[Core] Add flag to check if RoundTripPasses need to be run.

This would allow other flavor specific contexts to override the default value,
if they want to optionally run the round trip passes.

There is some information lost like the original file owner of the atom with
RoundTripPasses. The Gnu flavor needs this information inorder to implement
LinkerScript matching and for other diagnostic outputs such as Map files.

The flag also can be used to record information in the Atom if the information
to the Writer needs to be conveyed through References too.

llvm-svn: 222983

3 files changed, 32 insertions, 4 deletions

diff --git a/lld/include/lld/Core/LinkingContext.h b/lld/include/lld/Core/LinkingContext.h
index b519373bd53..b8699106f71 100644
--- a/lld/include/lld/Core/LinkingContext.h
+++ b/lld/include/lld/Core/LinkingContext.h
@@ -318,8 +318,15 @@ public:
   /// Return the next ordinal and Increment it.
   virtual uint64_t getNextOrdinalAndIncrement() const { return _nextOrdinal++; }
 
-  /// @}
+#ifndef NDEBUG
+  void setRunRoundTripPass(bool roundTripPass) {
+    _runRoundTripPasses = roundTripPass;
+  }
+
+  bool runRoundTripPass() const { return _runRoundTripPasses; }
+#endif
 
+  /// @}
 protected:
   LinkingContext(); // Must be subclassed
 
@@ -350,6 +357,9 @@ protected:
   bool _allowRemainingUndefines;
   bool _logInputFiles;
   bool _allowShlibUndefines;
+#ifndef NDEBUG
+  bool _runRoundTripPasses;
+#endif
   OutputFileType _outputFileType;
   std::vector<StringRef> _deadStripRoots;
   std::map<std::string, std::string> _aliasSymbols;
diff --git a/lld/lib/Core/LinkingContext.cpp b/lld/lib/Core/LinkingContext.cpp
index 47942d66efe..ee738660e68 100644
--- a/lld/lib/Core/LinkingContext.cpp
+++ b/lld/lib/Core/LinkingContext.cpp
@@ -13,9 +13,28 @@
 #include "lld/Core/Simple.h"
 #include "lld/ReaderWriter/Writer.h"
 #include "llvm/ADT/Triple.h"
+#include "llvm/Support/Process.h"
 
 namespace lld {
 
+#ifndef NDEBUG
+LinkingContext::LinkingContext()
+    : _deadStrip(false), _allowDuplicates(false),
+      _globalsAreDeadStripRoots(false),
+      _searchArchivesToOverrideTentativeDefinitions(false),
+      _searchSharedLibrariesToOverrideTentativeDefinitions(false),
+      _warnIfCoalesableAtomsHaveDifferentCanBeNull(false),
+      _warnIfCoalesableAtomsHaveDifferentLoadName(false),
+      _printRemainingUndefines(true), _allowRemainingUndefines(false),
+      _logInputFiles(false), _allowShlibUndefines(false),
+      _runRoundTripPasses(false), _outputFileType(OutputFileType::Default),
+      _nextOrdinal(0) {
+  llvm::Optional<std::string> env =
+      llvm::sys::Process::GetEnv("LLD_RUN_ROUNDTRIP_TEST");
+  if (env.hasValue() && !env.getValue().empty())
+    setRunRoundTripPass(true);
+}
+#else
 LinkingContext::LinkingContext()
     : _deadStrip(false), _allowDuplicates(false),
       _globalsAreDeadStripRoots(false),
@@ -26,6 +45,7 @@ LinkingContext::LinkingContext()
       _printRemainingUndefines(true), _allowRemainingUndefines(false),
       _logInputFiles(false), _allowShlibUndefines(false),
       _outputFileType(OutputFileType::Default), _nextOrdinal(0) {}
+#endif
 
 LinkingContext::~LinkingContext() {}
 
diff --git a/lld/lib/Driver/Driver.cpp b/lld/lib/Driver/Driver.cpp
index 1095051c8bd..148d1003218 100644
--- a/lld/lib/Driver/Driver.cpp
+++ b/lld/lib/Driver/Driver.cpp
@@ -23,7 +23,6 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
-#include "llvm/Support/Process.h"
 #include "llvm/Support/raw_ostream.h"
 #include <mutex>
 
@@ -114,8 +113,7 @@ bool Driver::link(LinkingContext &context, raw_ostream &diagnostics) {
   context.addPasses(pm);
 
 #ifndef NDEBUG
-  llvm::Optional<std::string> env = llvm::sys::Process::GetEnv("LLD_RUN_ROUNDTRIP_TEST");
-  if (env.hasValue() && !env.getValue().empty()) {
+  if (context.runRoundTripPass()) {
     pm.add(std::unique_ptr<Pass>(new RoundTripYAMLPass(context)));
     pm.add(std::unique_ptr<Pass>(new RoundTripNativePass(context)));
   }