Output a linker map file for official builds

build/toolchain/gcc_toolchain.gni

Index: build/toolchain/gcc_toolchain.gni
diff --git a/build/toolchain/gcc_toolchain.gni b/build/toolchain/gcc_toolchain.gni
index b31980668d89732523e9765f83e2e24f7caf1a4d..21985f88852ed678f085bdcb011f59d49234e0be 100644
--- a/build/toolchain/gcc_toolchain.gni
+++ b/build/toolchain/gcc_toolchain.gni
@@ -214,6 +214,9 @@ template("gcc_toolchain") {
       extra_ldflags = ""
     }
 
+    enable_linker_map =
+        defined(invoker.enable_linker_map) && invoker.enable_linker_map
+
     # These library switches can apply to all tools below.
     lib_switch = "-l"
     lib_dir_switch = "-L"
@@ -319,18 +322,27 @@ template("gcc_toolchain") {
 
       link_command = "$ld -shared {{ldflags}}${extra_ldflags} -o \"$unstripped_sofile\" -Wl,-soname=\"$soname\" @\"$rspfile\""
 
+      # Generate a map file to be used for binary size analysis.
+      # Map file adds ~10% to the link time on a z620.
+      # With target_os="android", libchrome.so.map.gz is ~20MB.
+      map_switch = ""
+      if (enable_linker_map && is_official_build) {
+        map_file = "$unstripped_sofile.map.gz"
+        map_switch = " --map-file \"$map_file\""
+      }
+
       assert(defined(readelf), "to solink you must have a readelf")
       assert(defined(nm), "to solink you must have an nm")
       strip_switch = ""
       if (defined(invoker.strip)) {
-        strip_switch = "--strip=${invoker.strip}"
+        strip_switch = "--strip=${invoker.strip} "
       }
 
       # This needs a Python script to avoid using a complex shell command
       # requiring sh control structures, pipelines, and POSIX utilities.
       # The host might not have a POSIX shell and utilities (e.g. Windows).
       solink_wrapper = rebase_path("//build/toolchain/gcc_solink_wrapper.py")
-      command = "$python_path \"$solink_wrapper\" --readelf=\"$readelf\" --nm=\"$nm\" $strip_switch --sofile=\"$unstripped_sofile\" --tocfile=\"$tocfile\" --output=\"$sofile\"$whitelist_flag -- $link_command"
+      command = "$python_path \"$solink_wrapper\" --readelf=\"$readelf\" --nm=\"$nm\" $strip_switch--sofile=\"$unstripped_sofile\" --tocfile=\"$tocfile\"$map_switch --output=\"$sofile\"$whitelist_flag -- $link_command"
 
       rspfile_content = "-Wl,--whole-archive {{inputs}} {{solibs}} -Wl,--no-whole-archive $solink_libs_section_prefix {{libs}} $solink_libs_section_postfix"
 
@@ -365,6 +377,9 @@ template("gcc_toolchain") {
       if (sofile != unstripped_sofile) {
         outputs += [ unstripped_sofile ]
       }
+      if (defined(map_file)) {
+        outputs += [ map_file ]
+      }
       link_output = sofile
       depend_output = tocfile
     }
@@ -433,12 +448,25 @@ template("gcc_toolchain") {
         unstripped_outfile = "{{root_out_dir}}/exe.unstripped/$exename"
       }
 
-      command = "$ld {{ldflags}}${extra_ldflags} -o \"$unstripped_outfile\" -Wl,--start-group @\"$rspfile\" {{solibs}} -Wl,--end-group $libs_section_prefix {{libs}} $libs_section_postfix"
+      # Generate a map file to be used for binary size analysis.
+      # Map file adds ~10% to the link time on a z620.
+      # With target_os="android", libchrome.so.map.gz is ~20MB.
+      map_switch = ""
+      if (enable_linker_map && is_official_build) {
+        map_file = "$unstripped_outfile.map.gz"
+        map_switch = " --map-file \"$map_file\""
+      }
+
+      link_command = "$ld {{ldflags}}${extra_ldflags} -o \"$unstripped_outfile\" -Wl,--start-group @\"$rspfile\" {{solibs}} -Wl,--end-group $libs_section_prefix {{libs}} $libs_section_postfix"
+
+      strip_switch = ""
       if (defined(invoker.strip)) {
-        link_wrapper =
-            rebase_path("//build/toolchain/gcc_link_wrapper.py", root_build_dir)
-        command = "$python_path \"$link_wrapper\" --strip=\"${invoker.strip}\" --unstripped-file=\"$unstripped_outfile\" --output=\"$outfile\" -- $command"
+        strip_switch = " --strip=\"${invoker.strip}\" --unstripped-file=\"$unstripped_outfile\""
       }
+
+      link_wrapper =
+          rebase_path("//build/toolchain/gcc_link_wrapper.py", root_build_dir)
+      command = "$python_path \"$link_wrapper\" --output=\"$outfile\"$strip_switch$map_switch -- $link_command"
       description = "LINK $outfile"
       rspfile_content = "{{inputs}}"
       outputs = [
@@ -450,6 +478,9 @@ template("gcc_toolchain") {
       if (defined(invoker.link_outputs)) {
         outputs += invoker.link_outputs
       }
+      if (defined(map_file)) {
+        outputs += [ map_file ]
+      }
     }
 
     # These two are really entirely generic, but have to be repeated in
@@ -511,7 +542,11 @@ template("clang_toolchain") {
     ar = "${toolprefix}ar"
     nm = "${toolprefix}nm"
 
-    forward_variables_from(invoker, [ "strip" ])
+    forward_variables_from(invoker,
+                           [
+                             "enable_linker_map",
+                             "strip",
+                           ])
 
     toolchain_args = {
       if (defined(invoker.toolchain_args)) {