[PATCH] D115775: [lld-macho] Handle $ld$hide[$os] symbols.

[Vy Nguyen via Phabricator via llvm-commits]

oontvoo created this revision.
Herald added a project: lld-macho.
Herald added a reviewer: lld-macho.
oontvoo requested review of this revision.
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PR/52708


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D115775

Files:
  lld/MachO/InputFiles.cpp
  lld/MachO/InputFiles.h


Index: lld/MachO/InputFiles.h
===================================================================
--- lld/MachO/InputFiles.h
+++ lld/MachO/InputFiles.h
@@ -190,7 +190,10 @@
   bool handleLDSymbol(StringRef originalName);
   void handleLDPreviousSymbol(StringRef name, StringRef originalName);
   void handleLDInstallNameSymbol(StringRef name, StringRef originalName);
+  void handleHideSymbol(StringRef name, StringRef originalName);
   void checkAppExtensionSafety(bool dylibIsAppExtensionSafe) const;
+
+  llvm::DenseSet<llvm::CachedStringRef> hiddenSymbols;
 };
 
 // .a file
Index: lld/MachO/InputFiles.cpp
===================================================================
--- lld/MachO/InputFiles.cpp
+++ lld/MachO/InputFiles.cpp
@@ -1154,6 +1154,8 @@
                   return;
                 bool isWeakDef = flags & EXPORT_SYMBOL_FLAGS_WEAK_DEFINITION;
                 bool isTlv = flags & EXPORT_SYMBOL_FLAGS_KIND_THREAD_LOCAL;
+                if (hiddenSymbols.contains(cachedHashStringRef(savedName)))
+                  return;
                 symbols.push_back(symtab->addDylib(savedName, exportingFile,
                                                    isWeakDef, isTlv));
               });
@@ -1289,6 +1291,8 @@
     handleLDPreviousSymbol(name, originalName);
   else if (action == "install_name")
     handleLDInstallNameSymbol(name, originalName);
+  else if (action == "hide")
+    handleHideSymbol(name, originalName);
   return true;
 }
 
@@ -1357,6 +1361,28 @@
     this->installName = saver.save(installName);
 }
 
+void DylibFile::handleHideSymbol(StringRef name, StringRef originalName) {
+  StringRef symbolName;
+  bool shouldHide = true;
+  if (name.startswith("os")) {
+    // If it's hidden based on versions.
+    StringRef minVersion;
+    std::tie(minVersion, symbolName) = name.split('$');
+    VersionTuple versionTup;
+    if (versionTup.tryParse(minVersion)) {
+      warn("Failed to parse hidden version, symbol `" + originalName +
+           "` ignored.");
+      return;
+    }
+    shouldHide = versionTup == config->platformInfo.minimum;
+  } else
+    symbolName = name;
+
+  if (!shouldHide)
+    return;
+  hiddenSymbol.insert(CachedHashStringRef(symbolName));
+}
+
 void DylibFile::checkAppExtensionSafety(bool dylibIsAppExtensionSafe) const {
   if (config->applicationExtension && !dylibIsAppExtensionSafe)
     warn("using '-application_extension' with unsafe dylib: " + toString(this));


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