From e78431354bcb6bec5be9adf4ea37d860445f8c16 Mon Sep 17 00:00:00 2001
From: Saleem Abdulrasool <compnerd@compnerd.org>
Date: Thu, 4 Jun 2020 17:40:41 -0700
Subject: [PATCH] lld: use modern library search ordering

This merges the static and shared library and behaves as if
`-search_paths_first` was specified which is also the default behaviour
on ld64 (and now lld). Unify the paths, and use `llvm::sys::path` to
deal with the path to be truly agnostic to the host.
---
 lld/MachO/Driver.cpp               | 32 ++++++++++------------
 lld/test/MachO/link-search-order.s | 43 ++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+), 18 deletions(-)
 create mode 100644 lld/test/MachO/link-search-order.s

diff --git a/lld/MachO/Driver.cpp b/lld/MachO/Driver.cpp
index 723c62c39185..e0ebf8e5710f 100644
--- a/lld/MachO/Driver.cpp
+++ b/lld/MachO/Driver.cpp
@@ -73,21 +73,18 @@ opt::InputArgList MachOOptTable::parse(ArrayRef<const char *> argv) {
   return args;
 }
 
-// This is for -lfoo. We'll look for libfoo.dylib from search paths.
-static Optional<std::string> findDylib(StringRef name) {
-  for (StringRef dir : config->searchPaths) {
-    std::string path = (dir + "/lib" + name + ".dylib").str();
-    if (fs::exists(path))
-      return path;
-  }
-  return None;
-}
+static Optional<std::string> findLibrary(StringRef name) {
+  std::string shared = (llvm::Twine("lib") + name + ".dylib").str();
+  std::string archive = (llvm::Twine("lib") + name + ".a").str();
+  llvm::SmallString<260> location;
 
-static Optional<std::string> findArchive(StringRef name) {
   for (StringRef dir : config->searchPaths) {
-    std::string path = (dir + "/lib" + name + ".a").str();
-    if (fs::exists(path))
-      return path;
+    for (StringRef library : {shared, archive}) {
+      location = dir;
+      llvm::sys::path::append(location, library);
+      if (fs::exists(location))
+        return location.str().str();
+    }
   }
   return None;
 }
@@ -296,12 +293,11 @@ bool macho::link(llvm::ArrayRef<const char *> argsArr, bool canExitEarly,
       break;
     case OPT_l: {
       StringRef name = arg->getValue();
-      if (Optional<std::string> path = findDylib(name))
+      if (Optional<std::string> path = findLibrary(name)) {
         addFile(*path);
-      else if (Optional<std::string> path = findArchive(name))
-        addFile(*path);
-      else
-        error("library not found for -l" + name);
+        break;
+      }
+      error("library not found for -l" + name);
       break;
     }
     case OPT_platform_version: {
diff --git a/lld/test/MachO/link-search-order.s b/lld/test/MachO/link-search-order.s
new file mode 100644
index 000000000000..289293a8cb47
--- /dev/null
+++ b/lld/test/MachO/link-search-order.s
@@ -0,0 +1,43 @@
+# REQUIRES: x86
+
+# RUN: mkdir -p %t
+#
+# RUN: llvm-mc -filetype obj -triple x86_64-apple-darwin %p/Inputs/libhello.s -o %t/hello.o
+# RUN: lld -flavor darwinnew -dylib -install_name @executable_path/libhello.dylib %t/hello.o -o %t/libhello.dylib
+#
+# RUN: llvm-mc -filetype obj -triple x86_64-apple-darwin %p/Inputs/libgoodbye.s -o %t/goodbye.o
+# RUN: lld -flavor darwinnew -dylib -install_name @executable_path/libgoodbye.dylib %t/goodbye.o -o %t/libgoodbye.dylib
+# RUN: llvm-ar --format=darwin crs %t/libgoodbye.a %t/goodbye.o
+#
+# RUN: llvm-mc -filetype obj -triple x86_64-apple-darwin %s -o %t/test.o
+# RUN: lld -flavor darwinnew -o %t/test -Z -L%t -lhello -lgoodbye %t/test.o
+#
+# RUN: llvm-objdump --macho --dylibs-used %t/test | FileCheck %s
+
+# CHECK: @executable_path/libhello.dylib
+# CHECK: @executable_path/libgoodbye.dylib
+# CHECK: /usr/lib/libSystem.B.dylib
+
+.section __TEXT,__text
+.global _main
+
+_main:
+  movl $0x2000004, %eax                         # write()
+  mov $1, %rdi                                  # stdout
+  movq _hello_world@GOTPCREL(%rip), %rsi
+  mov $13, %rdx                                 # length
+  syscall
+
+  movl $0x2000004, %eax                         # write()
+  mov $1, %rdi                                  # stdout
+  movq _hello_its_me@GOTPCREL(%rip), %rsi
+  mov $15, %rdx                                 # length
+  syscall
+
+  movl $0x2000004, %eax                         # write()
+  mov $1, %rdi                                  # stdout
+  movq _goodbye_world@GOTPCREL(%rip), %rsi
+  mov $15, %rdx                                 # length
+  syscall
+  mov $0, %rax
+  ret