[lld] check cache in loadDylib before real_path (llvm#143595)

Author: rmaz

lld/MachO/DriverUtils.cpp

@@ -225,21 +225,44 @@ std::optional<StringRef> macho::resolveDylibPath(StringRef dylibPath) {
 // especially if it's a commonly re-exported core library.
 static DenseMap<CachedHashStringRef, DylibFile *> loadedDylibs;
 
+static StringRef realPathIfDifferent(StringRef path) {
+  SmallString<128> realPathBuf;
+  if (fs::real_path(path, realPathBuf))
+    return StringRef();
+
+  SmallString<128> absPathBuf = path;
+  if (!fs::make_absolute(absPathBuf) && realPathBuf == absPathBuf)
+    return StringRef();
+
+  return uniqueSaver().save(StringRef(realPathBuf));
+}
+
 DylibFile *macho::loadDylib(MemoryBufferRef mbref, DylibFile *umbrella,
                             bool isBundleLoader, bool explicitlyLinked) {
-  // Frameworks can be found from different symlink paths, so resolve
-  // symlinks before looking up in the dylib cache.
-  SmallString<128> realPath;
-  std::error_code err = fs::real_path(mbref.getBufferIdentifier(), realPath);
-  CachedHashStringRef path(!err ? uniqueSaver().save(StringRef(realPath))
-                                : mbref.getBufferIdentifier());
+  CachedHashStringRef path(mbref.getBufferIdentifier());
   DylibFile *&file = loadedDylibs[path];
   if (file) {
     if (explicitlyLinked)
       file->setExplicitlyLinked();
     return file;
   }
 
+  // Frameworks can be found from different symlink paths, so resolve
+  // symlinks and look up in the dylib cache.
+  CachedHashStringRef realPath(
+      realPathIfDifferent(mbref.getBufferIdentifier()));
+  if (!realPath.val().empty()) {
+    // Avoid map insertions here so that we do not invalidate the "file"
+    // reference.
+    auto it = loadedDylibs.find(realPath);
+    if (it != loadedDylibs.end()) {
+      DylibFile *realfile = it->second;
+      if (explicitlyLinked)
+        realfile->setExplicitlyLinked();
+      return realfile;
+    }
+  }
+
   DylibFile *newFile;
   file_magic magic = identify_magic(mbref.getBuffer());
   if (magic == file_magic::tapi_file) {
@@ -292,6 +315,11 @@ DylibFile *macho::loadDylib(MemoryBufferRef mbref, DylibFile *umbrella,
             sys::path::filename(newFile->installName) + "' because " +
             config->clientName + " is not an allowed client");
   }
+
+  // If the load path was a symlink, cache the real path too.
+  if (!realPath.val().empty())
+    loadedDylibs[realPath] = newFile;
+
   return newFile;
 }
 

lld/test/MachO/reexport-with-symlink.s

@@ -0,0 +1,74 @@
+# REQUIRES: aarch64, shell
+# RUN: rm -rf %t; split-file %s %t
+# RUN: ln -s Versions/A/Developer %t/Developer/Library/Frameworks/Developer.framework/
+# RUN: llvm-mc -filetype obj -triple arm64-apple-macos11.0 %t/test.s -o %t/test.o
+# RUN: %lld -arch arm64 -platform_version macos 11.0 11.0 -o %t/test -framework Developer -F %t/Developer/Library/Frameworks -L %t/Developer/usr/lib %t/test.o -t | FileCheck %s
+
+# CHECK: {{.*}}/Developer/Library/Frameworks/Developer.framework/Developer
+# CHECK: {{.*}}/Developer/usr/lib/libDeveloperSupport.tbd(@rpath/libDeveloperSupport.dylib)
+# CHECK-NOT: {{.*}}/Developer/Library/Frameworks/Developer.framework/Versions/A/Developer
+
+#--- Developer/Library/Frameworks/Developer.framework/Versions/A/Developer
+{
+  "tapi_tbd_version": 5,
+  "main_library": {
+    "target_info": [
+      {
+        "target": "arm64-macos"
+      }
+    ],
+    "install_names": [
+      {
+        "name": "@rpath/Developer.framework/Developer"
+      }
+    ],
+    "exported_symbols": [
+      {
+        "text": {
+          "global": ["_funcPublic"]
+        }
+      }
+    ]
+  }
+}
+#--- Developer/usr/lib/libDeveloperSupport.tbd
+{
+  "tapi_tbd_version": 5,
+  "main_library": {
+    "target_info": [
+      {
+        "target": "arm64-macos"
+      }
+    ],
+    "install_names": [
+      {
+        "name": "@rpath/libDeveloperSupport.dylib"
+      }
+    ],
+    "reexported_libraries": [
+      {
+        "names": [
+          "@rpath/Developer.framework/Versions/A/Developer"
+        ]
+      }
+    ],
+    "exported_symbols": [
+      {
+        "text": {
+          "global": ["_funcSupport"]
+        }
+      }
+    ]
+  }
+}
+#--- test.s
+.text
+.globl _main
+.linker_option "-lDeveloperSupport"
+
+_main:
+  ret
+
+.data
+  .quad _funcPublic
+  .quad _funcSupport