Vendor import of llvm trunk r161861:

http://llvm.org/svn/llvm-project/llvm/trunk@161861

1 files changed, 114 insertions, 0 deletions

diff --git a/include/llvm/MC/MCSchedule.h b/include/llvm/MC/MCSchedule.h
new file mode 100644
index 0000000..3b1cdf1
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+++ b/include/llvm/MC/MCSchedule.h
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+//===-- llvm/MC/MCSchedule.h - Scheduling -----------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the classes used to describe a subtarget's machine model
+// for scheduling and other instruction cost heuristics.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_MC_MCSCHEDMODEL_H
+#define LLVM_MC_MCSCHEDMODEL_H
+
+#include "llvm/Support/DataTypes.h"
+
+namespace llvm {
+
+struct InstrItinerary;
+
+/// Machine model for scheduling, bundling, and heuristics.
+///
+/// The machine model directly provides basic information about the
+/// microarchitecture to the scheduler in the form of properties. It also
+/// optionally refers to scheduler resources tables and itinerary
+/// tables. Scheduler resources tables model the latency and cost for each
+/// instruction type. Itinerary tables are an independant mechanism that
+/// provides a detailed reservation table describing each cycle of instruction
+/// execution. Subtargets may define any or all of the above categories of data
+/// depending on the type of CPU and selected scheduler.
+class MCSchedModel {
+public:
+  static MCSchedModel DefaultSchedModel; // For unknown processors.
+
+  // IssueWidth is the maximum number of instructions that may be scheduled in
+  // the same per-cycle group.
+  unsigned IssueWidth;
+  static const unsigned DefaultIssueWidth = 1;
+
+  // MinLatency is the minimum latency between a register write
+  // followed by a data dependent read. This determines which
+  // instructions may be scheduled in the same per-cycle group. This
+  // is distinct from *expected* latency, which determines the likely
+  // critical path but does not guarantee a pipeline
+  // hazard. MinLatency can always be overridden by the number of
+  // InstrStage cycles.
+  //
+  // (-1) Standard in-order processor.
+  //      Use InstrItinerary OperandCycles as MinLatency.
+  //      If no OperandCycles exist, then use the cycle of the last InstrStage.
+  //
+  //  (0) Out-of-order processor, or in-order with bundled dependencies.
+  //      RAW dependencies may be dispatched in the same cycle.
+  //      Optional InstrItinerary OperandCycles provides expected latency.
+  //
+  // (>0) In-order processor with variable latencies.
+  //      Use the greater of this value or the cycle of the last InstrStage.
+  //      Optional InstrItinerary OperandCycles provides expected latency.
+  //      TODO: can't yet specify both min and expected latency per operand.
+  int MinLatency;
+  static const unsigned DefaultMinLatency = -1;
+
+  // LoadLatency is the expected latency of load instructions.
+  //
+  // If MinLatency >= 0, this may be overriden for individual load opcodes by
+  // InstrItinerary OperandCycles.
+  unsigned LoadLatency;
+  static const unsigned DefaultLoadLatency = 4;
+
+  // HighLatency is the expected latency of "very high latency" operations.
+  // See TargetInstrInfo::isHighLatencyDef().
+  // By default, this is set to an arbitrarily high number of cycles
+  // likely to have some impact on scheduling heuristics.
+  // If MinLatency >= 0, this may be overriden by InstrItinData OperandCycles.
+  unsigned HighLatency;
+  static const unsigned DefaultHighLatency = 10;
+
+  // MispredictPenalty is the typical number of extra cycles the processor
+  // takes to recover from a branch misprediction.
+  unsigned MispredictPenalty;
+  static const unsigned DefaultMispredictPenalty = 10;
+
+private:
+  // TODO: Add a reference to proc resource types and sched resource tables.
+
+  // Instruction itinerary tables used by InstrItineraryData.
+  friend class InstrItineraryData;
+  const InstrItinerary *InstrItineraries;
+
+public:
+  // Default's must be specified as static const literals so that tablegenerated
+  // target code can use it in static initializers. The defaults need to be
+  // initialized in this default ctor because some clients directly instantiate
+  // MCSchedModel instead of using a generated itinerary.
+  MCSchedModel(): IssueWidth(DefaultIssueWidth),
+                  MinLatency(DefaultMinLatency),
+                  LoadLatency(DefaultLoadLatency),
+                  HighLatency(DefaultHighLatency),
+                  MispredictPenalty(DefaultMispredictPenalty),
+                  InstrItineraries(0) {}
+
+  // Table-gen driven ctor.
+  MCSchedModel(unsigned iw, int ml, unsigned ll, unsigned hl, unsigned mp,
+               const InstrItinerary *ii):
+    IssueWidth(iw), MinLatency(ml), LoadLatency(ll), HighLatency(hl),
+    MispredictPenalty(mp), InstrItineraries(ii){}
+};
+
+} // End llvm namespace
+
+#endif