Dump instruction set features in .cfg

This commit adds a compilation block at the beginning of the .cfg
dumped by the optimizing compiler when --dump-cfg is enabled.

The compilation block appears in the following form:

begin_compilation
  name "isa_features:feature1,-feature2"
  method "isa_features:feature1,-feature2"
  date 1580721972
end_compilation

This compilation block dump is passed to checker script (see
https://android-review.googlesource.com/c/platform/art/+/1290997)
for checking if a certain instruction set feature was used at compile
time.

Author:    Fabio Rinaldi
Committer: Artem Serov

Bug: 147876827
Test: ./art/tools/checker/run_unit_tests.py
Test: test.py --target --optimizing
Change-Id: If4309af4bab892f715aad1d3bd338f8ee11e497c

1 files changed, 14 insertions, 0 deletions

diff --git a/compiler/optimizing/optimizing_compiler.cc b/compiler/optimizing/optimizing_compiler.cc
index bae402e596..de86c44246 100644
--- a/compiler/optimizing/optimizing_compiler.cc
+++ b/compiler/optimizing/optimizing_compiler.cc
@@ -400,6 +400,9 @@ class OptimizingCompiler final : public Compiler {
 
   std::vector<uint8_t> GenerateJitDebugInfo(const debug::MethodDebugInfo& method_debug_info);
 
+  // This must be called before any other function that dumps data to the cfg
+  void DumpInstructionSetFeaturesToCfg() const;
+
   std::unique_ptr<OptimizingCompilerStats> compilation_stats_;
 
   std::unique_ptr<std::ostream> visualizer_output_;
@@ -421,6 +424,7 @@ OptimizingCompiler::OptimizingCompiler(const CompilerOptions& compiler_options,
     std::ios_base::openmode cfg_file_mode =
         compiler_options.GetDumpCfgAppend() ? std::ofstream::app : std::ofstream::out;
     visualizer_output_.reset(new std::ofstream(cfg_file_name, cfg_file_mode));
+    DumpInstructionSetFeaturesToCfg();
   }
   if (compiler_options.GetDumpStats()) {
     compilation_stats_.reset(new OptimizingCompilerStats());
@@ -433,6 +437,16 @@ OptimizingCompiler::~OptimizingCompiler() {
   }
 }
 
+void OptimizingCompiler::DumpInstructionSetFeaturesToCfg() const {
+  const CompilerOptions& compiler_options = GetCompilerOptions();
+  const InstructionSetFeatures* features = compiler_options.GetInstructionSetFeatures();
+  std::string features_string = "isa_features:" + features->GetFeatureString();
+  // It is assumed that visualizer_output_ is empty when calling this function, hence the fake
+  // compilation block containing the ISA features will be printed at the beginning of the .cfg
+  // file.
+  *visualizer_output_ << HGraphVisualizer::InsertMetaDataAsCompilationBlock(features_string);
+}
+
 bool OptimizingCompiler::CanCompileMethod(uint32_t method_idx ATTRIBUTE_UNUSED,
                                           const DexFile& dex_file ATTRIBUTE_UNUSED) const {
   return true;