[Autolink Extract] Filter out common Swift libraries from being linked more than once

A partial solution to #58380

Author: artemcm

lib/DriverTool/autolink_extract_main.cpp

@@ -113,6 +113,7 @@ class AutolinkExtractInvocation {
 static bool
 extractLinkerFlagsFromObjectFile(const llvm::object::ObjectFile *ObjectFile,
                                  std::vector<std::string> &LinkerFlags,
+                                 std::unordered_map<std::string, bool> &CommonAddedSwiftLibraries,
                                  CompilerInstance &Instance) {
   // Search for the section we hold autolink entries in
   for (auto &Section : ObjectFile->sections()) {
@@ -140,8 +141,18 @@ extractLinkerFlagsFromObjectFile(const llvm::object::ObjectFile *ObjectFile,
       llvm::SmallVector<llvm::StringRef, 4> SplitFlags;
       SectionData->split(SplitFlags, llvm::StringRef("\0", 1), -1,
                          /*KeepEmpty=*/false);
-      for (const auto &Flag : SplitFlags)
-        LinkerFlags.push_back(Flag.str());
+      for (const auto &Flag : SplitFlags) {
+        // If it is one of the common Swift library flags,
+        // only add if not seen before.
+        if (auto It = CommonAddedSwiftLibraries.find(Flag.str());
+            It != CommonAddedSwiftLibraries.end()) {
+          if (It->second == false) {
+            LinkerFlags.push_back(Flag.str());
+            It->second = true;
+          }
+        } else
+          LinkerFlags.push_back(Flag.str());
+      }
     }
   }
   return false;
@@ -153,6 +164,7 @@ extractLinkerFlagsFromObjectFile(const llvm::object::ObjectFile *ObjectFile,
 static bool
 extractLinkerFlagsFromObjectFile(const llvm::object::WasmObjectFile *ObjectFile,
                                  std::vector<std::string> &LinkerFlags,
+                                 std::unordered_map<std::string, bool> &CommonAddedSwiftLibraries,
                                  CompilerInstance &Instance) {
   // Search for the data segment we hold autolink entries in
   for (const llvm::object::WasmSegment &Segment : ObjectFile->dataSegments()) {
@@ -164,8 +176,18 @@ extractLinkerFlagsFromObjectFile(const llvm::object::WasmObjectFile *ObjectFile,
       llvm::SmallVector<llvm::StringRef, 4> SplitFlags;
       SegmentData.split(SplitFlags, llvm::StringRef("\0", 1), -1,
                         /*KeepEmpty=*/false);
-      for (const auto &Flag : SplitFlags)
-        LinkerFlags.push_back(Flag.str());
+      for (const auto &Flag : SplitFlags) {
+        // If it is one of the common Swift library flags,
+        // only add if not seen before.
+        if (auto It = CommonAddedSwiftLibraries.find(Flag.str());
+            It != CommonAddedSwiftLibraries.end()) {
+          if (It->second == false) {
+            LinkerFlags.push_back(Flag.str());
+            It->second = true;
+          }
+        } else
+          LinkerFlags.push_back(Flag.str());
+      }
     }
   }
   return false;
@@ -178,12 +200,13 @@ extractLinkerFlagsFromObjectFile(const llvm::object::WasmObjectFile *ObjectFile,
 static bool extractLinkerFlags(const llvm::object::Binary *Bin,
                                CompilerInstance &Instance,
                                StringRef BinaryFileName,
-                               std::vector<std::string> &LinkerFlags) {
+                               std::vector<std::string> &LinkerFlags,
+                               std::unordered_map<std::string, bool> &CommonAddedSwiftLibraries) {
   if (auto *ObjectFile = llvm::dyn_cast<llvm::object::ELFObjectFileBase>(Bin)) {
-    return extractLinkerFlagsFromObjectFile(ObjectFile, LinkerFlags, Instance);
+    return extractLinkerFlagsFromObjectFile(ObjectFile, LinkerFlags, CommonAddedSwiftLibraries, Instance);
   } else if (auto *ObjectFile =
                  llvm::dyn_cast<llvm::object::WasmObjectFile>(Bin)) {
-    return extractLinkerFlagsFromObjectFile(ObjectFile, LinkerFlags, Instance);
+    return extractLinkerFlagsFromObjectFile(ObjectFile, LinkerFlags, CommonAddedSwiftLibraries, Instance);
   } else if (auto *Archive = llvm::dyn_cast<llvm::object::Archive>(Bin)) {
     llvm::Error Error = llvm::Error::success();
     for (const auto &Child : Archive->children(Error)) {
@@ -197,7 +220,7 @@ static bool extractLinkerFlags(const llvm::object::Binary *Bin,
         return true;
       }
       if (extractLinkerFlags(ChildBinary->get(), Instance, BinaryFileName,
-                             LinkerFlags)) {
+                             LinkerFlags, CommonAddedSwiftLibraries)) {
         return true;
       }
     }
@@ -229,6 +252,13 @@ int autolink_extract_main(ArrayRef<const char *> Args, const char *Argv0,
 
   std::vector<std::string> LinkerFlags;
 
+  // Keep track of whether we've already added the common
+  // Swift libraries that ususally have autolink directives
+  // in most object fiels
+  std::unordered_map<std::string, bool> CommonAddedSwiftLibraries = {{"-lswiftSwiftOnoneSupport", false},
+                                                                    {"-lswiftCore", false},
+                                                                    {"-lswift_Concurrency", false}};
+
   // Extract the linker flags from the objects.
   for (const auto &BinaryFileName : Invocation.getInputFilenames()) {
     auto BinaryOwner = llvm::object::createBinary(BinaryFileName);
@@ -245,7 +275,7 @@ int autolink_extract_main(ArrayRef<const char *> Args, const char *Argv0,
     }
 
     if (extractLinkerFlags(BinaryOwner->getBinary(), Instance, BinaryFileName,
-                           LinkerFlags)) {
+                           LinkerFlags, CommonAddedSwiftLibraries)) {
       return 1;
     }
   }

test/AutolinkExtract/import.swift

@@ -2,9 +2,14 @@
 // RUN: %target-swiftc_driver -emit-module -emit-module-path %t/empty.swiftmodule -module-name empty -module-link-name empty %S/empty.swift
 // RUN: %target-swiftc_driver -c %s -I %t -o %t/import_experimental.o
 // RUN: %target-swift-autolink-extract %t/import_experimental.o -o - | %FileCheck --check-prefix CHECK-%target-object-format %s
+// RUN: %target-swiftc_driver -c %s -I %t -o %t/import_experimental_again.o
+// RUN: %target-swift-autolink-extract %t/import_experimental.o %t/import_experimental_again.o -o - | %FileCheck --check-prefix CHECK-%target-object-format %s
+// RUN: %target-swift-autolink-extract %t/import_experimental.o %t/import_experimental_again.o -o - | %FileCheck --check-prefix UNIQUE %s
 
 // REQUIRES: autolink-extract
 
+// UNIQUE-COUNT-1: -lswiftCore
+
 // CHECK-elf-DAG: -lswiftCore
 // CHECK-elf-DAG: -lempty