executes the least number of
// instructions.
namespace {
class MinInstrCountEnsemble : public MachineTraceMetrics::Ensemble {
const char *getName() const override { return "MinInstr"; }
const MachineBasicBlock *pickTracePred(const MachineBasicBlock*) override;
const MachineBasicBlock *pickTraceSucc(const MachineBasicBlock*) override;
public:
MinInstrCountEnsemble(MachineTraceMetrics *mtm)
: MachineTraceMetrics::Ensemble(mtm) {}
};
} // end anonymous namespace
// Select the preferred predecessor for MBB.
const MachineBasicBlock*
MinInstrCountEnsemble::pickTracePred(const MachineBasicBlock *MBB) {
if (MBB->pred_empty())
return nullptr;
const MachineLoop *CurLoop = getLoopFor(MBB);
// Don't leave loops, and never follow back-edges.
if (CurLoop && MBB == CurLoop->getHeader())
return nullptr;
unsigned CurCount = MTM.getResources(MBB)->InstrCount;
const MachineBasicBlock *Best = nullptr;
unsigned BestDepth = 0;
for (const MachineBasicBlock *Pred : MBB->predecessors()) {
const MachineTraceMetrics::TraceBlockInfo *PredTBI =
getDepthResources(Pred);
// Ignore cycles that aren't natural loops.
if (!PredTBI)
continue;
// Pick the predecessor that would give this block the smallest InstrDepth.
unsigned Depth = PredTBI->InstrDepth + CurCount;
if (!Best || Depth < BestDepth) {
Best = Pred;
BestDepth = Depth;
}
}
return Best;
}
// Select the preferred successor for MBB.
const MachineBasicBlock*
MinInstrCountEnsemble::pickTraceSucc(const MachineBasicBlock *MBB) {
if (MBB->pred_empty())
return nullptr;
const MachineLoop *CurLoop = getLoopFor(MBB);
const MachineBasicBlock *Best = nullptr;
unsigned BestHeight = 0;
for (const MachineBasicBlock *Succ : MBB->successors()) {
// Don't consider back-edges.
if (CurLoop && Succ == CurLoop->getHeader())
continue;
// Don't consider successors exiting CurLoop.
if (isExitingLoop(CurLoop, getLoopFor(Succ)))
continue;
const MachineTraceMetrics::TraceBlockInfo *SuccTBI =
getHeightResources(Succ);
// Ignore cycles that aren't natural loops.
if (!SuccTBI)
continue;
// Pick the successor that would give this block the smallest InstrHeight.
unsigned Height = SuccTBI->InstrHeight;
if (!Best || Height < BestHeight) {
Best = Succ;
BestHeight = Height;
}
}
return Best;
}
// Get an Ensemble sub-class for the requested trace strategy.
MachineTraceMetrics::Ensemble *
MachineTraceMetrics::getEnsemble(MachineTraceMetrics::Strategy strategy) {
assert(strategy < TS_NumStrategies && "Invalid trace strategy enum");
Ensemble *&E = Ensembles[strategy];
if (E)
return E;
// Allocate new Ensemble on demand.
switch (strategy) {
case TS_MinInstrCount: return (E = new MinInstrCountEnsemble(this));
default: llvm_unreachable("Invalid trace strategy enum");
}
}
void MachineTraceMetrics::invalidate(const MachineBasicBlock *MBB) {
DEBUG(dbgs() << "Invalidate traces through BB#" << MBB->getNumber() << '\n');
BlockInfo[MBB->getNumber()].invalidate();
for (unsigned i = 0; i != TS_NumStrategies; ++i)
if (Ensembles[i])
Ensembles[i]->invalidate(MBB);
}
void MachineTraceMetrics::verifyAnalysis() const {
if (!MF)
return;
#ifndef NDEBUG
assert(BlockInfo.size() == MF->getNumBlockIDs() && "Outdated BlockInfo size");
for (unsigned i = 0; i != TS_NumStrategies; ++i)
if (Ensembles[i])
Ensembles[i]->verify();
#endif
}
//===----------------------------------------------------------------------===//
// Trace building
//===----------------------------------------------------------------------===//
//
// Traces are built by two CFG traversals. To avoid recomputing too much, use a
// set abstraction that confines the search to the current loop, and doesn't
// revisit blocks.
namespace {
struct LoopBounds {
MutableArrayRef<MachineTraceMetrics::TraceBlockInfo> Blocks;
SmallPtrSet<const MachineBasicBlock*, 8> Visited;
const MachineLoopInfo *Loops;
bool Downward = false;
LoopBounds(MutableArrayRef<MachineTraceMetrics::TraceBlockInfo> blocks,
const MachineLoopInfo *loops) : Blocks(blocks), Loops(loops) {}
};
} // end anonymous namespace
// Specialize po_iterator_storage in order to prune the post-order traversal so
// it is limited to the current loop and doesn't traverse the loop back edges.
namespace llvm {
template<>
class po_iterator_storage<LoopBounds, true> {
LoopBounds &LB;
public:
po_iterator_storage(LoopBounds &lb) : LB(lb) {}
void finishPostorder(const MachineBasicBlock*) {}
bool insertEdge(Optional<const MachineBasicBlock *> From,
const MachineBasicBlock *To) {
// Skip already visited To blocks.
MachineTraceMetrics::TraceBlockInfo &TBI = LB.Blocks[To->getNumber()];
if (LB.Downward ? TBI.hasValidHeight() : TBI.hasValidDepth())
return false;
// From is null once when To is the trace center block.
if (From) {
if (const MachineLoop *FromLoop = LB.Loops->getLoopFor(*From)) {
// Don't follow backedges, don't leave FromLoop when going upwards.
if ((LB.Downward ? To : *From) == FromLoop->getHeader())
return false;
// Don't leave FromLoop.
if (isExitingLoop(FromLoop, LB.Loops->getLoopFor(To)))
return false;
}
}
// To is a new block. Mark the block as visited in case the CFG has cycles
// that MachineLoopInfo didn't recognize as a natural loop.
return LB.Visited.insert(To).second;
}
};
} // end namespace llvm
/// Compute the trace through MBB.
void MachineTraceMetrics::Ensemble::computeTrace(const MachineBasicBlock *MBB) {
DEBUG(dbgs() << "Computing " << getName() << " trace through BB#"
<< MBB->getNumber() << '\n');
// Set up loop bounds for the backwards post-order traversal.
LoopBounds Bounds(BlockInfo, MTM.Loops);
// Run an upwards post-order search for the trace start.
Bounds.Downward = false;
Bounds.Visited.clear();
for (auto I : inverse_post_order_ext(MBB, Bounds)) {
DEBUG(dbgs() << " pred for BB#" << I->getNumber() << ": ");
TraceBlockInfo &TBI = BlockInfo[I->getNumber()];
// All the predecessors have been visited, pick the preferred one.
TBI.Pred = pickTracePred(I);
DEBUG({
if (TBI.Pred)
dbgs() << "BB#" << TBI.Pred->getNumber() << '\n';
else
dbgs() << "null\n";
});
// The trace leading to I is now known, compute the depth resources.
computeDepthResources(I);
}
// Run a downwards post-order search for the trace end.
Bounds.Downward = true;
Bounds.Visited.clear();
for (auto I : post_order_ext(MBB, Bounds)) {
DEBUG(dbgs() << " succ for BB#" << I->getNumber() << ": ");
TraceBlockInfo &TBI = BlockInfo[I->getNumber()];
// All the successors have been visited, pick the preferred one.
TBI.Succ = pickTraceSucc(I);
DEBUG({
if (TBI.Succ)
dbgs() << "BB#" << TBI.Succ->getNumber() << '\n';
else
dbgs() << "null\n";
});
// The trace leaving I is now known, compute the height resources.
computeHeightResources(I);
}
}
/// Invalidate traces through BadMBB.
void
MachineTraceMetrics::Ensemble::invalidate(const MachineBasicBlock *BadMBB) {
SmallVector<const MachineBasicBlock*, 16> WorkList;
TraceBlockInfo &BadTBI = BlockInfo[BadMBB->getNumber()];
// Invalidate height resources of blocks above MBB.
if (BadTBI.hasValidHeight()) {
BadTBI.invalidateHeight();
WorkList.push_back(BadMBB);
do {
const MachineBasicBlock *MBB = WorkList.pop_back_val();
DEBUG(dbgs() << "Invalidate BB#" << MBB->getNumber() << ' ' << getName()
<< " height.\n");
// Find any MBB predecessors that have MBB as their preferred successor.
// They are the only ones that need to be invalidated.
for (const MachineBasicBlock *Pred : MBB->predecessors()) {
TraceBlockInfo &TBI = BlockInfo[Pred->getNumber()];
if (!TBI.hasValidHeight())
continue;
if (TBI.Succ == MBB) {
TBI.invalidateHeight();
WorkList.push_back(Pred);
continue;
}
// Verify that TBI.Succ is actually a *I successor.
assert((!TBI.Succ || Pred->isSuccessor(TBI.Succ)) && "CFG changed");
}
} while (!WorkList.empty());
}
// Invalidate depth resources of blocks below MBB.
if (BadTBI.hasValidDepth()) {
BadTBI.invalidateDepth();
WorkList.push_back(BadMBB);
do {
const MachineBasicBlock *MBB = WorkList.pop_back_val();
DEBUG(dbgs() << "Invalidate BB#" << MBB->getNumber() << ' ' << getName()
<< " depth.\n");
// Find any MBB successors that have MBB as their preferred predecessor.
// They are the only ones that need to be invalidated.
for (const MachineBasicBlock *Succ : MBB->successors()) {
TraceBlockInfo &TBI = BlockInfo[Succ->getNumber()];
if (!TBI.hasValidDepth())
continue;
if (TBI.Pred == MBB) {
TBI.invalidateDepth();
WorkList.push_back(Succ);
continue;
}
// Verify that TBI.Pred is actually a *I predecessor.
assert((!TBI.Pred || Succ->isPredecessor(TBI.Pred)) && "CFG changed");
}
} while (!WorkList.empty());
}
// Clear any per-instruction data. We only have to do this for BadMBB itself
// because the instructions in that block may change. Other blocks may be
// invalidated, but their instructions will stay the same, so there is no
// need to erase the Cycle entries. They will be overwritten when we
// recompute.
for (const auto &I : *BadMBB)
Cycles.erase(&I);
}
void MachineTraceMetrics::Ensemble::verify() const {
#ifndef NDEBUG
assert(BlockInfo.size() == MTM.MF->getNumBlockIDs() &&
"Outdated BlockInfo size");
for (unsigned Num = 0, e = BlockInfo.size(); Num != e; ++Num) {
const TraceBlockInfo &TBI = BlockInfo[Num];
if (TBI.hasValidDepth() && TBI.Pred) {
const MachineBasicBlock *MBB = MTM.MF->getBlockNumbered(Num);
assert(MBB->isPredecessor(TBI.Pred) && "CFG doesn't match trace");
assert(BlockInfo[TBI.Pred->getNumber()].hasValidDepth() &&
"Trace is broken, depth should have been invalidated.");
const MachineLoop *Loop = getLoopFor(MBB);
assert(!(Loop && MBB == Loop->getHeader()) && "Trace contains backedge");
}
if (TBI.hasValidHeight() && TBI.Succ) {
const MachineBasicBlock *MBB = MTM.MF->getBlockNumbered(Num);
assert(MBB->isSuccessor(TBI.Succ) && "CFG doesn't match trace");
assert(BlockInfo[TBI.Succ->getNumber()].hasValidHeight() &&
"Trace is broken, height should have been invalidated.");
const MachineLoop *Loop = getLoopFor(MBB);
const MachineLoop *SuccLoop = getLoopFor(TBI.Succ);
assert(!(Loop && Loop == SuccLoop && TBI.Succ == Loop->getHeader()) &&
"Trace contains backedge");
}
}
#endif
}
//===----------------------------------------------------------------------===//
// Data Dependencies
//===----------------------------------------------------------------------===//
//
// Compute the depth and height of each instruction based on data dependencies
// and instruction latencies. These cycle numbers assume that the CPU can issue
// an infinite number of instructions per cycle as long as their dependencies
// are ready.
// A data dependency is represented as a defining MI and operand numbers on the
// defining and using MI.
namespace {
struct DataDep {
const MachineInstr *DefMI;
unsigned DefOp;
unsigned UseOp;
DataDep(const MachineInstr *DefMI, unsigned DefOp, unsigned UseOp)
: DefMI(DefMI), DefOp(DefOp), UseOp(UseOp) {}
/// Create a DataDep from an SSA form virtual register.
DataDep(const MachineRegisterInfo *MRI, unsigned VirtReg, unsigned UseOp)
: UseOp(UseOp) {
assert(TargetRegisterInfo::isVirtualRegister(VirtReg));
MachineRegisterInfo::def_iterator DefI = MRI->def_begin(VirtReg);
assert(!DefI.atEnd() && "Register has no defs");
DefMI = DefI->getParent();
DefOp = DefI.getOperandNo();
assert((++DefI).atEnd() && "Register has multiple defs");
}
};
} // end anonymous namespace
// Get the input data dependencies that must be ready before UseMI can issue.
// Return true if UseMI has any physreg operands.
static bool getDataDeps(const MachineInstr &UseMI,
SmallVectorImpl<DataDep> &Deps,
const MachineRegisterInfo *MRI) {
// Debug values should not be included in any calculations.
if (UseMI.isDebugValue())
return false;
bool HasPhysRegs = false;
for (MachineInstr::const_mop_iterator I = UseMI.operands_begin(),
E = UseMI.operands_end(); I != E; ++I) {
const MachineOperand &MO = *I;
if (!MO.isReg())
continue;
unsigned Reg = MO.getReg();
if (!Reg)
continue;
if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
HasPhysRegs = true;
continue;
}
// Collect virtual register reads.
if (MO.readsReg())
Deps.push_back(DataDep(MRI, Reg, UseMI.getOperandNo(I)));
}
return HasPhysRegs;
}
// Get the input data dependencies of a PHI instruction, using Pred as the
// preferred predecessor.
// This will add at most one dependency to Deps.
static void getPHIDeps(const MachineInstr &UseMI,
SmallVectorImpl<DataDep> &Deps,
const MachineBasicBlock *Pred,
const MachineRegisterInfo *MRI) {
// No predecessor at the beginning of a trace. Ignore dependencies.
if (!Pred)
return;
assert(UseMI.isPHI() && UseMI.getNumOperands() % 2 && "Bad PHI");
for (unsigned i = 1; i != UseMI.getNumOperands(); i += 2) {
if (UseMI.getOperand(i + 1).getMBB() == Pred) {
unsigned Reg = UseMI.getOperand(i).getReg();
Deps.push_back(DataDep(MRI, Reg, i));
return;
}
}
}
// Identify physreg dependencies for UseMI, and update the live regunit
// tracking set when scanning instructions downwards.
static void updatePhysDepsDownwards(const MachineInstr *UseMI,
SmallVectorImpl<DataDep> &Deps,
SparseSet<LiveRegUnit> &RegUnits,
const TargetRegisterInfo *TRI) {
SmallVector<unsigned, 8> Kills;
SmallVector<unsigned, 8> LiveDefOps;
for (MachineInstr::const_mop_iterator MI = UseMI->operands_begin(),
ME = UseMI->operands_end(); MI != ME; ++MI) {
const MachineOperand &MO = *MI;
if (!MO.isReg())
continue;
unsigned Reg = MO.getReg();
if (!TargetRegisterInfo::isPhysicalRegister(Reg))
continue;
// Track live defs and kills for updating RegUnits.
if (MO.isDef()) {
if (MO.isDead())
Kills.push_back(Reg);
else
LiveDefOps.push_back(UseMI->getOperandNo(MI));
} else if (MO.isKill())
Kills.push_back(Reg);
// Identify dependencies.
if (!MO.readsReg())
continue;
for (MCRegUnitIterator Units(Reg, TRI); Units.isValid(); ++Units) {
SparseSet<LiveRegUnit>::iterator I = RegUnits.find(*Units);
if (I == RegUnits.end())
continue;
Deps.push_back(DataDep(I->MI, I->Op, UseMI->getOperandNo(MI)));
break;
}
}
// Update RegUnits to reflect live registers after UseMI.
// First kills.
for (unsigned Kill : Kills)
for (MCRegUnitIterator Units(Kill, TRI); Units.isValid(); ++Units)
RegUnits.erase(*Units);
// Second, live defs.
for (unsigned DefOp : LiveDefOps) {
for (MCRegUnitIterator Units(UseMI->getOperand(DefOp).getReg(), TRI);
Units.isValid(); ++Units) {
LiveRegUnit &LRU = RegUnits[*Units];
LRU.MI = UseMI;
LRU.Op = DefOp;
}
}
}
/// The length of the critical path through a trace is the maximum of two path
/// lengths:
///
/// 1. The maximum height+depth over all instructions in the trace center block.
///
/// 2. The longest cross-block dependency chain. For small blocks, it is
/// possible that the critical path through the trace doesn't include any
/// instructions in the block.
///
/// This function computes the second number from the live-in list of the
/// center block.
unsigned MachineTraceMetrics::Ensemble::
computeCrossBlockCriticalPath(const TraceBlockInfo &TBI) {
assert(TBI.HasValidInstrDepths && "Missing depth info");
assert(TBI.HasValidInstrHeights && "Missing height info");
unsigned MaxLen = 0;
for (const LiveInReg &LIR : TBI.LiveIns) {
if (!TargetRegisterInfo::isVirtualRegister(LIR.Reg))
continue;
const MachineInstr *DefMI = MTM.MRI->getVRegDef(LIR.Reg);
// Ignore dependencies outside the current trace.
const TraceBlockInfo &DefTBI = BlockInfo[DefMI->getParent()->getNumber()];
if (!DefTBI.isUsefulDominator(TBI))
continue;
unsigned Len = LIR.Height + Cycles[DefMI].Depth;
MaxLen = std::max(MaxLen, Len);
}
return MaxLen;
}
void MachineTraceMetrics::Ensemble::
updateDepth(MachineTraceMetrics::TraceBlockInfo &TBI, const MachineInstr &UseMI,
SparseSet<LiveRegUnit> &RegUnits) {
SmallVector<DataDep, 8> Deps;
// Collect all data dependencies.
if (UseMI.isPHI())
getPHIDeps(UseMI, Deps, TBI.Pred, MTM.MRI);
else if (getDataDeps(UseMI, Deps, MTM.MRI))
updatePhysDepsDownwards(&UseMI, Deps, RegUnits, MTM.TRI);
// Filter and process dependencies, computing the earliest issue cycle.
unsigned Cycle = 0;
for (const DataDep &Dep : Deps) {
const TraceBlockInfo&DepTBI =
BlockInfo[Dep.DefMI->getParent()->getNumber()];
// Ignore dependencies from outside the current trace.
if (!DepTBI.isUsefulDominator(TBI))
continue;
assert(DepTBI.HasValidInstrDepths && "Inconsistent dependency");
unsigned DepCycle = Cycles.lookup(Dep.DefMI).Depth;
// Add latency if DefMI is a real instruction. Transients get latency 0.
if (!Dep.DefMI->isTransient())
DepCycle += MTM.SchedModel
.computeOperandLatency(Dep.DefMI, Dep.DefOp, &UseMI, Dep.UseOp);
Cycle = std::max(Cycle, DepCycle);
}
// Remember the instruction depth.
InstrCycles &MICycles = Cycles[&UseMI];
MICycles.Depth = Cycle;
if (TBI.HasValidInstrHeights) {
// Update critical path length.
TBI.CriticalPath = std::max(TBI.CriticalPath, Cycle + MICycles.Height);
DEBUG(dbgs() << TBI.CriticalPath << '\t' << Cycle << '\t' << UseMI);
} else {
DEBUG(dbgs() << Cycle << '\t' << UseMI);
}
}
void MachineTraceMetrics::Ensemble::
updateDepth(const MachineBasicBlock *MBB, const MachineInstr &UseMI,
SparseSet<LiveRegUnit> &RegUnits) {
updateDepth(BlockInfo[MBB->getNumber()], UseMI, RegUnits);
}
void MachineTraceMetrics::Ensemble::
updateDepths(MachineBasicBlock::iterator Start,
MachineBasicBlock::iterator End,
SparseSet<LiveRegUnit> &RegUnits) {
for (; Start != End; Start++)
updateDepth(Start->getParent(), *Start, RegUnits);
}
/// Compute instruction depths for all instructions above or in MBB in its
/// trace. This assumes that the trace through MBB has already been computed.
void MachineTraceMetrics::Ensemble::
computeInstrDepths(const MachineBasicBlock *MBB) {
// The top of the trace may already be computed, and HasValidInstrDepths
// implies Head->HasValidInstrDepths, so we only need to start from the first
// block in the trace that needs to be recomputed.
SmallVector<const MachineBasicBlock*, 8> Stack;
do {
TraceBlockInfo &TBI = BlockInfo[MBB->getNumber()];
assert(TBI.hasValidDepth() && "Incomplete trace");
if (TBI.HasValidInstrDepths)
break;
Stack.push_back(MBB);
MBB = TBI.Pred;
} while (MBB);
// FIXME: If MBB is non-null at this point, it is the last pre-computed block
// in the trace. We should track any live-out physregs that were defined in
// the trace. This is quite rare in SSA form, typically created by CSE
// hoisting a compare.
SparseSet<LiveRegUnit> RegUnits;
RegUnits.setUniverse(MTM.TRI->getNumRegUnits());
// Go through trace blocks in top-down order, stopping after the center block.
while (!Stack.empty()) {
MBB = Stack.pop_back_val();
DEBUG(dbgs() << "\nDepths for BB#" << MBB->getNumber() << ":\n");
TraceBlockInfo &TBI = BlockInfo[MBB->getNumber()];
TBI.HasValidInstrDepths = true;
TBI.CriticalPath = 0;
// Print out resource depths here as well.
DEBUG({
dbgs() << format("%7u Instructions\n", TBI.InstrDepth);
ArrayRef<unsigned> PRDepths = getProcResourceDepths(MBB->getNumber());
for (unsigned K = 0; K != PRDepths.size(); ++K)
if (PRDepths[K]) {
unsigned Factor = MTM.SchedModel.getResourceFactor(K);
dbgs() << format("%6uc @ ", MTM.getCycles(PRDepths[K]))
<< MTM.SchedModel.getProcResource(K)->Name << " ("
<< PRDepths[K]/Factor << " ops x" << Factor << ")\n";
}
});
// Also compute the critical path length through MBB when possible.
if (TBI.HasValidInstrHeights)
TBI.CriticalPath = computeCrossBlockCriticalPath(TBI);
for (const auto &UseMI : *MBB) {
updateDepth(TBI, UseMI, RegUnits);
}
}
}
// Identify physreg dependencies for MI when scanning instructions upwards.
// Return the issue height of MI after considering any live regunits.
// Height is the issue height computed from virtual register dependencies alone.
static unsigned updatePhysDepsUpwards(const MachineInstr &MI, unsigned Height,
SparseSet<LiveRegUnit> &RegUnits,
const TargetSchedModel &SchedModel,
const TargetInstrInfo *TII,
const TargetRegisterInfo *TRI) {
SmallVector<unsigned, 8> ReadOps;
for (MachineInstr::const_mop_iterator MOI = MI.operands_begin(),
MOE = MI.operands_end();
MOI != MOE; ++MOI) {
const MachineOperand &MO = *MOI;
if (!MO.isReg())
continue;
unsigned Reg = MO.getReg();
if (!TargetRegisterInfo::isPhysicalRegister(Reg))
continue;
if (MO.readsReg())
ReadOps.push_back(MI.getOperandNo(MOI));
if (!MO.isDef())
continue;
// This is a def of Reg. Remove corresponding entries from RegUnits, and
// update MI Height to consider the physreg dependencies.
for (MCRegUnitIterator Units(Reg, TRI); Units.isValid(); ++Units) {
SparseSet<LiveRegUnit>::iterator I = RegUnits.find(*Units);
if (I == RegUnits.end())
continue;
unsigned DepHeight = I->Cycle;
if (!MI.isTransient()) {
// We may not know the UseMI of this dependency, if it came from the
// live-in list. SchedModel can handle a NULL UseMI.
DepHeight += SchedModel.computeOperandLatency(&MI, MI.getOperandNo(MOI),
I->MI, I->Op);
}
Height = std::max(Height, DepHeight);
// This regunit is dead above MI.
RegUnits.erase(I);
}
}
// Now we know the height of MI. Update any regunits read.
for (unsigned i = 0, e = ReadOps.size(); i != e; ++i) {
unsigned Reg = MI.getOperand(ReadOps[i]).getReg();
for (MCRegUnitIterator Units(Reg, TRI); Units.isValid(); ++Units) {
LiveRegUnit &LRU = RegUnits[*Units];
// Set the height to the highest reader of the unit.
if (LRU.Cycle <= Height && LRU.MI != &MI) {
LRU.Cycle = Height;
LRU.MI = &MI;
LRU.Op = ReadOps[i];
}
}
}
return Height;
}
using MIHeightMap = DenseMap<const MachineInstr *, unsigned>;
// Push the height of DefMI upwards if required to match UseMI.
// Return true if this is the first time DefMI was seen.
static bool pushDepHeight(const DataDep &Dep, const MachineInstr &UseMI,
unsigned UseHeight, MIHeightMap &Heights,
const TargetSchedModel &SchedModel,
const TargetInstrInfo *TII) {
// Adjust height by Dep.DefMI latency.
if (!Dep.DefMI->isTransient())
UseHeight += SchedModel.computeOperandLatency(Dep.DefMI, Dep.DefOp, &UseMI,
Dep.UseOp);
// Update Heights[DefMI] to be the maximum height seen.
MIHeightMap::iterator I;
bool New;
std::tie(I, New) = Heights.insert(std::make_pair(Dep.DefMI, UseHeight));
if (New)
return true;
// DefMI has been pushed before. Give it the max height.
if (I->second < UseHeight)
I->second = UseHeight;
return false;
}
/// Assuming that the virtual register defined by DefMI:DefOp was used by
/// Trace.back(), add it to the live-in lists of all the blocks in Trace. Stop
/// when reaching the block that contains DefMI.
void MachineTraceMetrics::Ensemble::
addLiveIns(const MachineInstr *DefMI, unsigned DefOp,
ArrayRef<const MachineBasicBlock*> Trace) {
assert(!Trace.empty() && "Trace should contain at least one block");
unsigned Reg = DefMI->getOperand(DefOp).getReg();
assert(TargetRegisterInfo::isVirtualRegister(Reg));
const MachineBasicBlock *DefMBB = DefMI->getParent();
// Reg is live-in to all blocks in Trace that follow DefMBB.
for (unsigned i = Trace.size(); i; --i) {
const MachineBasicBlock *MBB = Trace[i-1];
if (MBB == DefMBB)
return;
TraceBlockInfo &TBI = BlockInfo[MBB->getNumber()];
// Just add the register. The height will be updated later.
TBI.LiveIns.push_back(Reg);
}
}
/// Compute instruction heights in the trace through MBB. This updates MBB and
/// the blocks below it in the trace. It is assumed that the trace has already
/// been computed.
void MachineTraceMetrics::Ensemble::
computeInstrHeights(const MachineBasicBlock *MBB) {
// The bottom of the trace may already be computed.
// Find the blocks that need updating.
SmallVector<const MachineBasicBlock*, 8> Stack;
do {
TraceBlockInfo &TBI = BlockInfo[MBB->getNumber()];
assert(TBI.hasValidHeight() && "Incomplete trace");
if (TBI.HasValidInstrHeights)
break;
Stack.push_back(MBB);
TBI.LiveIns.clear();
MBB = TBI.Succ;
} while (MBB);
// As we move upwards in the trace, keep track of instructions that are
// required by deeper trace instructions. Map MI -> height required so far.
MIHeightMap Heights;
// For physregs, the def isn't known when we see the use.
// Instead, keep track of the highest use of each regunit.
SparseSet<LiveRegUnit> RegUnits;
RegUnits.setUniverse(MTM.TRI->getNumRegUnits());
// If the bottom of the trace was already precomputed, initialize heights
// from its live-in list.
// MBB is the highest precomputed block in the trace.
if (MBB) {
TraceBlockInfo &TBI = BlockInfo[MBB->getNumber()];
for (LiveInReg &LI : TBI.LiveIns) {
if (TargetRegisterInfo::isVirtualRegister(LI.Reg)) {
// For virtual registers, the def latency is included.
unsigned &Height = Heights[MTM.MRI->getVRegDef(LI.Reg)];
if (Height < LI.Height)
Height = LI.Height;
} else {
// For register units, the def latency is not included because we don't
// know the def yet.
RegUnits[LI.Reg].Cycle = LI.Height;
}
}
}
// Go through the trace blocks in bottom-up order.
SmallVector<DataDep, 8> Deps;
for (;!Stack.empty(); Stack.pop_back()) {
MBB = Stack.back();
DEBUG(dbgs() << "Heights for BB#" << MBB->getNumber() << ":\n");
TraceBlockInfo &TBI = BlockInfo[MBB->getNumber()];
TBI.HasValidInstrHeights = true;
TBI.CriticalPath = 0;
DEBUG({
dbgs() << format("%7u Instructions\n", TBI.InstrHeight);
ArrayRef<unsigned> PRHeights = getProcResourceHeights(MBB->getNumber());
for (unsigned K = 0; K != PRHeights.size(); ++K)
if (PRHeights[K]) {
unsigned Factor = MTM.SchedModel.getResourceFactor(K);
dbgs() << format("%6uc @ ", MTM.getCycles(PRHeights[K]))
<< MTM.SchedModel.getProcResource(K)->Name << " ("
<< PRHeights[K]/Factor << " ops x" << Factor << ")\n";
}
});
// Get dependencies from PHIs in the trace successor.
const MachineBasicBlock *Succ = TBI.Succ;
// If MBB is the last block in the trace, and it has a back-edge to the
// loop header, get loop-carried dependencies from PHIs in the header. For
// that purpose, pretend that all the loop header PHIs have height 0.
if (!Succ)
if (const MachineLoop *Loop = getLoopFor(MBB))
if (MBB->isSuccessor(Loop->getHeader()))
Succ = Loop->getHeader();
if (Succ) {
for (const auto &PHI : *Succ) {
if (!PHI.isPHI())
break;
Deps.clear();
getPHIDeps(PHI, Deps, MBB, MTM.MRI);
if (!Deps.empty()) {
// Loop header PHI heights are all 0.
unsigned Height = TBI.Succ ? Cycles.lookup(&PHI).Height : 0;
DEBUG(dbgs() << "pred\t" << Height << '\t' << PHI);
if (pushDepHeight(Deps.front(), PHI, Height, Heights, MTM.SchedModel,
MTM.TII))
addLiveIns(Deps.front().DefMI, Deps.front().DefOp, Stack);
}
}
}
// Go through the block backwards.
for (MachineBasicBlock::const_iterator BI = MBB->end(), BB = MBB->begin();
BI != BB;) {
const MachineInstr &MI = *--BI;
// Find the MI height as determined by virtual register uses in the
// trace below.
unsigned Cycle = 0;
MIHeightMap::iterator HeightI = Heights.find(&MI);
if (HeightI != Heights.end()) {
Cycle = HeightI->second;
// We won't be seeing any more MI uses.
Heights.erase(HeightI);
}
// Don't process PHI deps. They depend on the specific predecessor, and
// we'll get them when visiting the predecessor.
Deps.clear();
bool HasPhysRegs = !MI.isPHI() && getDataDeps(MI, Deps, MTM.MRI);
// There may also be regunit dependencies to include in the height.
if (HasPhysRegs)
Cycle = updatePhysDepsUpwards(MI, Cycle, RegUnits, MTM.SchedModel,
MTM.TII, MTM.TRI);
// Update the required height of any virtual registers read by MI.
for (const DataDep &Dep : Deps)
if (pushDepHeight(Dep, MI, Cycle, Heights, MTM.SchedModel, MTM.TII))
addLiveIns(Dep.DefMI, Dep.DefOp, Stack);
InstrCycles &MICycles = Cycles[&MI];
MICycles.Height = Cycle;
if (!TBI.HasValidInstrDepths) {
DEBUG(dbgs() << Cycle << '\t' << MI);
continue;
}
// Update critical path length.
TBI.CriticalPath = std::max(TBI.CriticalPath, Cycle + MICycles.Depth);
DEBUG(dbgs() << TBI.CriticalPath << '\t' << Cycle << '\t' << MI);
}
// Update virtual live-in heights. They were added by addLiveIns() with a 0
// height because the final height isn't known until now.
DEBUG(dbgs() << "BB#" << MBB->getNumber() << " Live-ins:");
for (LiveInReg &LIR : TBI.LiveIns) {
const MachineInstr *DefMI = MTM.MRI->getVRegDef(LIR.Reg);
LIR.Height = Heights.lookup(DefMI);
DEBUG(dbgs() << ' ' << printReg(LIR.Reg) << '@' << LIR.Height);
}
// Transfer the live regunits to the live-in list.
for (SparseSet<LiveRegUnit>::const_iterator
RI = RegUnits.begin(), RE = RegUnits.end(); RI != RE; ++RI) {
TBI.LiveIns.push_back(LiveInReg(RI->RegUnit, RI->Cycle));
DEBUG(dbgs() << ' ' << printRegUnit(RI->RegUnit, MTM.TRI)
<< '@' << RI->Cycle);
}
DEBUG(dbgs() << '\n');
if (!TBI.HasValidInstrDepths)
continue;
// Add live-ins to the critical path length.
TBI.CriticalPath = std::max(TBI.CriticalPath,
computeCrossBlockCriticalPath(TBI));
DEBUG(dbgs() << "Critical path: " << TBI.CriticalPath << '\n');
}
}
MachineTraceMetrics::Trace
MachineTraceMetrics::Ensemble::getTrace(const MachineBasicBlock *MBB) {
TraceBlockInfo &TBI = BlockInfo[MBB->getNumber()];
if (!TBI.hasValidDepth() || !TBI.hasValidHeight())
computeTrace(MBB);
if (!TBI.HasValidInstrDepths)
computeInstrDepths(MBB);
if (!TBI.HasValidInstrHeights)
computeInstrHeights(MBB);
return Trace(*this, TBI);
}
unsigned
MachineTraceMetrics::Trace::getInstrSlack(const MachineInstr &MI) const {
assert(getBlockNum() == unsigned(MI.getParent()->getNumber()) &&
"MI must be in the trace center block");
InstrCycles Cyc = getInstrCycles(MI);
return getCriticalPath() - (Cyc.Depth + Cyc.Height);
}
unsigned
MachineTraceMetrics::Trace::getPHIDepth(const MachineInstr &PHI) const {
const MachineBasicBlock *MBB = TE.MTM.MF->getBlockNumbered(getBlockNum());
SmallVector<DataDep, 1> Deps;
getPHIDeps(PHI, Deps, MBB, TE.MTM.MRI);
assert(Deps.size() == 1 && "PHI doesn't have MBB as a predecessor");
DataDep &Dep = Deps.front();
unsigned DepCycle = getInstrCycles(*Dep.DefMI).Depth;
// Add latency if DefMI is a real instruction. Transients get latency 0.
if (!Dep.DefMI->isTransient())
DepCycle += TE.MTM.SchedModel.computeOperandLatency(Dep.DefMI, Dep.DefOp,
&PHI, Dep.UseOp);
return DepCycle;
}
/// When bottom is set include instructions in current block in estimate.
unsigned MachineTraceMetrics::Trace::getResourceDepth(bool Bottom) const {
// Find the limiting processor resource.
// Numbers have been pre-scaled to be comparable.
unsigned PRMax = 0;
ArrayRef<unsigned> PRDepths = TE.getProcResourceDepths(getBlockNum());
if (Bottom) {
ArrayRef<unsigned> PRCycles = TE.MTM.getProcResourceCycles(getBlockNum());
for (unsigned K = 0; K != PRDepths.size(); ++K)
PRMax = std::max(PRMax, PRDepths[K] + PRCycles[K]);
} else {
for (unsigned K = 0; K != PRDepths.size(); ++K)
PRMax = std::max(PRMax, PRDepths[K]);
}
// Convert to cycle count.
PRMax = TE.MTM.getCycles(PRMax);
/// All instructions before current block
unsigned Instrs = TBI.InstrDepth;
// plus instructions in current block
if (Bottom)
Instrs += TE.MTM.BlockInfo[getBlockNum()].InstrCount;
if (unsigned IW = TE.MTM.SchedModel.getIssueWidth())
Instrs /= IW;
// Assume issue width 1 without a schedule model.
return std::max(Instrs, PRMax);
}
unsigned MachineTraceMetrics::Trace::getResourceLength(
ArrayRef<const MachineBasicBlock *> Extrablocks,
ArrayRef<const MCSchedClassDesc *> ExtraInstrs,
ArrayRef<const MCSchedClassDesc *> RemoveInstrs) const {
// Add up resources above and below the center block.
ArrayRef<unsigned> PRDepths = TE.getProcResourceDepths(getBlockNum());
ArrayRef<unsigned> PRHeights = TE.getProcResourceHeights(getBlockNum());
unsigned PRMax = 0;
// Capture computing cycles from extra instructions
auto extraCycles = [this](ArrayRef<const MCSchedClassDesc *> Instrs,
unsigned ResourceIdx)
->unsigned {
unsigned Cycles = 0;
for (const MCSchedClassDesc *SC : Instrs) {
if (!SC->isValid())
continue;
for (TargetSchedModel::ProcResIter
PI = TE.MTM.SchedModel.getWriteProcResBegin(SC),
PE = TE.MTM.SchedModel.getWriteProcResEnd(SC);
PI != PE; ++PI) {
if (PI->ProcResourceIdx != ResourceIdx)
continue;
Cycles +=
(PI->Cycles * TE.MTM.SchedModel.getResourceFactor(ResourceIdx));
}
}
return Cycles;
};
for (unsigned K = 0; K != PRDepths.size(); ++K) {
unsigned PRCycles = PRDepths[K] + PRHeights[K];
for (const MachineBasicBlock *MBB : Extrablocks)
PRCycles += TE.MTM.getProcResourceCycles(MBB->getNumber())[K];
PRCycles += extraCycles(ExtraInstrs, K);
PRCycles -= extraCycles(RemoveInstrs, K);
PRMax = std::max(PRMax, PRCycles);
}
// Convert to cycle count.
PRMax = TE.MTM.getCycles(PRMax);
// Instrs: #instructions in current trace outside current block.
unsigned Instrs = TBI.InstrDepth + TBI.InstrHeight;
// Add instruction count from the extra blocks.
for (const MachineBasicBlock *MBB : Extrablocks)
Instrs += TE.MTM.getResources(MBB)->InstrCount;
Instrs += ExtraInstrs.size();
Instrs -= RemoveInstrs.size();
if (unsigned IW = TE.MTM.SchedModel.getIssueWidth())
Instrs /= IW;
// Assume issue width 1 without a schedule model.
return std::max(Instrs, PRMax);
}
bool MachineTraceMetrics::Trace::isDepInTrace(const MachineInstr &DefMI,
const MachineInstr &UseMI) const {
if (DefMI.getParent() == UseMI.getParent())
return true;
const TraceBlockInfo &DepTBI = TE.BlockInfo[DefMI.getParent()->getNumber()];
const TraceBlockInfo &TBI = TE.BlockInfo[UseMI.getParent()->getNumber()];
return DepTBI.isUsefulDominator(TBI);
}
void MachineTraceMetrics::Ensemble::print(raw_ostream &OS) const {
OS << getName() << " ensemble:\n";
for (unsigned i = 0, e = BlockInfo.size(); i != e; ++i) {
OS << " BB#" << i << '\t';
BlockInfo[i].print(OS);
OS << '\n';
}
}
void MachineTraceMetrics::TraceBlockInfo::print(raw_ostream &OS) const {
if (hasValidDepth()) {
OS << "depth=" << InstrDepth;
if (Pred)
OS << " pred=BB#" << Pred->getNumber();
else
OS << " pred=null";
OS << " head=BB#" << Head;
if (HasValidInstrDepths)
OS << " +instrs";
} else
OS << "depth invalid";
OS << ", ";
if (hasValidHeight()) {
OS << "height=" << InstrHeight;
if (Succ)
OS << " succ=BB#" << Succ->getNumber();
else
OS << " succ=null";
OS << " tail=BB#" << Tail;
if (HasValidInstrHeights)
OS << " +instrs";
} else
OS << "height invalid";
if (HasValidInstrDepths && HasValidInstrHeights)
OS << ", crit=" << CriticalPath;
}
void MachineTraceMetrics::Trace::print(raw_ostream &OS) const {
unsigned MBBNum = &TBI - &TE.BlockInfo[0];
OS << TE.getName() << " trace BB#" << TBI.Head << " --> BB#" << MBBNum
<< " --> BB#" << TBI.Tail << ':';
if (TBI.hasValidHeight() && TBI.hasValidDepth())
OS << ' ' << getInstrCount() << " instrs.";
if (TBI.HasValidInstrDepths && TBI.HasValidInstrHeights)
OS << ' ' << TBI.CriticalPath << " cycles.";
const MachineTraceMetrics::TraceBlockInfo *Block = &TBI;
OS << "\nBB#" << MBBNum;
while (Block->hasValidDepth() && Block->Pred) {
unsigned Num = Block->Pred->getNumber();
OS << " <- BB#" << Num;
Block = &TE.BlockInfo[Num];
}
Block = &TBI;
OS << "\n ";
while (Block->hasValidHeight() && Block->Succ) {
unsigned Num = Block->Succ->getNumber();
OS << " -> BB#" << Num;
Block = &TE.BlockInfo[Num];
}
OS << '\n';
}
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