mac: use local dsymutil

The Xcode 9.3 dsymutil dies with "IO Error" when handling objects larger than
2**32 bytes; the upstream llvm one seems not to have this problem.

Bug: 780980
Change-Id: I6846383329bd28a65516c0ef3ad177e1a78d08f3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1500198
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#637756}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 99453a4326a2d09990877c4516a343028bf89f29

toolchain/mac/BUILD.gn

@@ -186,6 +186,12 @@ template("mac_toolchain") {
     # If dSYMs are enabled, this flag will be added to the link tools.
     if (_enable_dsyms) {
       dsym_switch = " -Wcrl,dsym,{{root_out_dir}} "
+      if (is_mac) {
+        dsym_switch += "-Wcrl,dsymutilpath," +
+                          rebase_path("//tools/clang/dsymutil/bin/dsymutil",
+                                      root_build_dir) + " "
+      }
+
       dsym_output_dir =
           "{{root_out_dir}}/{{target_output_name}}{{output_extension}}.dSYM"
       dsym_output = [

toolchain/mac/linker_driver.py

@@ -10,6 +10,8 @@ import shutil
 import subprocess
 import sys
 
+DSYMUTIL_INVOKE = ['xcrun', 'dsymutil']
+
 # The linker_driver.py is responsible for forwarding a linker invocation to
 # the compiler driver, while processing special arguments itself.
 #
@@ -31,6 +33,10 @@ import sys
 #         "... -o out/gn/obj/foo/libbar.dylib ... -Wcrl,dsym,out/gn ..."
 #       The resulting dSYM would be out/gn/libbar.dylib.dSYM/.
 #
+#   -Wcrl,dsymutilpath,<dsymutil_path>
+#       Sets the path to the dsymutil to run with -Wcrl,dsym, in which case
+#       `xcrun` is not used to invoke it.
+#
 #   -Wcrl,unstripped,<unstripped_path_prefix>
 #       After invoking the linker, and before strip, this will save a copy of
 #       the unstripped linker output in the directory unstripped_path_prefix.
@@ -142,10 +148,29 @@ def RunDsymUtil(dsym_path_prefix, full_args):
 
   # Remove old dSYMs before invoking dsymutil.
   _RemovePath(dsym_out)
-  subprocess.check_call(['xcrun', 'dsymutil', '-o', dsym_out, linker_out])
+  subprocess.check_call(DSYMUTIL_INVOKE + ['-o', dsym_out, linker_out])
   return [dsym_out]
 
 
+def SetDsymutilPath(dsymutil_path, full_args):
+  """Linker driver action for -Wcrl,dsymutilpath,<dsymutil_path>.
+
+  Sets the invocation command for dsymutil, which allows the caller to specify
+  an alternate dsymutil. This action is always processed before the RunDsymUtil
+  action.
+
+  Args:
+    dsymutil_path: string, The path to the dsymutil binary to run
+    full_args: list of string, Full argument list for the linker driver.
+
+  Returns:
+    No output - this step is run purely for its side-effect.
+  """
+  global DSYMUTIL_INVOKE
+  DSYMUTIL_INVOKE = [dsymutil_path]
+  return []
+
+
 def RunSaveUnstripped(unstripped_path_prefix, full_args):
   """Linker driver action for -Wcrl,unstripped,<unstripped_path_prefix>. Copies
   the linker output to |unstripped_path_prefix| before stripping.
@@ -219,6 +244,7 @@ order in which the actions are invoked. The first item in the tuple is the
 argument's -Wcrl,<sub_argument> and the second is the function to invoke.
 """
 _LINKER_DRIVER_ACTIONS = [
+    ('dsymutilpath,', SetDsymutilPath),
     ('dsym,', RunDsymUtil),
     ('unstripped,', RunSaveUnstripped),
     ('strip,', RunStrip),