[llvm-exegesis][NFC] Split BenchmarkRunner class

Summary:
The snippet-generation part goes to the SnippetGenerator class.

This will allow benchmarking arbitrary code (see PR38437).

Reviewers: gchatelet

Subscribers: mgorny, tschuett, llvm-commits

Differential Revision: https://reviews.llvm.org/D51979

llvm-svn: 342117

1 files changed, 74 insertions, 0 deletions

diff --git a/llvm/tools/llvm-exegesis/lib/SnippetGenerator.h b/llvm/tools/llvm-exegesis/lib/SnippetGenerator.h
new file mode 100644
index 00000000000..ced8ebc5a28
--- /dev/null
+++ b/llvm/tools/llvm-exegesis/lib/SnippetGenerator.h
@@ -0,0 +1,74 @@
+//===-- SnippetGenerator.h --------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Defines the abstract SnippetGenerator class for generating code that allows
+/// measuring a certain property of instructions (e.g. latency).
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TOOLS_LLVM_EXEGESIS_SNIPPETGENERATOR_H
+#define LLVM_TOOLS_LLVM_EXEGESIS_SNIPPETGENERATOR_H
+
+#include "Assembler.h"
+#include "BenchmarkCode.h"
+#include "LlvmState.h"
+#include "MCInstrDescView.h"
+#include "RegisterAliasing.h"
+#include "llvm/MC/MCInst.h"
+#include "llvm/Support/Error.h"
+#include <cstdlib>
+#include <memory>
+#include <vector>
+
+namespace exegesis {
+
+// A class representing failures that happened during Benchmark, they are used
+// to report informations to the user.
+class SnippetGeneratorFailure : public llvm::StringError {
+public:
+  SnippetGeneratorFailure(const llvm::Twine &S);
+};
+
+// Common code for all benchmark modes.
+class SnippetGenerator {
+public:
+  explicit SnippetGenerator(const LLVMState &State);
+
+  virtual ~SnippetGenerator();
+
+  // Calls generateCodeTemplate and expands it into one or more BenchmarkCode.
+  llvm::Expected<std::vector<BenchmarkCode>>
+  generateConfigurations(unsigned Opcode) const;
+
+  // Given a snippet, computes which registers the setup code needs to define.
+  std::vector<unsigned>
+  computeRegsToDef(const std::vector<InstructionBuilder> &Snippet) const;
+
+protected:
+  const LLVMState &State;
+  const RegisterAliasingTrackerCache RATC;
+
+  // Generates a single code template that has a self-dependency.
+  llvm::Expected<CodeTemplate>
+  generateSelfAliasingCodeTemplate(const Instruction &Instr) const;
+  // Generates a single code template without assignment constraints.
+  llvm::Expected<CodeTemplate>
+  generateUnconstrainedCodeTemplate(const Instruction &Instr,
+                                    llvm::StringRef Msg) const;
+
+private:
+  // API to be implemented by subclasses.
+  virtual llvm::Expected<CodeTemplate>
+  generateCodeTemplate(unsigned Opcode) const = 0;
+};
+
+} // namespace exegesis
+
+#endif // LLVM_TOOLS_LLVM_EXEGESIS_SNIPPETGENERATOR_H