From 3dadbdfd5f87401c9f0a1b8679c279a8e0a9d8a7 Mon Sep 17 00:00:00 2001
From: Edwin Smith <smith@fb.com>
Date: Wed, 19 Oct 2016 08:17:33 -0700
Subject: [PATCH] Change type-scan opt-out from build switch to env variable.

Summary: Using an environment variable is more buck-cache friendly.

Reviewed By: markw65

Differential Revision: D4037819

fbshipit-source-id: bb9aacbd531523a8a6ae59c57e10ba88402d7fbb
---
 hphp/runtime/base/heap-collect.cpp              |  2 +-
 hphp/tools/type-info-gens/gen-type-scanners.cpp | 18 +++++++++++++-----
 hphp/util/type-scan.h                           |  8 --------
 3 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/hphp/runtime/base/heap-collect.cpp b/hphp/runtime/base/heap-collect.cpp
index da1e1d81e71..4836671e894 100644
--- a/hphp/runtime/base/heap-collect.cpp
+++ b/hphp/runtime/base/heap-collect.cpp
@@ -797,7 +797,7 @@ void logCollection(const char* phase, const Marker& mkr) {
   }
   auto sample = logCommon();
   sample.setStr("phase", phase);
-  std::string scanner(type_scan::kBuildScanners ? "typescan" : "ts-cons");
+  std::string scanner(type_scan::hasNonConservative() ? "typescan" : "ts-cons");
   sample.setStr("scanner", !debug ? scanner : scanner + "-debug");
   sample.setInt("gc_num", t_gc_num);
   // timers of gc-sub phases
diff --git a/hphp/tools/type-info-gens/gen-type-scanners.cpp b/hphp/tools/type-info-gens/gen-type-scanners.cpp
index 9e2abbe07ee..a00f5fff230 100644
--- a/hphp/tools/type-info-gens/gen-type-scanners.cpp
+++ b/hphp/tools/type-info-gens/gen-type-scanners.cpp
@@ -217,7 +217,7 @@ struct Generator {
  public:
   // Parse out all the debug information out of the specified file and do the
   // analysis generating the layouts.
-  explicit Generator(const std::string&);
+  explicit Generator(const std::string&, bool skip);
 
   // Turn the layouts into C++ code, writing to the specified ostream.
   void operator()(std::ostream&) const;
@@ -592,13 +592,13 @@ struct Generator::IndexedType {
   folly::Optional<LayoutError> errors;
 };
 
-Generator::Generator(const std::string& filename) {
+Generator::Generator(const std::string& filename, bool skip) {
   // Either this platform has no support for parsing debug information, or the
   // preprocessor symbol to enable actually building scanner isn't
   // enabled. Either way, just bail out. Everything will get a conservative
   // scanner by default if someone actually tries to use the scanners at
   // runtime.
-  if (!HPHP::type_scan::kBuildScanners) return;
+  if (skip) return;
 
   m_parser = TypeParser::make(filename);
 
@@ -3170,7 +3170,8 @@ int main(int argc, char** argv) {
      "filename to read debug-info from")
     ("output_file",
      po::value<std::string>()->required(),
-     "filename of generated scanners");
+     "filename of generated scanners")
+    ("skip", "do not scan dwarf, generate conservative scanners");
 
   try {
     po::variables_map vm;
@@ -3182,6 +3183,13 @@ int main(int argc, char** argv) {
       return 1;
     }
 
+#ifdef __clang__
+  /* Doesn't work with Clang at the moment. t10336705 */
+  auto skip = true;
+#else
+  auto skip = vm.count("skip") || getenv("HHVM_DISABLE_TYPE_SCANNERS");
+#endif
+
     po::notify(vm);
 
     const auto output_filename =
@@ -3196,7 +3204,7 @@ int main(int argc, char** argv) {
 
     try {
       const auto source_executable = vm["source_file"].as<std::string>();
-      Generator generator{source_executable};
+      Generator generator{source_executable, skip};
       std::ofstream output_file{output_filename};
       generator(output_file);
     } catch (const debug_parser::Exception& exn) {
diff --git a/hphp/util/type-scan.h b/hphp/util/type-scan.h
index 60ce45dadc9..2122b37f408 100644
--- a/hphp/util/type-scan.h
+++ b/hphp/util/type-scan.h
@@ -303,14 +303,6 @@ struct Scanner {
   std::vector<std::pair<const void*, std::size_t>> m_conservative;
 };
 
-constexpr bool kBuildScanners =
-  /* Doesn't work with Clang at the moment. t10336705 */
-#if !defined(HHVM_DISABLE_TYPE_SCANNERS) && !defined(__clang__)
-  true;
-#else
-  false;
-#endif
-
 /*
  * Type annotations to change generated function behavior:
  *
-- 
2.11.4.GIT