Strip the producers section in --strip-producers (#1875)

WebAssembly/tool-conventions#93 has a summary of emscripten's current thinking on this. For Binaryen, we don't want to do anything to the producers section by default, but do want it to be possible to optionally remove it. To achieve that, this PR

 * creates a --strip-producers pass that removes that section.
 * creates a --strip-debug pass that removes debug info, same as the old --strip, which is still around but deprecated.

A followup in emscripten will use this pass by default.

1 files changed, 24 insertions, 10 deletions

diff --git a/src/passes/Strip.cpp b/src/passes/Strip.cpp
index d2ebbe129..8ab712cb1 100644
--- a/src/passes/Strip.cpp
+++ b/src/passes/Strip.cpp
@@ -15,10 +15,12 @@
  */
 
 //
-// Similar to strip-ing a native binary, this removes debug info
-// and related things like source map URLs, names section, etc.
+// Similar to strip-ing a native binary, this family of passes can
+// removes debug info and other things.
 //
 
+#include <functional>
+
 #include "wasm.h"
 #include "wasm-binary.h"
 #include "pass.h"
@@ -28,6 +30,12 @@ using namespace std;
 namespace wasm {
 
 struct Strip : public Pass {
+  // A function that returns true if the method should be removed.
+  typedef std::function<bool (UserSection&)> Decider;
+  Decider decider;
+
+  Strip(Decider decider) : decider(decider) {}
+
   void run(PassRunner* runner, Module* module) override {
     // Remove name and debug sections.
     auto& sections = module->userSections;
@@ -35,12 +43,7 @@ struct Strip : public Pass {
       std::remove_if(
         sections.begin(),
         sections.end(),
-        [&](const UserSection& curr) {
-          return curr.name == BinaryConsts::UserSections::Name ||
-                 curr.name == BinaryConsts::UserSections::SourceMapUrl ||
-                 curr.name.find(".debug") == 0 ||
-                 curr.name.find("reloc..debug") == 0;
-        }
+        decider
       ),
       sections.end()
     );
@@ -53,8 +56,19 @@ struct Strip : public Pass {
   }
 };
 
-Pass *createStripPass() {
-  return new Strip();
+Pass *createStripDebugPass() {
+  return new Strip([&](const UserSection& curr) {
+    return curr.name == BinaryConsts::UserSections::Name ||
+           curr.name == BinaryConsts::UserSections::SourceMapUrl ||
+           curr.name.find(".debug") == 0 ||
+           curr.name.find("reloc..debug") == 0;
+  });
+}
+
+Pass *createStripProducersPass() {
+  return new Strip([&](const UserSection& curr) {
+    return curr.name == BinaryConsts::UserSections::Producers;
+  });
 }
 
 } // namespace wasm