MC: Remove the copy of MCSchedModel in MCSubtargetInfo

`MCSchedModel` is large.  Make `MCSchedModel::GetDefaultSchedModel()`
return by-reference instead of by-value, so we can store a pointer in
`MCSubtargetInfo::CPUSchedModel` instead of a copy.

Note: since `MCSchedModel` is POD, this doesn't create a static
constructor.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241947 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MCSchedule.h

@@ -224,25 +224,9 @@ struct MCSchedModel {
     return &SchedClassTable[SchedClassIdx];
   }
 
-  // /\brief Returns a default initialized model. Used for unknown processors.
+  /// Returns the default initialized model.
-  static MCSchedModel GetDefaultSchedModel() {
+  static const MCSchedModel &GetDefaultSchedModel() { return Default; }
-    MCSchedModel Ret = { DefaultIssueWidth,
+  static const MCSchedModel Default;
-                         DefaultMicroOpBufferSize,
-                         DefaultLoopMicroOpBufferSize,
-                         DefaultLoadLatency,
-                         DefaultHighLatency,
-                         DefaultMispredictPenalty,
-                         false,
-                         true,
-                         0,
-                         nullptr,
-                         nullptr,
-                         0,
-                         0,
-                         nullptr
-                       };
-    return Ret;
-  }
 };
 
 } // End llvm namespace

include/llvm/MC/MCSubtargetInfo.h

@@ -37,7 +37,7 @@ class MCSubtargetInfo {
   const MCWriteProcResEntry *WriteProcResTable;
   const MCWriteLatencyEntry *WriteLatencyTable;
   const MCReadAdvanceEntry *ReadAdvanceTable;
-  MCSchedModel CPUSchedModel;
+  const MCSchedModel *CPUSchedModel;
 
   const InstrStage *Stages;            // Instruction itinerary stages
   const unsigned *OperandCycles;       // Itinerary operand cycles
@@ -99,11 +99,10 @@ public:
 
   /// getSchedModelForCPU - Get the machine model of a CPU.
   ///
-  MCSchedModel getSchedModelForCPU(StringRef CPU) const;
+  const MCSchedModel &getSchedModelForCPU(StringRef CPU) const;
 
-  /// getSchedModel - Get the machine model for this subtarget's CPU.
+  /// Get the machine model for this subtarget's CPU.
-  ///
+  const MCSchedModel &getSchedModel() const { return *CPUSchedModel; }
-  const MCSchedModel &getSchedModel() const { return CPUSchedModel; }
 
   /// Return an iterator at the first process resource consumed by the given
   /// scheduling class.

lib/MC/CMakeLists.txt

@@ -28,6 +28,7 @@ add_llvm_library(LLVMMC
   MCObjectStreamer.cpp
   MCObjectWriter.cpp
   MCRegisterInfo.cpp
+  MCSchedule.cpp
   MCSection.cpp
   MCSectionCOFF.cpp
   MCSectionELF.cpp

lib/MC/MCSchedule.cpp

@@ -0,0 +1,33 @@
+//===- MCSchedule.cpp - 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 default scheduling model.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/MC/MCSchedule.h"
+
+using namespace llvm;
+
+static_assert(std::is_pod<MCSchedModel>::value,
+              "We shouldn't have a static constructor here");
+const MCSchedModel MCSchedModel::Default = {DefaultIssueWidth,
+                                            DefaultMicroOpBufferSize,
+                                            DefaultLoopMicroOpBufferSize,
+                                            DefaultLoadLatency,
+                                            DefaultHighLatency,
+                                            DefaultMispredictPenalty,
+                                            false,
+                                            true,
+                                            0,
+                                            nullptr,
+                                            nullptr,
+                                            0,
+                                            0,
+                                            nullptr};

lib/MC/MCSubtargetInfo.cpp

@@ -29,9 +29,9 @@ MCSubtargetInfo::InitMCProcessorInfo(StringRef CPU, StringRef FS) {
 void
 MCSubtargetInfo::InitCPUSchedModel(StringRef CPU) {
   if (!CPU.empty())
-    CPUSchedModel = getSchedModelForCPU(CPU);
+    CPUSchedModel = &getSchedModelForCPU(CPU);
   else
-    CPUSchedModel = MCSchedModel::GetDefaultSchedModel();
+    CPUSchedModel = &MCSchedModel::GetDefaultSchedModel();
 }
 
 void MCSubtargetInfo::InitMCSubtargetInfo(
@@ -82,8 +82,7 @@ FeatureBitset MCSubtargetInfo::ApplyFeatureFlag(StringRef FS) {
   return FeatureBits;
 }
 
-MCSchedModel
+const MCSchedModel &MCSubtargetInfo::getSchedModelForCPU(StringRef CPU) const {
-MCSubtargetInfo::getSchedModelForCPU(StringRef CPU) const {
   assert(ProcSchedModels && "Processor machine model not available!");
 
   unsigned NumProcs = ProcDesc.size();
@@ -116,6 +115,6 @@ MCSubtargetInfo::getInstrItineraryForCPU(StringRef CPU) const {
 
 /// Initialize an InstrItineraryData instance.
 void MCSubtargetInfo::initInstrItins(InstrItineraryData &InstrItins) const {
-  InstrItins =
+  InstrItins = InstrItineraryData(getSchedModel(), Stages, OperandCycles,
-    InstrItineraryData(CPUSchedModel, Stages, OperandCycles, ForwardingPaths);
+                                  ForwardingPaths);
 }