Re: [PATCH] Add native windows on arm64 support - Mailing list pgsql-hackers

From Dave Cramer
Subject Re: [PATCH] Add native windows on arm64 support
Date
Msg-id CADK3HHLOAC1OnXKANLA5Z8=XPvmYV-_Nw9ejLxp0JBmmm6mZeQ@mail.gmail.com
Whole thread Raw
In response to Re: [PATCH] Add native windows on arm64 support  (Andrew Dunstan <andrew@dunslane.net>)
Responses Re: [PATCH] Add native windows on arm64 support
List pgsql-hackers


On Tue, 24 Sept 2024 at 14:31, Dave Cramer <davecramer@postgres.rocks> wrote:


On Tue, 13 Feb 2024 at 16:28, Dave Cramer <davecramer@postgres.rocks> wrote:



On Tue, 13 Feb 2024 at 12:52, Andres Freund <andres@anarazel.de> wrote:
Hi,

On 2024-02-13 12:49:33 -0500, Dave Cramer wrote:
> > I think I might have been on to something - if my human emulation of a
> > preprocessor isn't wrong, we'd end up with
> >
> > #define S_UNLOCK(lock)  \
> >         do { _ReadWriteBarrier(); (*(lock)) = 0; } while (0)
> >
> > on msvc + arm. And that's entirely insufficient - _ReadWriteBarrier() just
> > limits *compiler* level reordering, not CPU level reordering.  I think it's
> > even insufficient on x86[-64], but it's definitely insufficient on arm.
> >
> In fact ReadWriteBarrier has been deprecated _ReadWriteBarrier | Microsoft
> Learn
> <https://learn.microsoft.com/en-us/cpp/intrinsics/readwritebarrier?view=msvc-170>

I'd just ignore that, that's just pushing towards more modern stuff that's
more applicable to C++ than C.


> I did try using atomic_thread_fence as per atomic_thread_fence -
> cppreference.com
> <https://en.cppreference.com/w/c/atomic/atomic_thread_fence>

The semantics of atomic_thread_fence are, uh, very odd.  I'd just use
MemoryBarrier().

#define S_UNLOCK(lock)  \
    do { MemoryBarrier(); (*(lock)) = 0; } while (0)

#endif
 
Has no effect.

I have no idea if that is what you meant that I should do ?

Dave


Revisiting this:

Andrew, can you explain the difference between ninja test (which passes) and what the build farm does. The buildfarm crashes.

I have a dmp file with a stack trace if anyone is interested

Dave 

Dave 

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