[llvm-exegesis] Add options to SnippetGenerator.

Summary:
This adds a `-max-configs-per-opcode` option to limit the number of
configs per opcode.

Reviewers: gchatelet

Subscribers: tschuett, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D68642

llvm-svn: 374054

8 files changed, 46 insertions, 25 deletions

diff --git a/llvm/tools/llvm-exegesis/lib/Latency.h b/llvm/tools/llvm-exegesis/lib/Latency.h
index 503f91daf89..0ad0c2cea9b 100644
--- a/llvm/tools/llvm-exegesis/lib/Latency.h
+++ b/llvm/tools/llvm-exegesis/lib/Latency.h
@@ -24,7 +24,7 @@ namespace exegesis {
 
 class LatencySnippetGenerator : public SnippetGenerator {
 public:
-  LatencySnippetGenerator(const LLVMState &State) : SnippetGenerator(State) {}
+  using SnippetGenerator::SnippetGenerator;
   ~LatencySnippetGenerator() override;
 
   llvm::Expected<std::vector<CodeTemplate>>
diff --git a/llvm/tools/llvm-exegesis/lib/SnippetGenerator.cpp b/llvm/tools/llvm-exegesis/lib/SnippetGenerator.cpp
index 879962001e6..1b16259b8e6 100644
--- a/llvm/tools/llvm-exegesis/lib/SnippetGenerator.cpp
+++ b/llvm/tools/llvm-exegesis/lib/SnippetGenerator.cpp
@@ -33,7 +33,8 @@ std::vector<CodeTemplate> getSingleton(CodeTemplate &&CT) {
 SnippetGeneratorFailure::SnippetGeneratorFailure(const llvm::Twine &S)
     : llvm::StringError(S, llvm::inconvertibleErrorCode()) {}
 
-SnippetGenerator::SnippetGenerator(const LLVMState &State) : State(State) {}
+SnippetGenerator::SnippetGenerator(const LLVMState &State, const Options &Opts)
+    : State(State), Opts(Opts) {}
 
 SnippetGenerator::~SnippetGenerator() = default;
 
@@ -81,6 +82,9 @@ SnippetGenerator::generateConfigurations(
             computeRegisterInitialValues(CT.Instructions);
         BC.Key.Config = CT.Config;
         Output.push_back(std::move(BC));
+        if (Output.size() >= Opts.MaxConfigsPerOpcode)
+          return Output; // Early exit if we exceeded the number of allowed
+                         // configs.
       }
     }
     return Output;
diff --git a/llvm/tools/llvm-exegesis/lib/SnippetGenerator.h b/llvm/tools/llvm-exegesis/lib/SnippetGenerator.h
index c2ea1c12473..8e8cd6fcb99 100644
--- a/llvm/tools/llvm-exegesis/lib/SnippetGenerator.h
+++ b/llvm/tools/llvm-exegesis/lib/SnippetGenerator.h
@@ -51,7 +51,11 @@ public:
 // Common code for all benchmark modes.
 class SnippetGenerator {
 public:
-  explicit SnippetGenerator(const LLVMState &State);
+  struct Options {
+    unsigned MaxConfigsPerOpcode = 1;
+  };
+
+  explicit SnippetGenerator(const LLVMState &State, const Options &Opts);
 
   virtual ~SnippetGenerator();
 
@@ -66,6 +70,7 @@ public:
 
 protected:
   const LLVMState &State;
+  const Options Opts;
 
 private:
   // API to be implemented by subclasses.
diff --git a/llvm/tools/llvm-exegesis/lib/Target.cpp b/llvm/tools/llvm-exegesis/lib/Target.cpp
index a5ba24c20f2..7e27627c98c 100644
--- a/llvm/tools/llvm-exegesis/lib/Target.cpp
+++ b/llvm/tools/llvm-exegesis/lib/Target.cpp
@@ -36,17 +36,17 @@ void ExegesisTarget::registerTarget(ExegesisTarget *Target) {
   FirstTarget = Target;
 }
 
-std::unique_ptr<SnippetGenerator>
-ExegesisTarget::createSnippetGenerator(InstructionBenchmark::ModeE Mode,
-                                       const LLVMState &State) const {
+std::unique_ptr<SnippetGenerator> ExegesisTarget::createSnippetGenerator(
+    InstructionBenchmark::ModeE Mode, const LLVMState &State,
+    const SnippetGenerator::Options &Opts) const {
   switch (Mode) {
   case InstructionBenchmark::Unknown:
     return nullptr;
   case InstructionBenchmark::Latency:
-    return createLatencySnippetGenerator(State);
+    return createLatencySnippetGenerator(State, Opts);
   case InstructionBenchmark::Uops:
   case InstructionBenchmark::InverseThroughput:
-    return createUopsSnippetGenerator(State);
+    return createUopsSnippetGenerator(State, Opts);
   }
   return nullptr;
 }
@@ -66,14 +66,14 @@ ExegesisTarget::createBenchmarkRunner(InstructionBenchmark::ModeE Mode,
   return nullptr;
 }
 
-std::unique_ptr<SnippetGenerator>
-ExegesisTarget::createLatencySnippetGenerator(const LLVMState &State) const {
-  return std::make_unique<LatencySnippetGenerator>(State);
+std::unique_ptr<SnippetGenerator> ExegesisTarget::createLatencySnippetGenerator(
+    const LLVMState &State, const SnippetGenerator::Options &Opts) const {
+  return std::make_unique<LatencySnippetGenerator>(State, Opts);
 }
 
-std::unique_ptr<SnippetGenerator>
-ExegesisTarget::createUopsSnippetGenerator(const LLVMState &State) const {
-  return std::make_unique<UopsSnippetGenerator>(State);
+std::unique_ptr<SnippetGenerator> ExegesisTarget::createUopsSnippetGenerator(
+    const LLVMState &State, const SnippetGenerator::Options &Opts) const {
+  return std::make_unique<UopsSnippetGenerator>(State, Opts);
 }
 
 std::unique_ptr<BenchmarkRunner> ExegesisTarget::createLatencyBenchmarkRunner(
diff --git a/llvm/tools/llvm-exegesis/lib/Target.h b/llvm/tools/llvm-exegesis/lib/Target.h
index 70313a7a2f7..511104d5947 100644
--- a/llvm/tools/llvm-exegesis/lib/Target.h
+++ b/llvm/tools/llvm-exegesis/lib/Target.h
@@ -125,7 +125,8 @@ public:
   // Creates a snippet generator for the given mode.
   std::unique_ptr<SnippetGenerator>
   createSnippetGenerator(InstructionBenchmark::ModeE Mode,
-                         const LLVMState &State) const;
+                         const LLVMState &State,
+                         const SnippetGenerator::Options &Opts) const;
   // Creates a benchmark runner for the given mode.
   std::unique_ptr<BenchmarkRunner>
   createBenchmarkRunner(InstructionBenchmark::ModeE Mode,
@@ -151,9 +152,9 @@ private:
   // Targets can implement their own snippet generators/benchmarks runners by
   // implementing these.
   std::unique_ptr<SnippetGenerator> virtual createLatencySnippetGenerator(
-      const LLVMState &State) const;
+      const LLVMState &State, const SnippetGenerator::Options &Opts) const;
   std::unique_ptr<SnippetGenerator> virtual createUopsSnippetGenerator(
-      const LLVMState &State) const;
+      const LLVMState &State, const SnippetGenerator::Options &Opts) const;
   std::unique_ptr<BenchmarkRunner> virtual createLatencyBenchmarkRunner(
       const LLVMState &State, InstructionBenchmark::ModeE Mode) const;
   std::unique_ptr<BenchmarkRunner> virtual createUopsBenchmarkRunner(
diff --git a/llvm/tools/llvm-exegesis/lib/Uops.h b/llvm/tools/llvm-exegesis/lib/Uops.h
index 23caff26658..fcfeabe99ee 100644
--- a/llvm/tools/llvm-exegesis/lib/Uops.h
+++ b/llvm/tools/llvm-exegesis/lib/Uops.h
@@ -22,7 +22,7 @@ namespace exegesis {
 
 class UopsSnippetGenerator : public SnippetGenerator {
 public:
-  UopsSnippetGenerator(const LLVMState &State) : SnippetGenerator(State) {}
+  using SnippetGenerator::SnippetGenerator;
   ~UopsSnippetGenerator() override;
 
   llvm::Expected<std::vector<CodeTemplate>>
diff --git a/llvm/tools/llvm-exegesis/lib/X86/Target.cpp b/llvm/tools/llvm-exegesis/lib/X86/Target.cpp
index ce66610891d..1532af8ddec 100644
--- a/llvm/tools/llvm-exegesis/lib/X86/Target.cpp
+++ b/llvm/tools/llvm-exegesis/lib/X86/Target.cpp
@@ -462,14 +462,16 @@ private:
                             sizeof(kUnavailableRegisters[0]));
   }
 
-  std::unique_ptr<SnippetGenerator>
-  createLatencySnippetGenerator(const LLVMState &State) const override {
-    return std::make_unique<X86LatencySnippetGenerator>(State);
+  std::unique_ptr<SnippetGenerator> createLatencySnippetGenerator(
+      const LLVMState &State,
+      const SnippetGenerator::Options &Opts) const override {
+    return std::make_unique<X86LatencySnippetGenerator>(State, Opts);
   }
 
-  std::unique_ptr<SnippetGenerator>
-  createUopsSnippetGenerator(const LLVMState &State) const override {
-    return std::make_unique<X86UopsSnippetGenerator>(State);
+  std::unique_ptr<SnippetGenerator> createUopsSnippetGenerator(
+      const LLVMState &State,
+      const SnippetGenerator::Options &Opts) const override {
+    return std::make_unique<X86UopsSnippetGenerator>(State, Opts);
   }
 
   bool matchesArch(llvm::Triple::ArchType Arch) const override {
diff --git a/llvm/tools/llvm-exegesis/llvm-exegesis.cpp b/llvm/tools/llvm-exegesis/llvm-exegesis.cpp
index 616b7c96232..e86dc817cb2 100644
--- a/llvm/tools/llvm-exegesis/llvm-exegesis.cpp
+++ b/llvm/tools/llvm-exegesis/llvm-exegesis.cpp
@@ -95,6 +95,12 @@ static cl::opt<unsigned>
                    cl::desc("number of time to repeat the asm snippet"),
                    cl::cat(BenchmarkOptions), cl::init(10000));
 
+static cl::opt<unsigned> MaxConfigsPerOpcode(
+    "max-configs-per-opcode",
+    cl::desc(
+        "allow to snippet generator to generate at most that many configs"),
+    cl::cat(BenchmarkOptions), cl::init(1));
+
 static cl::opt<bool> IgnoreInvalidSchedClass(
     "ignore-invalid-sched-class",
     cl::desc("ignore instructions that do not define a sched class"),
@@ -214,8 +220,11 @@ generateSnippets(const LLVMState &State, unsigned Opcode,
   if (InstrDesc.isCall() || InstrDesc.isReturn())
     return make_error<Failure>("Unsupported opcode: isCall/isReturn");
 
+  SnippetGenerator::Options Options;
+  Options.MaxConfigsPerOpcode = MaxConfigsPerOpcode;
   const std::unique_ptr<SnippetGenerator> Generator =
-      State.getExegesisTarget().createSnippetGenerator(BenchmarkMode, State);
+      State.getExegesisTarget().createSnippetGenerator(BenchmarkMode, State,
+                                                       Options);
   if (!Generator)
     llvm::report_fatal_error("cannot create snippet generator");
   return Generator->generateConfigurations(Instr, ForbiddenRegs);