From: Guillaume Chatelet <gchatelet@google.com>
Date: Fri, 5 Apr 2019 15:18:59 +0000 (+0000)
Subject: Add an option do not dump the generated object on disk
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=99e08856aef1012c1b1662f5527d6c74bbbf7720;p=llvm

Add an option do not dump the generated object on disk

Reviewers: courbet

Subscribers: llvm-commits, bdb

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D60317

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@357769 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/docs/CommandGuide/llvm-exegesis.rst b/docs/CommandGuide/llvm-exegesis.rst
index 29f2cec2688..cbb900914cf 100644
--- a/docs/CommandGuide/llvm-exegesis.rst
+++ b/docs/CommandGuide/llvm-exegesis.rst
@@ -247,10 +247,16 @@ OPTIONS
 
  If set, ignore instructions that do not have a sched class (class idx = 0).
 
- .. option:: -mcpu=<cpu name>
+.. option:: -mcpu=<cpu name>
 
-  If set, measure the cpu characteristics using the counters for this CPU. This
-  is useful when creating new sched models (the host CPU is unknown to LLVM).
+ If set, measure the cpu characteristics using the counters for this CPU. This
+ is useful when creating new sched models (the host CPU is unknown to LLVM).
+
+.. option:: --dump-object-to-disk=true
+
+ By default, llvm-exegesis will dump the generated code to a temporary file to
+ enable code inspection. You may disable it to speed up the execution and save
+ disk space.
 
 EXIT STATUS
 -----------
diff --git a/tools/llvm-exegesis/lib/BenchmarkRunner.cpp b/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
index 32b68a5c23d..18ce4ccad28 100644
--- a/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
+++ b/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
@@ -66,8 +66,9 @@ private:
       CounterName = CounterName.trim();
       pfm::PerfEvent PerfEvent(CounterName);
       if (!PerfEvent.valid())
-        llvm::report_fatal_error(
-            llvm::Twine("invalid perf event '").concat(CounterName).concat("'"));
+        llvm::report_fatal_error(llvm::Twine("invalid perf event '")
+                                     .concat(CounterName)
+                                     .concat("'"));
       pfm::Counter Counter(PerfEvent);
       Scratch->clear();
       {
@@ -96,7 +97,8 @@ private:
 
 InstructionBenchmark
 BenchmarkRunner::runConfiguration(const BenchmarkCode &BC,
-                                  unsigned NumRepetitions) const {
+                                  unsigned NumRepetitions,
+                                  bool DumpObjectToDisk) const {
   InstructionBenchmark InstrBenchmark;
   InstrBenchmark.Mode = Mode;
   InstrBenchmark.CpuName = State.getTargetMachine().getTargetCPU();
@@ -129,15 +131,27 @@ BenchmarkRunner::runConfiguration(const BenchmarkCode &BC,
 
   // Assemble NumRepetitions instructions repetitions of the snippet for
   // measurements.
-  auto ObjectFilePath = writeObjectFile(
-      BC, GenerateInstructions(BC, InstrBenchmark.NumRepetitions));
-  if (llvm::Error E = ObjectFilePath.takeError()) {
-    InstrBenchmark.Error = llvm::toString(std::move(E));
-    return InstrBenchmark;
+  const auto Code = GenerateInstructions(BC, InstrBenchmark.NumRepetitions);
+
+  llvm::object::OwningBinary<llvm::object::ObjectFile> ObjectFile;
+  if (DumpObjectToDisk) {
+    auto ObjectFilePath = writeObjectFile(BC, Code);
+    if (llvm::Error E = ObjectFilePath.takeError()) {
+      InstrBenchmark.Error = llvm::toString(std::move(E));
+      return InstrBenchmark;
+    }
+    llvm::outs() << "Check generated assembly with: /usr/bin/objdump -d "
+                 << *ObjectFilePath << "\n";
+    ObjectFile = getObjectFromFile(*ObjectFilePath);
+  } else {
+    llvm::SmallString<0> Buffer;
+    llvm::raw_svector_ostream OS(Buffer);
+    assembleToStream(State.getExegesisTarget(), State.createTargetMachine(),
+                     BC.LiveIns, BC.RegisterInitialValues, Code, OS);
+    ObjectFile = getObjectFromBuffer(OS.str());
   }
-  llvm::outs() << "Check generated assembly with: /usr/bin/objdump -d "
-               << *ObjectFilePath << "\n";
-  const FunctionExecutorImpl Executor(State, getObjectFromFile(*ObjectFilePath),
+
+  const FunctionExecutorImpl Executor(State, std::move(ObjectFile),
                                       Scratch.get());
   auto Measurements = runMeasurements(Executor);
   if (llvm::Error E = Measurements.takeError()) {
diff --git a/tools/llvm-exegesis/lib/BenchmarkRunner.h b/tools/llvm-exegesis/lib/BenchmarkRunner.h
index 4387bc8456e..395c0f8e32d 100644
--- a/tools/llvm-exegesis/lib/BenchmarkRunner.h
+++ b/tools/llvm-exegesis/lib/BenchmarkRunner.h
@@ -45,7 +45,8 @@ public:
   virtual ~BenchmarkRunner();
 
   InstructionBenchmark runConfiguration(const BenchmarkCode &Configuration,
-                                        unsigned NumRepetitions) const;
+                                        unsigned NumRepetitions,
+                                        bool DumpObjectToDisk) const;
 
   // Scratch space to run instructions that touch memory.
   struct ScratchSpace {
@@ -85,7 +86,6 @@ private:
   writeObjectFile(const BenchmarkCode &Configuration,
                   llvm::ArrayRef<llvm::MCInst> Code) const;
 
-
   const std::unique_ptr<ScratchSpace> Scratch;
 };
 
diff --git a/tools/llvm-exegesis/llvm-exegesis.cpp b/tools/llvm-exegesis/llvm-exegesis.cpp
index fb2f2ff0eef..7339baf8f8e 100644
--- a/tools/llvm-exegesis/llvm-exegesis.cpp
+++ b/tools/llvm-exegesis/llvm-exegesis.cpp
@@ -137,6 +137,12 @@ static cl::opt<std::string> CpuName(
     cl::desc("cpu name to use for pfm counters, leave empty to autodetect"),
     cl::cat(Options), cl::init(""));
 
+static cl::opt<bool>
+    DumpObjectToDisk("dump-object-to-disk",
+                     cl::desc("dumps the generated benchmark object to disk "
+                              "and prints a message to access it"),
+                     cl::cat(BenchmarkOptions), cl::init(true));
+
 static ExitOnError ExitOnErr;
 
 #ifdef LLVM_EXEGESIS_INITIALIZE_NATIVE_TARGET
@@ -406,7 +412,7 @@ void benchmarkMain() {
 
   for (const BenchmarkCode &Conf : Configurations) {
     InstructionBenchmark Result =
-        Runner->runConfiguration(Conf, NumRepetitions);
+        Runner->runConfiguration(Conf, NumRepetitions, DumpObjectToDisk);
     ExitOnErr(Result.writeYaml(State, BenchmarkFile));
   }
   exegesis::pfm::pfmTerminate();