Re: PR/56839: GCC emits wrong codes for compare_and_swap_1 bultins on armv5 (el & eb)

["Martin Husemann via gnats" <gnats-admin%NetBSD.org@localhost>]

The following reply was made to PR port-arm/56839; it has been noted by GNATS.

From: Martin Husemann <martin%duskware.de@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: PR/56839: GCC emits wrong codes for compare_and_swap_1 bultins
 on armv5 (el & eb)
Date: Thu, 19 Mar 2026 20:45:31 +0100

 Here is a patch that seems to work (builds, and makes the xfail tests
 work).
 
 Did I miss anything else?
 
 Martin
 
 
 
 Index: atomic_cas_16_cas.c
 ===================================================================
 RCS file: /cvsroot/src/common/lib/libc/atomic/atomic_cas_16_cas.c,v
 retrieving revision 1.3
 diff -u -p -r1.3 atomic_cas_16_cas.c
 --- atomic_cas_16_cas.c	21 Feb 2014 16:06:48 -0000	1.3
 +++ atomic_cas_16_cas.c	19 Mar 2026 19:44:18 -0000
 @@ -36,12 +36,15 @@
  #endif
  #include <sys/atomic.h>
  
 -bool bool_compare_and_swap_2(volatile uint16_t *, uint16_t, uint16_t, ...)
 +bool bool_compare_and_swap_2(volatile int16_t *, int16_t, int16_t, ...)
      asm("__sync_bool_compare_and_swap_2");
  
  bool
 -bool_compare_and_swap_2(volatile uint16_t *addr, uint16_t oldval,
 -	uint16_t newval, ...)
 +bool_compare_and_swap_2(volatile int16_t *addr, int16_t oldval,
 +	int16_t newval, ...)
  {
 -	return atomic_cas_16(addr, oldval, newval) == oldval;
 +	const uint16_t oldv = (uint16_t)oldval;
 +	const uint16_t newv = (uint16_t)newval;
 +
 +	return atomic_cas_16((volatile uint16_t *)addr, oldv, newv) == oldv;
  }
 Index: atomic_cas_32_cas.c
 ===================================================================
 RCS file: /cvsroot/src/common/lib/libc/atomic/atomic_cas_32_cas.c,v
 retrieving revision 1.2
 diff -u -p -r1.2 atomic_cas_32_cas.c
 --- atomic_cas_32_cas.c	8 Jan 2026 08:55:25 -0000	1.2
 +++ atomic_cas_32_cas.c	19 Mar 2026 19:44:18 -0000
 @@ -37,12 +37,15 @@
  
  #include <sys/atomic.h>
  
 -bool bool_compare_and_swap_4(volatile uint32_t *, uint32_t, uint32_t, ...)
 +bool bool_compare_and_swap_4(volatile int32_t *, int32_t, int32_t, ...)
      asm("__sync_bool_compare_and_swap_4");
  
  bool
 -bool_compare_and_swap_4(volatile uint32_t *addr, uint32_t oldval,
 -	uint32_t newval, ...)
 +bool_compare_and_swap_4(volatile int32_t *addr, int32_t oldval,
 +	int32_t newval, ...)
  {
 -	return atomic_cas_32(addr, oldval, newval) == oldval;
 +	const uint32_t oldv = (uint32_t)oldval;
 +	const uint32_t newv = (uint32_t)newval;
 +
 +	return atomic_cas_32((volatile uint32_t *)addr, oldv, newv) == oldv;
  }
 Index: atomic_cas_64_cas.c
 ===================================================================
 RCS file: /cvsroot/src/common/lib/libc/atomic/atomic_cas_64_cas.c,v
 retrieving revision 1.3
 diff -u -p -r1.3 atomic_cas_64_cas.c
 --- atomic_cas_64_cas.c	8 Jan 2026 08:55:25 -0000	1.3
 +++ atomic_cas_64_cas.c	19 Mar 2026 19:44:18 -0000
 @@ -39,14 +39,17 @@
  
  #ifdef __HAVE_ATOMIC64_OPS
  
 -bool bool_compare_and_swap_8(volatile uint64_t *, uint64_t, uint64_t, ...)
 +bool bool_compare_and_swap_8(volatile int64_t *, int64_t, int64_t, ...)
      asm("__sync_bool_compare_and_swap_8");
  
  bool
 -bool_compare_and_swap_8(volatile uint64_t *addr, uint64_t oldval,
 -	uint64_t newval, ...)
 +bool_compare_and_swap_8(volatile int64_t *addr, int64_t oldval,
 +	int64_t newval, ...)
  {
 -	return atomic_cas_64(addr, oldval, newval) == oldval;
 +	const uin64_t oldv = (uint64_t)oldval;
 +	const uin64_t newv = (uint64_t)newval;
 +
 +	return atomic_cas_64((volatile uint64 *)addr, oldv, newv) == oldv;
  }
  
  #endif
 Index: atomic_cas_8_cas.c
 ===================================================================
 RCS file: /cvsroot/src/common/lib/libc/atomic/atomic_cas_8_cas.c,v
 retrieving revision 1.3
 diff -u -p -r1.3 atomic_cas_8_cas.c
 --- atomic_cas_8_cas.c	21 Feb 2014 16:06:48 -0000	1.3
 +++ atomic_cas_8_cas.c	19 Mar 2026 19:44:18 -0000
 @@ -35,13 +35,17 @@
  #include <stdbool.h>
  #endif
  #include <sys/atomic.h>
 +#include <stdarg.h>
  
 -bool bool_compare_and_swap_1(volatile uint8_t *, uint8_t, uint8_t, ...)
 +bool bool_compare_and_swap_1(volatile int8_t *, int8_t, int8_t, ...)
      asm("__sync_bool_compare_and_swap_1");
  
  bool
 -bool_compare_and_swap_1(volatile uint8_t *addr, uint8_t oldval,
 -	uint8_t newval, ...)
 +bool_compare_and_swap_1(volatile int8_t *addr, int8_t oldval,
 +	int8_t newval, ...)
  {
 -	return atomic_cas_8(addr, oldval, newval) == oldval;
 +	uint8_t oldv = (uint8_t)oldval;
 +	uint8_t newv = (uint8_t)newval;
 +
 +	return atomic_cas_8((volatile uint8_t *)addr, oldv, newv) == oldv;
  }
 Index: atomic_cas_by_cas32.c
 ===================================================================
 RCS file: /cvsroot/src/common/lib/libc/atomic/atomic_cas_by_cas32.c,v
 retrieving revision 1.4
 diff -u -p -r1.4 atomic_cas_by_cas32.c
 --- atomic_cas_by_cas32.c	3 Sep 2014 19:30:47 -0000	1.4
 +++ atomic_cas_by_cas32.c	19 Mar 2026 19:44:18 -0000
 @@ -64,8 +64,6 @@ _atomic_cas_16(volatile uint16_t *addr, 
  	return old;
  }
  
 -crt_alias(__sync_val_compare_and_swap_2,_atomic_cas_16)
 -
  uint8_t
  _atomic_cas_8(volatile uint8_t *addr, uint8_t old, uint8_t new)
  {
 @@ -87,5 +85,3 @@ _atomic_cas_8(volatile uint8_t *addr, ui
  
  	return old;
  }
 -
 -crt_alias(__sync_val_compare_and_swap_1,_atomic_cas_8)
 Index: atomic_init_testset.c
 ===================================================================
 RCS file: /cvsroot/src/common/lib/libc/atomic/atomic_init_testset.c,v
 retrieving revision 1.21
 diff -u -p -r1.21 atomic_init_testset.c
 --- atomic_init_testset.c	9 Jan 2026 08:44:57 -0000	1.21
 +++ atomic_init_testset.c	19 Mar 2026 19:44:18 -0000
 @@ -345,8 +345,43 @@ __strong_alias(_atomic_cas_ptr_ni,_atomi
  atomic_op_alias(atomic_cas_64,_atomic_cas_64)
  atomic_op_alias(atomic_cas_64_ni,_atomic_cas_64)
  __strong_alias(_atomic_cas_64_ni,_atomic_cas_64)
 -crt_alias(__sync_val_compare_and_swap_8,_atomic_cas_64)
 +
 +int64_t sync_val_compare_and_swap_8(volatile int64_t *addr, int64_t old, int64_t new)
 +    asm("__sync_val_compare_and_swap_8");
 +
 +int64_t
 +sync_val_compare_and_swap_8(volatile int64_t *addr, int64_t old, int64_t new)
 +{
 +	const uint64_t oldv = (uint64_t)old;
 +	const uint64_t newv = (uint64_t)new;
 +
 +	return _atomic_cas_64((volatile uint64_t *)addr, oldv, newv);
 +}
 +
  #endif
  crt_alias(__sync_val_compare_and_swap_4,_atomic_cas_32)
 -crt_alias(__sync_val_compare_and_swap_2,_atomic_cas_16)
 -crt_alias(__sync_val_compare_and_swap_1,_atomic_cas_8)
 +
 +
 +int16_t sync_val_compare_and_swap_2(volatile int16_t *addr, int16_t old, int16_t new)
 +    asm("__sync_val_compare_and_swap_2");
 +
 +int16_t
 +sync_val_compare_and_swap_2(volatile int16_t *addr, int16_t old, int16_t new)
 +{
 +	const uint16_t oldv = (uint16_t)old;
 +	const uint16_t newv = (uint16_t)new;
 +
 +	return _atomic_cas_16((volatile uint16_t *)addr, oldv, newv);
 +}
 +
 +int8_t sync_val_compare_and_swap_1(volatile int8_t *addr, int8_t old, int8_t new)
 +    asm("__sync_val_compare_and_swap_1");
 +
 +int8_t
 +sync_val_compare_and_swap_1(volatile int8_t *addr, int8_t old, int8_t new)
 +{
 +	const uint8_t oldv = (uint8_t)old;
 +	const uint8_t newv = (uint8_t)new;
 +
 +	return _atomic_cas_8((volatile uint8_t *)addr, oldv, newv);
 +}