compiler options for building OpenSSL dependency on Windows

[richardlau]

• Version: master
• Platform: Windows
• Subsystem: build, deps

As per #31311 (comment) it looks like gyp ignores cflags on Windows when generating for Visual Studio (msvs) so the following from our gyp files for OpenSSL are currently ignored:

node/deps/openssl/openssl_common.gypi

Lines 32 to 34 in be46a72

	'cflags': [
	'-W3', '-wd4090', '-Gs0', '-GF', '-Gy', '-nologo','/O2',
	],

These settings appear to mirror those in OpenSSL's own build configuration:

node/deps/openssl/openssl/Configurations/10-main.conf

Line 1219 in be055d1

CFLAGS => "/W3 /wd4090 /nologo",

node/deps/openssl/openssl/Configurations/10-main.conf

Lines 1242 to 1252 in be055d1

	CFLAGS => add(picker(debug => '/Od',
	release => '/O2')),
	cflags => add(picker(default => '/Gs0 /GF /Gy',
	debug =>
	sub {
	($disabled{shared} ? "" : "/MDd");
	},
	release =>
	sub {
	($disabled{shared} ? "" : "/MD");
	})),

In practice we appear to be getting most of these via settings in our common.gypi. For the ones we aren't explicitly setting I don't know enough about Windows for the -Gs0 case to know if this is an issue we want to address (cc @nodejs/platform-windows).

Options we already set

-W3

from

node/common.gypi

Line 229 in f4797ff

'WarningLevel': 3, # /W3

(refs: VCCLCompilerTool.WarningLevel Property)

-GF

from

node/common.gypi

Line 226 in fe05818

'StringPooling': 'true', # pool string literals

(refs: VCCLCompilerTool.StringPooling Property)

-Gy

from

node/common.gypi

Line 196 in be46a72

'EnableFunctionLevelLinking': 'true',

(refs: VCCLCompilerTool.EnableFunctionLevelLinking Property)

-nologo

from

node/common.gypi

Line 227 in fe05818

'SuppressStartupBanner': 'true',

(refs: VCCLCompilerTool.SuppressStartupBanner Property)

Options we don't currently explicitly set

-wd4090

being addressed by #31311

-Gs0

I don't know if there's a good reason that OpenSSL sets this. The MSDN docs says

/Gs0 initiates stack probes for every function call that requires storage for local variables. This can have a negative impact on performance.

/O2

We currently set

node/common.gypi

Line 201 in fe05818

'Optimization': 3, # /Ox, full optimization

(refs: VCCLCompilerTool.Optimization Property) which maps 3 to /Ox and /Ox:

The /Ox compiler option enables the /O compiler options that favor speed. The /Ox compiler option does not include the additional /GF (Eliminate Duplicate Strings) and /Gy (Enable Function-Level Linking) options enabled by /O1 or /O2 (Minimize Size, Maximize Speed).

but we switch on /GF and /Gy via StringPooling and EnableFunctionLevelLinking above so this works out?

[jasnell]

Ping @richardlau ... any progress on this?

[richardlau]

¯\_(ツ)_/¯ I still don't know if we should be setting the compiler options that OpenSSL uses but we do not.

Let's close.