Re: [PATCHES] Reorganization of spinlock defines

Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > He is uncomfortable with the port/*.h changes at this point, so it seems
> > I am going to have to add Itanium/Opteron tests to most of those files.
>
> Why don't you try to put together a proposed patch of that kind, and
> then we can look to see how big and ugly it is compared to the other?
> If the alternative is shown to be really messy, that would sway my
> opinion, maybe Marc's too.

OK, here is an Opteron/Itanium patch that might work. I say "might"
because I don't have a lot of confidence in the current spinlock
detection code. There is an uncoupling between the definition of
HAS_TEST_AND_SET, the data type used by slock_t, and the assembler code.

For example, here is darwin.h:

#if defined(__ppc__)
#define HAS_TEST_AND_SET
#endif

#if defined(__ppc__)
typedef unsigned int slock_t;

#else
typedef unsigned char slock_t;

#endif

Does this say that Darwin on something other than PPC doesn't have
spinlocks? Is that going to hit a spinlock define, or fall through?

Also, look at NEED_I386_TAS_ASM: It is used only by SCO compilers,
though it is defined for all Intel platforms. The s_lock.h gcc test
already tests __i386__. It really doesn't do anything on non-SCO
compilers, and non-SCO compilers are better testing for i386 anyway.

Also, Solaris has just this:

#define HAS_TEST_AND_SET
typedef unsigned char slock_t;

How do they know what CPU is being used? Both Sparc and i386 use
"unsigned char", so I guess it is OK, but I think you can see what I
mean when I say I don't have a lot of confidence in what we have now.

Let me also add that some slock_t typedef's didn't match the assembly
code. For example, __alpha_ on netbsd.h had slock_t defined as
"unsigned long", while in linux.h it was "long int". I assumed the
alpha was the correct one, but clearly they should be the same because
they use the same assembly code.

See what I mean.

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