[llvm-mca] Move the logic that prints register file statistics to its own view. NFCI

Before this patch, the "BackendStatistics" view was responsible for printing the
register file usage (as well as many other statistics).

Now users can enable register file usage statistics using the command line flag
`-register-file-stats`. By default, the tool doesn't print register file
statistics.

llvm-svn: 329083

6 files changed, 186 insertions, 97 deletions

diff --git a/llvm/tools/llvm-mca/BackendStatistics.cpp b/llvm/tools/llvm-mca/BackendStatistics.cpp
index d89570b18ff..e40eb73480e 100644
--- a/llvm/tools/llvm-mca/BackendStatistics.cpp
+++ b/llvm/tools/llvm-mca/BackendStatistics.cpp
@@ -20,35 +20,11 @@ using namespace llvm;
 
 namespace mca {
 
-void BackendStatistics::initializeRegisterFileInfo() {
-  const MCSchedModel &SM = STI.getSchedModel();
-  RegisterFileUsage Empty = {0, 0, 0};
-  if (!SM.hasExtraProcessorInfo()) {
-    // Assume a single register file.
-    RegisterFiles.emplace_back(Empty);
-    return;
-  }
-
-  // Initialize a RegisterFileUsage for every user defined register file, plus
-  // the default register file which is always at index #0.
-  const MCExtraProcessorInfo &PI = SM.getExtraProcessorInfo();
-  // There is always an "InvalidRegisterFile" entry in tablegen. That entry can
-  // be skipped. If there are no user defined register files, then reserve a
-  // single entry for the default register file at index #0.
-  unsigned NumRegFiles = std::max(PI.NumRegisterFiles, 1U);
-  RegisterFiles.resize(NumRegFiles);
-  std::fill(RegisterFiles.begin(), RegisterFiles.end(), Empty);
-}
-
 void BackendStatistics::onInstructionEvent(const HWInstructionEvent &Event) {
   switch (Event.Type) {
   default:
     break;
   case HWInstructionEvent::Retired: {
-    const auto &RE = static_cast<const HWInstructionRetiredEvent &>(Event);
-    for (unsigned I = 0, E = RegisterFiles.size(); I < E; ++I)
-      RegisterFiles[I].CurrentlyUsedMappings -= RE.FreedPhysRegs[I];
-
     ++NumRetired;
     break;
   }
@@ -56,16 +32,6 @@ void BackendStatistics::onInstructionEvent(const HWInstructionEvent &Event) {
     ++NumIssued;
     break;
   case HWInstructionEvent::Dispatched: {
-    const auto &DE = static_cast<const HWInstructionDispatchedEvent &>(Event);
-    for (unsigned I = 0, E = RegisterFiles.size(); I < E; ++I) {
-      RegisterFileUsage &RFU = RegisterFiles[I];
-      unsigned NumUsedPhysRegs = DE.UsedPhysRegs[I];
-      RFU.CurrentlyUsedMappings += NumUsedPhysRegs;
-      RFU.TotalMappings += NumUsedPhysRegs;
-      RFU.MaxUsedMappings =
-          std::max(RFU.MaxUsedMappings, RFU.CurrentlyUsedMappings);
-    }
-
     ++NumDispatched;
   }
   }
@@ -150,46 +116,6 @@ void BackendStatistics::printSchedulerStatistics(llvm::raw_ostream &OS) const {
   OS << Buffer;
 }
 
-void BackendStatistics::printRATStatistics(raw_ostream &OS) const {
-  std::string Buffer;
-  raw_string_ostream TempStream(Buffer);
-
-  TempStream << "\n\nRegister File statistics:";
-  const RegisterFileUsage &GlobalUsage = RegisterFiles[0];
-  TempStream << "\nTotal number of mappings created:   "
-             << GlobalUsage.TotalMappings;
-  TempStream << "\nMax number of mappings used:        "
-             << GlobalUsage.MaxUsedMappings << '\n';
-
-  for (unsigned I = 1, E = RegisterFiles.size(); I < E; ++I) {
-    const RegisterFileUsage &RFU = RegisterFiles[I];
-    // Obtain the register file descriptor from the scheduling model.
-    assert(STI.getSchedModel().hasExtraProcessorInfo() &&
-           "Unable to find register file info!");
-    const MCExtraProcessorInfo &PI =
-        STI.getSchedModel().getExtraProcessorInfo();
-    assert(I <= PI.NumRegisterFiles && "Unexpected register file index!");
-    const MCRegisterFileDesc &RFDesc = PI.RegisterFiles[I];
-    // Skip invalid register files.
-    if (!RFDesc.NumPhysRegs)
-      continue;
-
-    TempStream << "\n*  Register File #" << I;
-    TempStream << " -- " << StringRef(RFDesc.Name) << ':';
-    TempStream << "\n   Number of physical registers:     ";
-    if (!RFDesc.NumPhysRegs)
-      TempStream << "unbounded";
-    else
-      TempStream << RFDesc.NumPhysRegs;
-    TempStream << "\n   Total number of mappings created: " << RFU.TotalMappings;
-    TempStream << "\n   Max number of mappings used:      "
-               << RFU.MaxUsedMappings << '\n';
-  }
-
-  TempStream.flush();
-  OS << Buffer;
-}
-
 void BackendStatistics::printDispatchStalls(raw_ostream &OS) const {
   std::string Buffer;
   raw_string_ostream TempStream(Buffer);
diff --git a/llvm/tools/llvm-mca/BackendStatistics.h b/llvm/tools/llvm-mca/BackendStatistics.h
index c3cec95f8df..7de38b45a7d 100644
--- a/llvm/tools/llvm-mca/BackendStatistics.h
+++ b/llvm/tools/llvm-mca/BackendStatistics.h
@@ -23,11 +23,6 @@
 /// GROUP   - Static restrictions on the dispatch group: 0
 ///
 ///
-/// Register Alias Table:
-/// Total number of mappings created: 210
-/// Max number of mappings used:      35
-///
-///
 /// Dispatch Logic - number of cycles where we saw N instructions dispatched:
 /// [# dispatched], [# cycles]
 ///  0,              15  (11.5%)
@@ -61,7 +56,6 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/MC/MCSubtargetInfo.h"
-#include "llvm/Support/raw_ostream.h"
 
 namespace mca {
 
@@ -102,24 +96,11 @@ class BackendStatistics : public View {
     NumRetired = 0;
   }
 
-  // Used to track the number of physical registers used in a register file.
-  struct RegisterFileUsage {
-    unsigned TotalMappings;
-    unsigned MaxUsedMappings;
-    unsigned CurrentlyUsedMappings;
-  };
-
-  // There is one entry for each register file implemented by the processor.
-  llvm::SmallVector<RegisterFileUsage, 4> RegisterFiles;
-
-  void initializeRegisterFileInfo();
-
   void printRetireUnitStatistics(llvm::raw_ostream &OS) const;
   void printDispatchUnitStatistics(llvm::raw_ostream &OS) const;
   void printSchedulerStatistics(llvm::raw_ostream &OS) const;
 
   void printDispatchStalls(llvm::raw_ostream &OS) const;
-  void printRATStatistics(llvm::raw_ostream &OS) const;
   void printRCUStatistics(llvm::raw_ostream &OS, const Histogram &Histogram,
                           unsigned Cycles) const;
   void printDispatchUnitUsage(llvm::raw_ostream &OS, const Histogram &Stats,
@@ -132,9 +113,7 @@ class BackendStatistics : public View {
 public:
   BackendStatistics(const llvm::MCSubtargetInfo &sti)
       : STI(sti), NumDispatched(0), NumIssued(0), NumRetired(0), NumCycles(0),
-        HWStalls(HWStallEvent::LastGenericEvent) {
-    initializeRegisterFileInfo();
-  }
+        HWStalls(HWStallEvent::LastGenericEvent) { }
 
   void onInstructionEvent(const HWInstructionEvent &Event) override;
 
@@ -157,7 +136,6 @@ public:
 
   void printView(llvm::raw_ostream &OS) const override {
     printDispatchStalls(OS);
-    printRATStatistics(OS);
     printDispatchUnitStatistics(OS);
     printSchedulerStatistics(OS);
     printRetireUnitStatistics(OS);
diff --git a/llvm/tools/llvm-mca/CMakeLists.txt b/llvm/tools/llvm-mca/CMakeLists.txt
index 36af64c0bd8..2964fde0309 100644
--- a/llvm/tools/llvm-mca/CMakeLists.txt
+++ b/llvm/tools/llvm-mca/CMakeLists.txt
@@ -21,6 +21,7 @@ add_llvm_tool(llvm-mca
   InstructionTables.cpp
   LSUnit.cpp
   llvm-mca.cpp
+  RegisterFileStatistics.cpp
   ResourcePressureView.cpp
   Scheduler.cpp
   Support.cpp
diff --git a/llvm/tools/llvm-mca/RegisterFileStatistics.cpp b/llvm/tools/llvm-mca/RegisterFileStatistics.cpp
new file mode 100644
index 00000000000..46302bf41b2
--- /dev/null
+++ b/llvm/tools/llvm-mca/RegisterFileStatistics.cpp
@@ -0,0 +1,108 @@
+//===--------------------- RegisterFileStatistics.cpp -----------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+/// \file
+///
+/// This file implements the RegisterFileStatistics interface.
+///
+//===----------------------------------------------------------------------===//
+
+#include "RegisterFileStatistics.h"
+#include "llvm/Support/Format.h"
+
+using namespace llvm;
+
+namespace mca {
+
+void RegisterFileStatistics::initializeRegisterFileInfo() {
+  const MCSchedModel &SM = STI.getSchedModel();
+  RegisterFileUsage Empty = {0, 0, 0};
+  if (!SM.hasExtraProcessorInfo()) {
+    // Assume a single register file.
+    RegisterFiles.emplace_back(Empty);
+    return;
+  }
+
+  // Initialize a RegisterFileUsage for every user defined register file, plus
+  // the default register file which is always at index #0.
+  const MCExtraProcessorInfo &PI = SM.getExtraProcessorInfo();
+  // There is always an "InvalidRegisterFile" entry in tablegen. That entry can
+  // be skipped. If there are no user defined register files, then reserve a
+  // single entry for the default register file at index #0.
+  unsigned NumRegFiles = std::max(PI.NumRegisterFiles, 1U);
+  RegisterFiles.resize(NumRegFiles);
+  std::fill(RegisterFiles.begin(), RegisterFiles.end(), Empty);
+}
+
+void RegisterFileStatistics::onInstructionEvent(
+    const HWInstructionEvent &Event) {
+  switch (Event.Type) {
+  default:
+    break;
+  case HWInstructionEvent::Retired: {
+    const auto &RE = static_cast<const HWInstructionRetiredEvent &>(Event);
+    for (unsigned I = 0, E = RegisterFiles.size(); I < E; ++I)
+      RegisterFiles[I].CurrentlyUsedMappings -= RE.FreedPhysRegs[I];
+    break;
+  }
+  case HWInstructionEvent::Dispatched: {
+    const auto &DE = static_cast<const HWInstructionDispatchedEvent &>(Event);
+    for (unsigned I = 0, E = RegisterFiles.size(); I < E; ++I) {
+      RegisterFileUsage &RFU = RegisterFiles[I];
+      unsigned NumUsedPhysRegs = DE.UsedPhysRegs[I];
+      RFU.CurrentlyUsedMappings += NumUsedPhysRegs;
+      RFU.TotalMappings += NumUsedPhysRegs;
+      RFU.MaxUsedMappings =
+          std::max(RFU.MaxUsedMappings, RFU.CurrentlyUsedMappings);
+    }
+  }
+  }
+}
+
+void RegisterFileStatistics::printView(raw_ostream &OS) const {
+  std::string Buffer;
+  raw_string_ostream TempStream(Buffer);
+
+  TempStream << "\n\nRegister File statistics:";
+  const RegisterFileUsage &GlobalUsage = RegisterFiles[0];
+  TempStream << "\nTotal number of mappings created:    "
+             << GlobalUsage.TotalMappings;
+  TempStream << "\nMax number of mappings used:         "
+             << GlobalUsage.MaxUsedMappings << '\n';
+
+  for (unsigned I = 1, E = RegisterFiles.size(); I < E; ++I) {
+    const RegisterFileUsage &RFU = RegisterFiles[I];
+    // Obtain the register file descriptor from the scheduling model.
+    assert(STI.getSchedModel().hasExtraProcessorInfo() &&
+           "Unable to find register file info!");
+    const MCExtraProcessorInfo &PI =
+        STI.getSchedModel().getExtraProcessorInfo();
+    assert(I <= PI.NumRegisterFiles && "Unexpected register file index!");
+    const MCRegisterFileDesc &RFDesc = PI.RegisterFiles[I];
+    // Skip invalid register files.
+    if (!RFDesc.NumPhysRegs)
+      continue;
+
+    TempStream << "\n*  Register File #" << I;
+    TempStream << " -- " << StringRef(RFDesc.Name) << ':';
+    TempStream << "\n   Number of physical registers:     ";
+    if (!RFDesc.NumPhysRegs)
+      TempStream << "unbounded";
+    else
+      TempStream << RFDesc.NumPhysRegs;
+    TempStream << "\n   Total number of mappings created: "
+               << RFU.TotalMappings;
+    TempStream << "\n   Max number of mappings used:      "
+               << RFU.MaxUsedMappings << '\n';
+  }
+
+  TempStream.flush();
+  OS << Buffer;
+}
+
+} // namespace mca
diff --git a/llvm/tools/llvm-mca/RegisterFileStatistics.h b/llvm/tools/llvm-mca/RegisterFileStatistics.h
new file mode 100644
index 00000000000..d36b61ecd2b
--- /dev/null
+++ b/llvm/tools/llvm-mca/RegisterFileStatistics.h
@@ -0,0 +1,67 @@
+//===--------------------- RegisterFileStatistics.h -------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+/// \file
+///
+/// This view collects and prints register file usage statistics.
+///
+/// Example  (-mcpu=btver2):
+/// ========================
+///
+/// Register File statistics:
+/// Total number of mappings created:    6
+/// Max number of mappings used:         3
+///
+/// *  Register File #1 -- FpuPRF:
+///    Number of physical registers:     72
+///    Total number of mappings created: 0
+///    Max number of mappings used:      0
+///
+/// *  Register File #2 -- IntegerPRF:
+///    Number of physical registers:     64
+///    Total number of mappings created: 6
+///    Max number of mappings used:      3
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TOOLS_LLVM_MCA_REGISTERFILESTATISTICS_H
+#define LLVM_TOOLS_LLVM_MCA_REGISTERFILESTATISTICS_H
+
+#include "View.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/MC/MCSubtargetInfo.h"
+
+namespace mca {
+
+class RegisterFileStatistics : public View {
+  const llvm::MCSubtargetInfo &STI;
+
+  // Used to track the number of physical registers used in a register file.
+  struct RegisterFileUsage {
+    unsigned TotalMappings;
+    unsigned MaxUsedMappings;
+    unsigned CurrentlyUsedMappings;
+  };
+
+  // There is one entry for each register file implemented by the processor.
+  llvm::SmallVector<RegisterFileUsage, 4> RegisterFiles;
+
+  void initializeRegisterFileInfo();
+
+public:
+  RegisterFileStatistics(const llvm::MCSubtargetInfo &sti) : STI(sti) {
+    initializeRegisterFileInfo();
+  }
+
+  void onInstructionEvent(const HWInstructionEvent &Event) override;
+
+  void printView(llvm::raw_ostream &OS) const override;
+};
+} // namespace mca
+
+#endif
diff --git a/llvm/tools/llvm-mca/llvm-mca.cpp b/llvm/tools/llvm-mca/llvm-mca.cpp
index 49d50476354..7ad31df3ce8 100644
--- a/llvm/tools/llvm-mca/llvm-mca.cpp
+++ b/llvm/tools/llvm-mca/llvm-mca.cpp
@@ -25,6 +25,7 @@
 #include "BackendStatistics.h"
 #include "InstructionInfoView.h"
 #include "InstructionTables.h"
+#include "RegisterFileStatistics.h"
 #include "ResourcePressureView.h"
 #include "SummaryView.h"
 #include "TimelineView.h"
@@ -92,6 +93,11 @@ static cl::opt<unsigned>
                      cl::init(0));
 
 static cl::opt<bool>
+    PrintRegisterFileStats("register-file-stats",
+                           cl::desc("Print register file statistics"),
+                           cl::init(false));
+
+static cl::opt<bool>
     PrintResourcePressureView("resource-pressure",
                               cl::desc("Print the resource pressure view"),
                               cl::init(true));
@@ -370,6 +376,9 @@ int main(int argc, char **argv) {
   if (PrintModeVerbose)
     Printer->addView(llvm::make_unique<mca::BackendStatistics>(*STI));
 
+  if (PrintRegisterFileStats)
+    Printer->addView(llvm::make_unique<mca::RegisterFileStatistics>(*STI));
+
   if (PrintResourcePressureView)
     Printer->addView(
         llvm::make_unique<mca::ResourcePressureView>(*STI, *IP, *S));