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Add more trace query functions. 

Trace::getResourceLength() computes the number of cycles required to
execute the trace when ignoring data dependencies. The number can be
compared to the critical path to estimate the trace ILP.

Trace::getPHIDepth() computes the data dependency depth of a PHI in a
trace successor that isn't necessarily part of the trace.

llvm-svn: 161711
This commit is contained in:
Jakob Stoklund Olesen 2012-08-10 22:27:27 +00:00
parent 02e5309b35
commit 3484420927
2 changed files with 42 additions and 0 deletions
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29
llvm/lib/CodeGen/MachineTraceMetrics.cpp
View File

@ -1044,6 +1044,23 @@ MachineTraceMetrics::Trace::getInstrSlack(const MachineInstr *MI) const {
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.TII->computeOperandLatency(TE.MTM.ItinData,
Dep.DefMI, Dep.DefOp,
PHI, Dep.UseOp,
/* FindMin = */ false);
return DepCycle;
}
unsigned MachineTraceMetrics::Trace::getResourceDepth(bool Bottom) const {
// For now, we compute the resource depth from instruction count / issue
// width. Eventually, we should compute resource depth per functional unit
@ -1058,6 +1075,18 @@ unsigned MachineTraceMetrics::Trace::getResourceDepth(bool Bottom) const {
return Instrs;
}
unsigned MachineTraceMetrics::Trace::
getResourceLength(ArrayRef<const MachineBasicBlock*> Extrablocks) const {
unsigned Instrs = TBI.InstrDepth + TBI.InstrHeight;
for (unsigned i = 0, e = Extrablocks.size(); i != e; ++i)
Instrs += TE.MTM.getResources(Extrablocks[i])->InstrCount;
if (const MCSchedModel *Model = TE.MTM.ItinData->SchedModel)
if (Model->IssueWidth != 0)
return Instrs / Model->IssueWidth;
// Assume issue width 1 without a schedule model.
return Instrs;
}
void MachineTraceMetrics::Ensemble::print(raw_ostream &OS) const {
OS << getName() << " ensemble:\n";
for (unsigned i = 0, e = BlockInfo.size(); i != e; ++i) {

13
llvm/lib/CodeGen/MachineTraceMetrics.h
View File

@ -226,6 +226,15 @@ public:
/// When Bottom is set, instructions in the trace center block are included.
unsigned getResourceDepth(bool Bottom) const;
/// Return the resource length of the trace. This is the number of cycles
/// required to execute the instructions in the trace if they were all
/// independent, exposing the maximum instruction-level parallelism.
///
/// Any blocks in Extrablocks are included as if they were part of the
/// trace.
unsigned getResourceLength(ArrayRef<const MachineBasicBlock*> Extrablocks =
ArrayRef<const MachineBasicBlock*>()) const;
/// Return the length of the (data dependency) critical path through the
/// trace.
unsigned getCriticalPath() const { return TBI.CriticalPath; }
@ -241,6 +250,10 @@ public:
/// before the critical path becomes longer.
/// MI must be an instruction in the trace center block.
unsigned getInstrSlack(const MachineInstr *MI) const;
/// Return the Depth of a PHI instruction in a trace center block successor.
/// The PHI does not have to be part of the trace.
unsigned getPHIDepth(const MachineInstr *PHI) const;
};
/// A trace ensemble is a collection of traces selected using the same