Re: [PATCH] Fix ARM64/MSVC atomic memory ordering issues on Win11 by adding explicit DMB ​barriers

On Thu, Nov 20, 2025, at 7:08 PM, Thomas Munro wrote:
> If you have an environment set up so it's easy to test, I would also
> be very interested to know if my patch set[3] that nukes all this
> stuff and includes <stdatomic.h> instead, which is green on
> Windows/x86 CI, will just work™ there too.
>
> [3]
> https://www.postgresql.org/message-id/flat/CA%2BhUKGKFvu3zyvv3aaj5hHs9VtWcjFAmisOwOc7aOZNc5AF3NA%40mail.gmail.com

Hello Thomas,

I gave your stdatomic patchs a try, here's where it fell apart linking.

[174/1996] Linking target src/interfaces/libpq/libpq.dll
Creating library src/interfaces/libpq\libpq.lib
[981/1996] Linking target src/interfaces/ecpg/pgtypeslib/libpgtypes.dll
Creating library src\interfaces\ecpg\pgtypeslib\libpgtypes.lib
[1235/1996] Linking target src/interfaces/ecpg/ecpglib/libecpg.dll
Creating library src\interfaces\ecpg\ecpglib\libecpg.lib
[1401/1996] Linking target src/backend/postgres.exe
FAILED: [code=1120] src/backend/postgres.exe src/backend/postgres.pdb
"link" @src/backend/postgres.exe.rsp
Creating library src\backend\postgres.lib
storage_lmgr_s_lock.c.obj : error LNK2019: unresolved external symbol _mm_pause referenced in function perform_spin_delay
src\backend\postgres.exe : fatal error LNK1120: 1 unresolved externals
[1410/1996] Compiling C object src/backend/snowball/dict_snowball.dll.p/libstemmer_stem_UTF_8_german.c.obj
ninja: build stopped: subcommand failed.

I used your v2 and the attached reduced set of Dave and my changes. I'll work on this next week if I find a bit of time, shouldn't be all that hard. I thought I'd update you before then. Also attached is my config script, I sent out my notes on a separate email.

I forgot to provide the MSVC compiler/linker versions for posterity, they are:
cl (msvc 19.50.35718 "Microsoft (R) C/C++ Optimizing Compiler Version 19.50.35718 for ARM64")
link 14.50.35718.0

best.

-greg