[CodeGen] Extend Performance Counter to track per-scop information.

Previously, we would generate one performance counter for all scops.
Now, we generate both the old information, as well as a per-scop
performance counter to generate finer grained information.

This patch needed a way to generate a unique name for a `Scop`.
The start region, end region, and function name combined provides a
unique `Scop` name. So, `Scop` has a new public API to provide its start
and end region names.

Differential Revision: https://reviews.llvm.org/D33723

llvm-svn: 304528

polly/include/polly/CodeGen/PerfMonitor.h

@@ -25,8 +25,10 @@ class PerfMonitor {
 public:
   /// Create a new performance monitor.
   ///
+  /// @param S The scop for which to generate fine-grained performance
+  ///          monitoring information.
   /// @param M The module for which to generate the performance monitor.
-  PerfMonitor(llvm::Module *M);
+  PerfMonitor(const Scop &S, llvm::Module *M);
 
   /// Initialize the performance monitor.
   ///
@@ -48,12 +50,18 @@ private:
   llvm::Module *M;
   PollyIRBuilder Builder;
 
+  // The scop to profile against.
+  const Scop &S;
+
   /// Indicates if performance profiling is supported on this architecture.
   bool Supported;
 
   /// The cycle counter at the beginning of the program execution.
   llvm::Value *CyclesTotalStartPtr;
 
+  /// The total number of cycles spent in the current scop S.
+  llvm::Value *CyclesInCurrentScopPtr;
+
   /// The total number of cycles spent within scops.
   llvm::Value *CyclesInScopsPtr;
 
@@ -89,6 +97,12 @@ private:
   /// into the module (or obtain references to them if they already exist).
   void addGlobalVariables();
 
+  /// Add per-scop tracking to module.
+  ///
+  /// Insert the global variable which is used to track the number of cycles
+  /// this scop runs.
+  void addScopCounter();
+
   /// Get a reference to the intrinsic "i64 @llvm.x86.rdtscp(i8*)".
   ///
   /// The rdtscp function returns the current value of the processor's
@@ -126,6 +140,12 @@ private:
   /// This function finalizes the performance measurements and prints the
   /// results to stdout. It is expected to be registered with 'atexit()'.
   llvm::Function *insertFinalReporting();
+
+  /// Append Scop reporting data to "__polly_perf_final_reporting".
+  ///
+  /// This function appends the current scop (S)'s information to the final
+  /// printing function.
+  void AppendScopReporting();
 };
 } // namespace polly
 

polly/include/polly/ScopInfo.h

@@ -2329,6 +2329,14 @@ public:
   /// Check if the SCoP has been optimized by the scheduler.
   bool isOptimized() const { return IsOptimized; }
 
+  /// Get the name of the entry and exit blocks of this Scop.
+  ///
+  /// These along with the function name can uniquely identify a Scop.
+  ///
+  /// @return std::pair whose first element is the entry name & second element
+  ///         is the exit name.
+  std::pair<std::string, std::string> getEntryExitStr() const;
+
   /// Get the name of this Scop.
   std::string getNameStr() const;
 

polly/lib/Analysis/ScopInfo.cpp

@@ -4125,6 +4125,12 @@ std::string Scop::getInvalidContextStr() const {
 }
 
 std::string Scop::getNameStr() const {
+  std::string ExitName, EntryName;
+  std::tie(EntryName, ExitName) = getEntryExitStr();
+  return EntryName + "---" + ExitName;
+}
+
+std::pair<std::string, std::string> Scop::getEntryExitStr() const {
   std::string ExitName, EntryName;
   raw_string_ostream ExitStr(ExitName);
   raw_string_ostream EntryStr(EntryName);
@@ -4138,7 +4144,7 @@ std::string Scop::getNameStr() const {
   } else
     ExitName = "FunctionExit";
 
-  return EntryName + "---" + ExitName;
+  return std::make_pair(EntryName, ExitName);
 }
 
 __isl_give isl_set *Scop::getContext() const { return isl_set_copy(Context); }

polly/lib/CodeGen/CodeGeneration.cpp

@@ -184,7 +184,7 @@ static bool CodeGen(Scop &S, IslAstInfo &AI, LoopInfo &LI, DominatorTree &DT,
   IslNodeBuilder NodeBuilder(Builder, Annotator, DL, LI, SE, DT, S, StartBlock);
 
   if (PerfMonitoring) {
-    PerfMonitor P(EnteringBB->getParent()->getParent());
+    PerfMonitor P(S, EnteringBB->getParent()->getParent());
     P.initialize();
     P.insertRegionStart(SplitBlock->getTerminator());
 

polly/lib/CodeGen/PerfMonitor.cpp

@@ -11,8 +11,10 @@
 
 #include "polly/CodeGen/PerfMonitor.h"
 #include "polly/CodeGen/RuntimeDebugBuilder.h"
+#include "polly/ScopInfo.h"
 #include "llvm/ADT/Triple.h"
 #include "llvm/IR/Intrinsics.h"
+#include <sstream>
 
 using namespace llvm;
 using namespace polly;
@@ -60,51 +62,73 @@ Function *PerfMonitor::getRDTSCP() {
   return Intrinsic::getDeclaration(M, Intrinsic::x86_rdtscp);
 }
 
-PerfMonitor::PerfMonitor(Module *M) : M(M), Builder(M->getContext()) {
+PerfMonitor::PerfMonitor(const Scop &S, Module *M)
+    : M(M), Builder(M->getContext()), S(S) {
   if (Triple(M->getTargetTriple()).getArch() == llvm::Triple::x86_64)
     Supported = true;
   else
     Supported = false;
 }
 
+static void TryRegisterGlobal(Module *M, const char *Name,
+                              Constant *InitialValue, Value **Location) {
+  *Location = M->getGlobalVariable(Name);
+
+  if (!*Location)
+    *Location = new GlobalVariable(
+        *M, InitialValue->getType(), true, GlobalValue::WeakAnyLinkage,
+        InitialValue, Name, nullptr, GlobalVariable::InitialExecTLSModel);
+};
+
+// Generate a unique name that is usable as a LLVM name for a scop to name its
+// performance counter.
+static std::string GetScopUniqueVarname(const Scop &S) {
+  std::stringstream Name;
+  std::string EntryString, ExitString;
+  std::tie(EntryString, ExitString) = S.getEntryExitStr();
+
+  Name << "__polly_perf_cycles_in_" << std::string(S.getFunction().getName())
+       << "_from__" << EntryString << "__to__" << ExitString;
+  return Name.str();
+}
+
+void PerfMonitor::addScopCounter() {
+  const std::string varname = GetScopUniqueVarname(S);
+  TryRegisterGlobal(M, varname.c_str(), Builder.getInt64(0),
+                    &CyclesInCurrentScopPtr);
+}
+
 void PerfMonitor::addGlobalVariables() {
-  auto TryRegisterGlobal = [=](const char *Name, Constant *InitialValue,
-                               Value **Location) {
-    *Location = M->getGlobalVariable(Name);
-
-    if (!*Location)
-      *Location = new GlobalVariable(
-          *M, InitialValue->getType(), true, GlobalValue::WeakAnyLinkage,
-          InitialValue, Name, nullptr, GlobalVariable::InitialExecTLSModel);
-  };
-
-  TryRegisterGlobal("__polly_perf_cycles_total_start", Builder.getInt64(0),
+  TryRegisterGlobal(M, "__polly_perf_cycles_total_start", Builder.getInt64(0),
                     &CyclesTotalStartPtr);
 
-  TryRegisterGlobal("__polly_perf_initialized", Builder.getInt1(0),
+  TryRegisterGlobal(M, "__polly_perf_initialized", Builder.getInt1(0),
                     &AlreadyInitializedPtr);
 
-  TryRegisterGlobal("__polly_perf_cycles_in_scops", Builder.getInt64(0),
+  TryRegisterGlobal(M, "__polly_perf_cycles_in_scops", Builder.getInt64(0),
                     &CyclesInScopsPtr);
 
-  TryRegisterGlobal("__polly_perf_cycles_in_scop_start", Builder.getInt64(0),
+  TryRegisterGlobal(M, "__polly_perf_cycles_in_scop_start", Builder.getInt64(0),
                     &CyclesInScopStartPtr);
 
-  TryRegisterGlobal("__polly_perf_write_loation", Builder.getInt32(0),
+  TryRegisterGlobal(M, "__polly_perf_write_loation", Builder.getInt32(0),
                     &RDTSCPWriteLocation);
 }
 
 static const char *InitFunctionName = "__polly_perf_init";
 static const char *FinalReportingFunctionName = "__polly_perf_final";
 
+static BasicBlock *FinalStartBB = nullptr;
+static ReturnInst *ReturnFromFinal = nullptr;
+
 Function *PerfMonitor::insertFinalReporting() {
   // Create new function.
   GlobalValue::LinkageTypes Linkage = Function::WeakODRLinkage;
   FunctionType *Ty = FunctionType::get(Builder.getVoidTy(), {}, false);
   Function *ExitFn =
       Function::Create(Ty, Linkage, FinalReportingFunctionName, M);
-  BasicBlock *Start = BasicBlock::Create(M->getContext(), "start", ExitFn);
-  Builder.SetInsertPoint(Start);
+  FinalStartBB = BasicBlock::Create(M->getContext(), "start", ExitFn);
+  Builder.SetInsertPoint(FinalStartBB);
 
   if (!Supported) {
     RuntimeDebugBuilder::createCPUPrinter(
@@ -128,23 +152,42 @@ Function *PerfMonitor::insertFinalReporting() {
   RuntimeDebugBuilder::createCPUPrinter(Builder, "Total: ", CyclesTotal, "\n");
   RuntimeDebugBuilder::createCPUPrinter(Builder, "Scops: ", CyclesInScops,
                                         "\n");
-
-  // Finalize function.
-  Builder.CreateRetVoid();
+  ReturnFromFinal = Builder.CreateRetVoid();
   return ExitFn;
 }
 
+void PerfMonitor::AppendScopReporting() {
+  Builder.SetInsertPoint(FinalStartBB);
+  ReturnFromFinal->eraseFromParent();
+
+  Value *CyclesInCurrentScop =
+      Builder.CreateLoad(this->CyclesInCurrentScopPtr, true);
+  std::string EntryName, ExitName;
+  std::tie(EntryName, ExitName) = S.getEntryExitStr();
+
+  RuntimeDebugBuilder::createCPUPrinter(
+      Builder, "Scop(", S.getFunction().getName(), " |from: ", EntryName,
+      " |to: ", ExitName, "): ", CyclesInCurrentScop, "\n");
+
+  ReturnFromFinal = Builder.CreateRetVoid();
+}
+
+static Function *FinalReporting = nullptr;
+
 void PerfMonitor::initialize() {
   addGlobalVariables();
+  addScopCounter();
 
-  Function *F = M->getFunction(InitFunctionName);
-  if (F)
-    return;
+  // Ensure that we only add the final reporting function once.
+  // On later invocations, append to the reporting function.
+  if (!FinalReporting) {
+    FinalReporting = insertFinalReporting();
 
-  // initialize
-  Function *FinalReporting = insertFinalReporting();
-  Function *InitFn = insertInitFunction(FinalReporting);
-  addToGlobalConstructors(InitFn);
+    Function *InitFn = insertInitFunction(FinalReporting);
+    addToGlobalConstructors(InitFn);
+  }
+
+  AppendScopReporting();
 }
 
 Function *PerfMonitor::insertInitFunction(Function *FinalReporting) {
@@ -223,4 +266,8 @@ void PerfMonitor::insertRegionEnd(Instruction *InsertBefore) {
   Value *CyclesInScops = Builder.CreateLoad(CyclesInScopsPtr, true);
   CyclesInScops = Builder.CreateAdd(CyclesInScops, CyclesInScop);
   Builder.CreateStore(CyclesInScops, CyclesInScopsPtr, true);
+
+  Value *CyclesInCurrentScop = Builder.CreateLoad(CyclesInCurrentScopPtr, true);
+  CyclesInCurrentScop = Builder.CreateAdd(CyclesInCurrentScop, CyclesInScop);
+  Builder.CreateStore(CyclesInCurrentScop, CyclesInCurrentScopPtr, true);
 }

polly/test/Isl/CodeGen/perf_monitoring.ll

@@ -49,7 +49,6 @@ return:
 ; CHECK-NEXT:   %8 = load volatile i64, i64* @__polly_perf_cycles_in_scops
 ; CHECK-NEXT:   %9 = add i64 %8, %7
 ; CHECK-NEXT:   store volatile i64 %9, i64* @__polly_perf_cycles_in_scops
-; CHECK-NEXT:   br label %return
 
 
 ; CHECK:      define weak_odr void @__polly_perf_final() {
@@ -66,8 +65,6 @@ return:
 ; CHECK-NEXT:   %9 = call i32 @fflush(i8* null)
 ; CHECK-NEXT:   %10 = call i32 (...) @printf(i8* getelementptr inbounds ([8 x i8], [8 x i8]* @9, i32 0, i32 0), i8 addrspace(4)* getelementptr inbounds ([8 x i8], [8 x i8] addrspace(4)* @7, i32 0, i32 0), i64 %3, i8 addrspace(4)* getelementptr inbounds ([2 x i8], [2 x i8] addrspace(4)* @8, i32 0, i32 0))
 ; CHECK-NEXT:   %11 = call i32 @fflush(i8* null)
-; CHECK-NEXT:   ret void
-; CHECK-NEXT: }
 
 
 ; CHECK:      define weak_odr void @__polly_perf_init() {

polly/test/Isl/CodeGen/perf_monitoring_per_scop.ll

@@ -0,0 +1,100 @@
+; RUN: opt %loadPolly -polly-codegen -polly-codegen-perf-monitoring \
+; RUN:   -S < %s | FileCheck %s
+
+; void f(long A[], long N) {
+;   long i;
+;   if (true)
+;     for (i = 0; i < N; ++i)
+;       A[i] = i;
+; }
+; void g(long A[], long N) {
+;   long i;
+;   if (true)
+;     for (i = 0; i < N; ++i)
+;       A[i] = i;
+; }
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @f(i64* %A, i64 %N) nounwind {
+entry:
+  fence seq_cst
+  br label %next
+
+next:
+  br i1 true, label %for.i, label %return
+
+for.i:
+  %indvar = phi i64 [ 0, %next], [ %indvar.next, %for.i ]
+  %scevgep = getelementptr i64, i64* %A, i64 %indvar
+  store i64 %indvar, i64* %scevgep
+  %indvar.next = add nsw i64 %indvar, 1
+  %exitcond = icmp eq i64 %indvar.next, %N
+  br i1 %exitcond, label %return, label %for.i
+
+return:
+  fence seq_cst
+  ret void
+}
+
+
+define void @g(i64* %A, i64 %N) nounwind {
+entry:
+  fence seq_cst
+  br label %next
+
+next:
+  br i1 true, label %for.i, label %return
+
+for.i:
+  %indvar = phi i64 [ 0, %next], [ %indvar.next, %for.i ]
+  %scevgep = getelementptr i64, i64* %A, i64 %indvar
+  store i64 %indvar, i64* %scevgep
+  %indvar.next = add nsw i64 %indvar, 1
+  %exitcond = icmp eq i64 %indvar.next, %N
+  br i1 %exitcond, label %return, label %for.i
+
+return:
+  fence seq_cst
+  ret void
+}
+
+; Declaration of globals
+; CHECK: @"__polly_perf_cycles_in_f_from__%next__to__%polly.merge_new_and_old" = weak thread_local(initialexec) constant i64 0
+; CHECK: @"__polly_perf_cycles_in_g_from__%next__to__%polly.merge_new_and_old" = weak thread_local(initialexec) constant i64 0
+
+; Bumping up counter in f
+; CHECK:      polly.merge_new_and_old:                          ; preds = %polly.exiting, %return.region_exiting
+; CHECK-NEXT:   %5 = load volatile i64, i64* @__polly_perf_cycles_in_scop_start
+; CHECK-NEXT:   %6 = call i64 @llvm.x86.rdtscp(i8* bitcast (i32* @__polly_perf_write_loation to i8*))
+; CHECK-NEXT:   %7 = sub i64 %6, %5
+; CHECK-NEXT:   %8 = load volatile i64, i64* @__polly_perf_cycles_in_scops
+; CHECK-NEXT:   %9 = add i64 %8, %7
+; CHECK-NEXT:   store volatile i64 %9, i64* @__polly_perf_cycles_in_scops
+; CHECK-NEXT:   %10 = load volatile i64, i64* @"__polly_perf_cycles_in_f_from__%next__to__%polly.merge_new_and_old"
+; CHECK-NEXT:   %11 = add i64 %10, %7
+; CHECK-NEXT:   store volatile i64 %11, i64* @"__polly_perf_cycles_in_f_from__%next__to__%polly.merge_new_and_old"
+; CHECK-NEXT:   br label %return
+
+; Bumping up counter in g
+; CHECK:       polly.merge_new_and_old:                          ; preds = %polly.exiting, %return.region_exiting
+; CHECK-NEXT:   %5 = load volatile i64, i64* @__polly_perf_cycles_in_scop_start
+; CHECK-NEXT:   %6 = call i64 @llvm.x86.rdtscp(i8* bitcast (i32* @__polly_perf_write_loation to i8*))
+; CHECK-NEXT:   %7 = sub i64 %6, %5
+; CHECK-NEXT:   %8 = load volatile i64, i64* @__polly_perf_cycles_in_scops
+; CHECK-NEXT:   %9 = add i64 %8, %7
+; CHECK-NEXT:   store volatile i64 %9, i64* @__polly_perf_cycles_in_scops
+; CHECK-NEXT:   %10 = load volatile i64, i64* @"__polly_perf_cycles_in_g_from__%next__to__%polly.merge_new_and_old"
+; CHECK-NEXT:   %11 = add i64 %10, %7
+; CHECK-NEXT:   store volatile i64 %11, i64* @"__polly_perf_cycles_in_g_from__%next__to__%polly.merge_new_and_old"
+; CHECK-NEXT:   br label %return
+
+; Final reporting prints
+; CHECK:       %12 = load volatile i64, i64* @"__polly_perf_cycles_in_f_from__%next__to__%polly.merge_new_and_old"
+; CHECK-NEXT:  %13 = call i32 (...) @printf(i8* getelementptr inbounds ([20 x i8], [20 x i8]* @18, i32 0, i32 0), i8 addrspace(4)* getelementptr inbounds ([6 x i8], [6 x i8] addrspace(4)* @10, i32 0, i32 0), i8 addrspace(4)* getelementptr inbounds ([2 x i8], [2 x i8] addrspace(4)* @11, i32 0, i32 0), i8 addrspace(4)* getelementptr inbounds ([9 x i8], [9 x i8] addrspace(4)* @12, i32 0, i32 0), i8 addrspace(4)* getelementptr inbounds ([6 x i8], [6 x i8] addrspace(4)* @13, i32 0, i32 0), i8 addrspace(4)* getelementptr inbounds ([7 x i8], [7 x i8] addrspace(4)* @14, i32 0, i32 0), i8 addrspace(4)* getelementptr inbounds ([25 x i8], [25 x i8] addrspace(4)* @15, i32 0, i32 0), i8 addrspace(4)* getelementptr inbounds ([4 x i8], [4 x i8] addrspace(4)* @16, i32 0, i32 0), i64 %12, i8 addrspace(4)* getelementptr inbounds ([2 x i8], [2 x i8] addrspace(4)* @17, i32 0, i32 0))
+; CHECK-NEXT:  %14 = call i32 @fflush(i8* null)
+; CHECK-NEXT:  %15 = load volatile i64, i64* @"__polly_perf_cycles_in_g_from__%next__to__%polly.merge_new_and_old"
+; CHECK-NEXT:  %16 = call i32 (...) @printf(i8* getelementptr inbounds ([20 x i8], [20 x i8]* @27, i32 0, i32 0), i8 addrspace(4)* getelementptr inbounds ([6 x i8], [6 x i8] addrspace(4)* @19, i32 0, i32 0), i8 addrspace(4)* getelementptr inbounds ([2 x i8], [2 x i8] addrspace(4)* @20, i32 0, i32 0), i8 addrspace(4)* getelementptr inbounds ([9 x i8], [9 x i8] addrspace(4)* @21, i32 0, i32 0), i8 addrspace(4)* getelementptr inbounds ([6 x i8], [6 x i8] addrspace(4)* @22, i32 0, i32 0), i8 addrspace(4)* getelementptr inbounds ([7 x i8], [7 x i8] addrspace(4)* @23, i32 0, i32 0), i8 addrspace(4)* getelementptr inbounds ([25 x i8], [25 x i8] addrspace(4)* @24, i32 0, i32 0), i8 addrspace(4)* getelementptr inbounds ([4 x i8], [4 x i8] addrspace(4)* @25, i32 0, i32 0), i64 %15, i8 addrspace(4)* getelementptr inbounds ([2 x i8], [2 x i8] addrspace(4)* @26, i32 0, i32 0))
+; CHECK-NEXT:  %17 = call i32 @fflush(i8* null)
+; CHECK-NEXT:  ret void