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build: add support for section ordering #35272

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0e5a828
build: add support for section ordering
Jan 6, 2020
dff2255
address review comments
Sep 29, 2020
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build: add support for section ordering 
Adds support for using a section ordering file with the gold linker.
This makes it possible to reorder functions in a build to optimize for
a specific workload.

`hfsort` is a tool that can be used to generate such a file from perf-
recorded last branch record (LBR) data by running Node.js as
`node --perf-basic-prof`.

Refs: https://github.com/facebook/hhvm/tree/9966d482c19c6120c621c6f3896525fb19fb3842/hphp/tools/hfsort
Refs: https://software.intel.com/content/www/us/en/develop/articles/runtime-optimization-blueprint-IA-optimization-with-last-branch-record.html
Refs: #16891
Signed-off-by: Gabriel Schulhof <gabriel.schulhof@intel.com>
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Gabriel Schulhof committed Sep 21, 2020
commit 0e5a828f629bd4c3541301854c6c06670da47a6b
10 changes: 10 additions & 0 deletions common.gypi
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Expand Up @@ -172,6 +172,16 @@
},
'cflags': [ '-O3' ],
'conditions': [
['node_section_ordering_file!="-"', {
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@richardlau richardlau Sep 19, 2020

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Since common.gypi is also used to compile addons any variables referenced needs to have default values so addons can be compiled with older versions of Node.js where the variable isn’t present. See #33688 for an example.

'cflags': [
'-fuse-ld=gold',
'-ffunction-sections',
],
'ldflags': [
'-fuse-ld=gold',
'-Wl,--section-ordering-file=<(node_section_ordering_file)',
]
}],
['OS=="solaris"', {
# pull in V8's postmortem metadata
'ldflags': [ '-Wl,-z,allextract' ]
Expand Down
32 changes: 32 additions & 0 deletions configure.py
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Expand Up @@ -502,6 +502,14 @@
dest='node_use_large_pages_script_lld',
help='This option has no effect. --use-largepages is now a runtime option.')

parser.add_option('--use-section-ordering-file',
action='store',
dest='node_section_ordering_file',
default='',
help='Pass a section ordering file to the linker. This requires that ' +
'Node.js be linked using the gold linker. The gold linker must have ' +
'version 1.2 or greater.')

intl_optgroup.add_option('--with-intl',
action='store',
dest='with_intl',
Expand Down Expand Up @@ -1766,6 +1774,29 @@ def configure_inspector(o):
options.without_ssl)
o['variables']['v8_enable_inspector'] = 0 if disable_inspector else 1

def configure_section_file(o):
try:
proc = subprocess.Popen(['ld.gold'] + ['-v'], stdin = subprocess.PIPE,
stdout = subprocess.PIPE, stderr = subprocess.PIPE)
except OSError:
return 0
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match = re.match(r"^GNU gold.*([0-9]+)\.([0-9]+)$",
proc.communicate()[0].decode("utf-8"))

if match:
gold_major_version = match.group(1)
gold_minor_version = match.group(2)
if int(gold_major_version) == 1 and int(gold_minor_version) <= 1:
error('''GNU gold version must be greater than 1.2 in order to use section
reordering''')

if options.node_section_ordering_file != "":
o['variables']['node_section_ordering_file'] = os.path.realpath(
str(options.node_section_ordering_file))
else:
# An empty string here will cause gyp to fail.
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@bnoordhuis bnoordhuis Sep 20, 2020

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That's because gyp handles variables ending in _file (and _dir and _path) specially. Rename it and it should work without this workaround.

o['variables']['node_section_ordering_file'] = "-"

def make_bin_override():
if sys.platform == 'win32':
Expand Down Expand Up @@ -1831,6 +1862,7 @@ def make_bin_override():
configure_intl(output)
configure_static(output)
configure_inspector(output)
configure_section_file(output)

# Forward OSS-Fuzz settings
output['variables']['ossfuzz'] = b(options.ossfuzz)
Expand Down