lld: add basic static library search

[compnerd]

Summary

This is a very basic static library search addition. This is the pre-Xcode4 behaviour of searching all paths for the shared version before searching for the static version of the library. This behaviour is supposed to be inverted with -search_paths_first being the default. This adds the library search with the intention of providing the setup to merge the paths into one path and making it controllable by OPT_search_paths_first.

[compnerd]

I do have the follow up fix that this really begs for. I figure that doing it in slower incremental steps is easier, but Im okay with either doing it in two steps or keeping it a single step.

[int3]

Doing it in two steps is fine :)

lld/test/MachO/static-link.s

3–5

The inclusion of a dylib symbol here seems unrelated to the static linking behavior. Let's try to keep the tests as targeted as possible. Also, static GOTPCREL relocations won't work correctly before D80857: [lld-macho] Handle GOT relocations of non-dylib symbols lands. I think we should just do normal symbol lookup (i.e. X86_64_RELOC_SIGNED), and use llvm-objdump --section-headers --syms -d to check that the resulting code has the correct relocated addresses. relocation.s should be a good reference.

10

we usually put this as the first line in the file

[compnerd]

Update test

[int3]

LGTM, thanks!

lld/test/MachO/static-link.s

25–30

nit: we usually put these right after their respective FileCheck invocation line (so after line 11 in this file)

[int3]

lld/test/MachO/static-link.s

17–20

one more nit: would be nice to clean up the indentation of these comments

[compnerd]

lld/test/MachO/static-link.s

17–20

Oh, they are just aligned (with hard tabs as is the general pattern with assembly files), I can change them to be indented with space instead.

25–30

Hmm, most of LLVM IIRC also tends to just group the expectations and the RUN lines so that its easier to understand the full flow of the test.

[compnerd]

rG116e38fd8b89fb20279cbf7edb4a49a7ab5c7764

[gkm]

lld/MachO/Driver.cpp

299–302

You have implemented old -search_dylibs_first semantics. The default since Xcode 4 is -search_paths_first

[smeenai]

Could you upload with full context? It's hard to read this as-is.

[smeenai]

Oops, wrong one.

[gkm]

lld/MachO/Driver.cpp

299–302

Nevermind. I see D81124 fixes it.

lld/MachO/Driver.cpp

     if (fs::exists(path))
       return path;
   }
-  error("library not found for -l" + name);
+  return None;
+}
+
+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;
+  }
   return None;
 }
 

     case OPT_INPUT:
       addFile(arg->getValue());
       break;
-    case OPT_l:
-      if (Optional<std::string> path = findDylib(arg->getValue()))
+    case OPT_l: {
+      StringRef name = arg->getValue();
+      if (Optional<std::string> path = findDylib(name))
+        addFile(*path);
+      else if (Optional<std::string> path = findArchive(name))
         addFile(*path);
+      else
+        error("library not found for -l" + name);
       break;
+    }
     case OPT_platform_version: {
       handlePlatformVersion(it, end); // Can advance "it".
       break;

lld/test/MachO/static-link.s

+# REQUIRES: x86
+
+# RUN: mkdir -p %t
+#
+# RUN: llvm-mc -filetype obj -triple x86_64-apple-darwin %p/Inputs/libgoodbye.s -o %t/goodbye.o
+# 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 -lgoodbye %t/test.o
+#
+# RUN: llvm-objdump --syms -d -r %t/test | FileCheck %s
+
+.section __TEXT,__text
+.global _main
+
+_main:
+  movl $0x2000004, %eax                                # write()
+  mov $1, %rdi                                 # stdout
+  leaq _goodbye_world(%rip), %rsi
+  mov $15, %rdx                                        # length
+  syscall
+  mov $0, %rax
+  ret
+
+# CHECK: SYMBOL TABLE:
+# CHECK: {{0+}}[[ADDR:[0-9a-f]+]] g     O __TEXT,__cstring _goodbye_world
+
+# CHECK: Disassembly of section __TEXT,__text
+# CHECK-LABEL: <_main>:
+# CHECK: leaq {{.*}}(%rip), %rsi   # [[ADDR]] <_goodbye_world>