Further tidy-up for old CPU architectures.

Further to commit 92d70b77, let's drop the code we carry for the
following untested architectures: M68K, M88K, M32R, SuperH.  We have no
idea if anything actually works there, and surely as vintage hardware
and microcontrollers they would be underpowered for modern purposes.

We could always consider re-adding SuperH based on evidence of usage and
build farm support, if someone shows up to provide it.

While here, SPARC is usually written in all caps.

Suggested-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Robert Haas <robertmhaas@gmail.com> (the idea, not the patch)
Discussion: https://postgr.es/m/959917.1657522169%40sss.pgh.pa.us

doc/src/sgml/installation.sgml

@@ -2125,11 +2125,10 @@ export MANPATH
 
   <para>
    In general, <productname>PostgreSQL</productname> can be expected to work on
-   these CPU architectures: x86, PowerPC, S/390, Sparc, ARM, MIPS, RISC-V,
+   these CPU architectures: x86, PowerPC, S/390, SPARC, ARM, MIPS, RISC-V,
    and PA-RISC, including
    big-endian, little-endian, 32-bit, and 64-bit variants where applicable.
-   Code support exists for M68K, M88K, M32R, and SuperH, but these
-   architectures are not known to have been tested recently.  It is often
+   It is often
    possible to build on an unsupported CPU type by configuring with
    <option>--disable-spinlocks</option>, but performance will be poor.
   </para>

src/backend/storage/lmgr/s_lock.c

@@ -220,71 +220,6 @@ update_spins_per_delay(int shared_spins_per_delay)
 }
 
 
-/*
- * Various TAS implementations that cannot live in s_lock.h as no inline
- * definition exists (yet).
- * In the future, get rid of tas.[cso] and fold it into this file.
- *
- * If you change something here, you will likely need to modify s_lock.h too,
- * because the definitions for these are split between this file and s_lock.h.
- */
-
-
-#ifdef HAVE_SPINLOCKS			/* skip spinlocks if requested */
-
-
-#if defined(__GNUC__)
-
-/*
- * All the gcc flavors that are not inlined
- */
-
-
-/*
- * Note: all the if-tests here probably ought to be testing gcc version
- * rather than platform, but I don't have adequate info to know what to
- * write.  Ideally we'd flush all this in favor of the inline version.
- */
-#if defined(__m68k__) && !defined(__linux__)
-/* really means: extern int tas(slock_t* **lock); */
-static void
-tas_dummy()
-{
-	__asm__ __volatile__(
-#if (defined(__NetBSD__) || defined(__OpenBSD__)) && defined(__ELF__)
-/* no underscore for label and % for registers */
-						 "\
-.global		tas 				\n\
-tas:							\n\
-			movel	%sp@(0x4),%a0	\n\
-			tas 	%a0@		\n\
-			beq 	_success	\n\
-			moveq	#-128,%d0	\n\
-			rts 				\n\
-_success:						\n\
-			moveq	#0,%d0		\n\
-			rts 				\n"
-#else
-						 "\
-.global		_tas				\n\
-_tas:							\n\
-			movel	sp@(0x4),a0	\n\
-			tas 	a0@			\n\
-			beq 	_success	\n\
-			moveq 	#-128,d0	\n\
-			rts					\n\
-_success:						\n\
-			moveq 	#0,d0		\n\
-			rts					\n"
-#endif							/* (__NetBSD__ || __OpenBSD__) && __ELF__ */
-		);
-}
-#endif							/* __m68k__ && !__linux__ */
-#endif							/* not __GNUC__ */
-#endif							/* HAVE_SPINLOCKS */
-
-
-
 /*****************************************************************************/
 #if defined(S_LOCK_TEST)
 

src/include/storage/s_lock.h

@@ -498,56 +498,6 @@ do \
 #endif /* powerpc */
 
 
-/* Linux Motorola 68k */
-#if (defined(__mc68000__) || defined(__m68k__)) && defined(__linux__)
-#define HAS_TEST_AND_SET
-
-typedef unsigned char slock_t;
-
-#define TAS(lock) tas(lock)
-
-static __inline__ int
-tas(volatile slock_t *lock)
-{
-	register int rv;
-
-	__asm__	__volatile__(
-		"	clrl	%0		\n"
-		"	tas		%1		\n"
-		"	sne		%0		\n"
-:		"=d"(rv), "+m"(*lock)
-:		/* no inputs */
-:		"memory", "cc");
-	return rv;
-}
-
-#endif	 /* (__mc68000__ || __m68k__) && __linux__ */
-
-
-/* Motorola 88k */
-#if defined(__m88k__)
-#define HAS_TEST_AND_SET
-
-typedef unsigned int slock_t;
-
-#define TAS(lock) tas(lock)
-
-static __inline__ int
-tas(volatile slock_t *lock)
-{
-	register slock_t _res = 1;
-
-	__asm__ __volatile__(
-		"	xmem	%0, %2, %%r0	\n"
-:		"+r"(_res), "+m"(*lock)
-:		"r"(lock)
-:		"memory");
-	return (int) _res;
-}
-
-#endif	 /* __m88k__ */
-
-
 #if defined(__mips__) && !defined(__sgi)	/* non-SGI MIPS */
 #define HAS_TEST_AND_SET
 
@@ -619,58 +569,6 @@ do \
 #endif /* __mips__ && !__sgi */
 
 
-#if defined(__m32r__) && defined(HAVE_SYS_TAS_H)	/* Renesas' M32R */
-#define HAS_TEST_AND_SET
-
-#include <sys/tas.h>
-
-typedef int slock_t;
-
-#define TAS(lock) tas(lock)
-
-#endif /* __m32r__ */
-
-
-#if defined(__sh__)				/* Renesas' SuperH */
-#define HAS_TEST_AND_SET
-
-typedef unsigned char slock_t;
-
-#define TAS(lock) tas(lock)
-
-static __inline__ int
-tas(volatile slock_t *lock)
-{
-	register int _res;
-
-	/*
-	 * This asm is coded as if %0 could be any register, but actually SuperH
-	 * restricts the target of xor-immediate to be R0.  That's handled by
-	 * the "z" constraint on _res.
-	 */
-	__asm__ __volatile__(
-		"	tas.b @%2    \n"
-		"	movt  %0     \n"
-		"	xor   #1,%0  \n"
-:		"=z"(_res), "+m"(*lock)
-:		"r"(lock)
-:		"memory", "t");
-	return _res;
-}
-
-#endif	 /* __sh__ */
-
-
-/* These live in s_lock.c, but only for gcc */
-
-
-#if defined(__m68k__) && !defined(__linux__)	/* non-Linux Motorola 68k */
-#define HAS_TEST_AND_SET
-
-typedef unsigned char slock_t;
-#endif
-
-
 #if defined(__hppa) || defined(__hppa__)	/* HP PA-RISC */
 /*
  * HP's PA-RISC