Re: toolchain/51121: sparc64 can't build perl

[Martin Husemann <martin%duskware.de@localhost>]

The following reply was made to PR toolchain/51121; it has been noted by GNATS.

From: Martin Husemann <martin%duskware.de@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: toolchain/51121: sparc64  can't build perl
Date: Wed, 11 May 2016 11:06:03 +0200

 Suggested by Andrew Pinski in
 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71051
 
 I reworked the crt source slightly and it now works even if compiled wiht -O2
 for me.
 
 Suggestions for a better name for the macro hiding the asm() ?
 Should we put that somewhere else, in case we need to reuse it elsewhere?
 (Linksets?)
 
 Joerg, how does this interact with Clang?
 
 Martin
 
 Index: common/Makefile.inc
 ===================================================================
 RCS file: /cvsroot/src/lib/csu/common/Makefile.inc,v
 retrieving revision 1.31
 diff -u -p -r1.31 Makefile.inc
 --- common/Makefile.inc	10 May 2016 10:23:09 -0000	1.31
 +++ common/Makefile.inc	11 May 2016 08:43:43 -0000
 @@ -17,14 +17,6 @@ OBJS+=		sysident.o
  .if ${MKPIC} == "yes"
  OBJS+=		crtbeginS.o
  CFLAGS.crtbegin.c+= -fPIE
 -# XXXGCC5 - GCC 5 miscompiles crtbeginS.c on many platforms.  on SPARC it
 -# XXXGCC5   emits "clr %g1; call %g1", which is effectively jumping to zero.
 -. if defined(HAVE_GCC) && ${HAVE_GCC} == 53 && \
 -     !exists(${ARCHDIR}/crtbegin.S)
 -CFLAGS.crt0-common.c+=	-O1
 -CFLAGS.crtbeginS.c+=	-O1
 -CFLAGS.crtbegin.c+=	-O1
 -. endif
  .endif
  
  .if ${MACHINE_ARCH} == "alpha"
 Index: common/crt0-common.c
 ===================================================================
 RCS file: /cvsroot/src/lib/csu/common/crt0-common.c,v
 retrieving revision 1.13
 diff -u -p -r1.13 crt0-common.c
 --- common/crt0-common.c	31 Jan 2013 22:24:25 -0000	1.13
 +++ common/crt0-common.c	11 May 2016 08:43:43 -0000
 @@ -89,6 +89,13 @@ do {						\
  
  #ifdef HAVE_INITFINI_ARRAY
  /*
 + * Make sure the compiler does not know about start/end pointing
 + * to different arrays (so pointer comparison is undefined
 + * behaviour).
 + */
 +#define UNALIAS_PTR(PTR)	asm("":"+r"(PTR))
 +
 +/*
   * If we are using INIT_ARRAY/FINI_ARRAY and we are linked statically,
   * we have to process these instead of relying on RTLD to do it for us.
   *
 @@ -111,7 +118,12 @@ __weakref_visible const fptr_t fini_arra
  static inline void
  _preinit(void)
  {
 -	for (const fptr_t *f = preinit_array_start; f < preinit_array_end; f++) {
 +	const fptr_t *start = preinit_array_start;
 +	const fptr_t *end = preinit_array_end;
 +	UNALIAS_PTR(start);
 +	UNALIAS_PTR(end);
 +
 +	for (const fptr_t *f = start; f < end; f++) {
  		(*f)();
  	}
  }
 @@ -119,7 +131,12 @@ _preinit(void)
  static inline void
  _init(void)
  {
 -	for (const fptr_t *f = init_array_start; f < init_array_end; f++) {
 +	const fptr_t *start = init_array_start;
 +	const fptr_t *end = init_array_end;
 +	UNALIAS_PTR(start);
 +	UNALIAS_PTR(end);
 +
 +	for (const fptr_t *f = start; f < end; f++) {
  		(*f)();
  	}
  }
 @@ -127,7 +144,12 @@ _init(void)
  static void
  _fini(void)
  {
 -	for (const fptr_t *f = fini_array_start; f < fini_array_end; f++) {
 +	const fptr_t *start = fini_array_start;
 +	const fptr_t *end = fini_array_end;
 +	UNALIAS_PTR(start);
 +	UNALIAS_PTR(end);
 +
 +	for (const fptr_t *f = start; f < end; f++) {
  		(*f)();
  	}
  }
 Index: common/crtbegin.c
 ===================================================================
 RCS file: /cvsroot/src/lib/csu/common/crtbegin.c,v
 retrieving revision 1.9
 diff -u -p -r1.9 crtbegin.c
 --- common/crtbegin.c	6 May 2014 16:02:10 -0000	1.9
 +++ common/crtbegin.c	11 May 2016 08:43:43 -0000
 @@ -90,7 +90,20 @@ __do_global_ctors_aux(void)
  		Jv_RegisterClasses(__JCR_LIST__);
  
  #if !defined(HAVE_INITFINI_ARRAY)
 -	for (const fptr_t *p = __CTOR_LIST_END__; p > __CTOR_LIST__ + 1; ) {
 +
 +/*
 + * Make sure the compiler does not know about start/end pointing
 + * to different arrays (so pointer comparison is undefined
 + * behaviour).
 + */
 +#define UNALIAS_PTR(PTR)	asm("":"+r"(PTR))
 +
 +	const fptr_t *start = __CTOR_LIST__;
 +	const fptr_t *end = __CTOR_LIST_END__;
 +	UNALIAS_PTR(start);
 +	UNALIAS_PTR(end);
 +
 +	for (const fptr_t *p = end; p > start + 1; ) {
  		(*(*--p))();
  	}
  #endif
 @@ -122,7 +135,12 @@ __do_global_dtors_aux(void)
  #endif
  
  #if !defined(HAVE_INITFINI_ARRAY)
 -	for (const fptr_t *p = __DTOR_LIST__ + 1; p < __DTOR_LIST_END__; ) {
 +	const fptr_t *start = __DTOR_LIST__;
 +	const fptr_t *end = __DTOR_LIST_END__;
 +	UNALIAS_PTR(start);
 +	UNALIAS_PTR(end);
 +
 +	for (const fptr_t *p = start + 1; p < end; ) {
  		(*(*p++))();
  	}
  #endif