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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161711 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 42 insertions, 0 deletions

diff --git a/lib/CodeGen/MachineTraceMetrics.cpp b/lib/CodeGen/MachineTraceMetrics.cpp
index c6a6d58ec2..fc858be166 100644
--- a/lib/CodeGen/MachineTraceMetrics.cpp
+++ b/lib/CodeGen/MachineTraceMetrics.cpp
@@ -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) {
diff --git a/lib/CodeGen/MachineTraceMetrics.h b/lib/CodeGen/MachineTraceMetrics.h
index 4f39aca490..c5b86f31db 100644
--- a/lib/CodeGen/MachineTraceMetrics.h
+++ b/lib/CodeGen/MachineTraceMetrics.h
@@ -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