commit bc021999c84690dc9e9acd231a7f04a769bb0d36
author Jez Ng <jezng@fb.com> Thu Mar 25 14:39:45 2021 -0400
committer Copybara-Service <copybara-worker@google.com> Thu Mar 25 13:34:50 2021 -0700
tree c3c3d91de095ae8bf9916fbc700ec93fb6c7da26
parent 028eea63292d5ec271c164a650d1a349cb6782b5

[lld-macho] Add support for --threads

Code and test are largely identical to the LLD-ELF equivalents.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D99312

GitOrigin-RevId: 0113cf00b6f43ebfa902447e6ee23f9b37021a16

MachO/Driver.cpp

diff --git a/MachO/Driver.cpp b/MachO/Driver.cpp
index 57ff369..35f3ddf 100644
--- a/MachO/Driver.cpp
+++ b/MachO/Driver.cpp
@@ -38,6 +38,7 @@
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Host.h"
 #include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/Parallel.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/TarWriter.h"
 #include "llvm/Support/TargetSelect.h"
@@ -861,6 +862,16 @@
   depTracker =
       make<DependencyTracker>(args.getLastArgValue(OPT_dependency_info, ""));
 
+  if (auto *arg = args.getLastArg(OPT_threads_eq)) {
+    StringRef v(arg->getValue());
+    unsigned threads = 0;
+    if (!llvm::to_integer(v, threads, 0) || threads == 0)
+      error(arg->getSpelling() + ": expected a positive integer, but got '" +
+            arg->getValue() + "'");
+    parallel::strategy = hardware_concurrency(threads);
+    // FIXME: use this to configure ThinLTO concurrency too
+  }
+
   config->entry = symtab->addUndefined(args.getLastArgValue(OPT_e, "_main"),
                                        /*file=*/nullptr,
                                        /*isWeakRef=*/false);

MachO/Options.td

diff --git a/MachO/Options.td b/MachO/Options.td
index 073cb5b..cdb8a46 100644
--- a/MachO/Options.td
+++ b/MachO/Options.td
@@ -20,6 +20,9 @@
     HelpText<"Use colors in diagnostics (default: auto)">,
     MetaVarName<"[auto,always,never]">,
     Group<grp_lld>;
+def threads_eq : Joined<["--"], "threads=">,
+    HelpText<"Number of threads. '1' disables multi-threading. By default all available hardware threads are used">,
+    Group<grp_lld>;
 def reproduce: Separate<["--"], "reproduce">,
     Group<grp_lld>;
 def reproduce_eq: Joined<["--"], "reproduce=">,

test/MachO/threads.s

diff --git a/test/MachO/threads.s b/test/MachO/threads.s
new file mode 100644
index 0000000..b317638
--- /dev/null
+++ b/test/MachO/threads.s
@@ -0,0 +1,16 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %s -o %t.o
+
+## A positive integer is allowed.
+# RUN: %lld --threads=1 %t.o -o /dev/null
+# RUN: %lld --threads=2 %t.o -o /dev/null
+
+# RUN: not %lld --threads=all %t.o -o /dev/null 2>&1 | FileCheck %s -DN=all
+# RUN: not %lld --threads=0 %t.o -o /dev/null 2>&1 | FileCheck %s -DN=0
+# RUN: not %lld --threads=-1 %t.o -o /dev/null 2>&1 | FileCheck %s -DN=-1
+
+# CHECK: error: --threads=: expected a positive integer, but got '[[N]]'
+
+.globl _main
+_main:
+  ret