glibc/ports/sysdeps/arm/sysdep.h

/* Assembler macros for ARM.
   Copyright (C) 1997-2013 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library.  If not, see
   <http://www.gnu.org/licenses/>.  */

#include <sysdeps/generic/sysdep.h>
#include <features.h>

#if (!defined (__ARM_ARCH_2__) && !defined (__ARM_ARCH_3__) \
     && !defined (__ARM_ARCH_3M__) && !defined (__ARM_ARCH_4__))
# define __USE_BX__
#endif

#ifdef	__ASSEMBLER__

/* Syntactic details of assembler.  */

#define ALIGNARG(log2) log2
#define ASM_SIZE_DIRECTIVE(name) .size name,.-name

#define PLTJMP(_x)	_x##(PLT)

/* APCS-32 doesn't preserve the condition codes across function call. */
#ifdef __APCS_32__
#define LOADREGS(cond, base, reglist...)\
	ldm##cond	base,reglist
#ifdef __USE_BX__
#define RETINSTR(cond, reg)	\
	bx##cond	reg
#define DO_RET(_reg)		\
	bx _reg
#else
#define RETINSTR(cond, reg)	\
	mov##cond	pc, reg
#define DO_RET(_reg)		\
	mov pc, _reg
#endif
#else  /* APCS-26 */
#define LOADREGS(cond, base, reglist...)\
	ldm##cond	base,reglist^
#define RETINSTR(cond, reg)	\
	mov##cond##s	pc, reg
#define DO_RET(_reg)		\
	movs pc, _reg
#endif

/* Define an entry point visible from C.  */
#define	ENTRY(name)					\
	.globl	C_SYMBOL_NAME(name);			\
	.type	C_SYMBOL_NAME(name),%function;		\
	.align	ALIGNARG(4);				\
  C_LABEL(name)						\
	CFI_SECTIONS;					\
	cfi_startproc;					\
	CALL_MCOUNT

#define CFI_SECTIONS					\
	.cfi_sections .debug_frame

#undef	END
#define END(name)					\
	cfi_endproc;					\
	ASM_SIZE_DIRECTIVE(name)

/* If compiled for profiling, call `mcount' at the start of each function.  */
#ifdef	PROF
/* Call __gnu_mcount_nc if GCC >= 4.4.  */
#if __GNUC_PREREQ(4,4)
#define CALL_MCOUNT					\
	str	lr,[sp, #-4]!;				\
	cfi_adjust_cfa_offset (4);			\
	cfi_rel_offset (lr, 0);				\
	bl	PLTJMP(mcount);				\
	cfi_adjust_cfa_offset (-4);			\
	cfi_restore (lr)
#else /* else call _mcount */
#define CALL_MCOUNT					\
	str	lr,[sp, #-4]!;				\
	cfi_adjust_cfa_offset (4);			\
	cfi_rel_offset (lr, 0);				\
	bl	PLTJMP(mcount);				\
	ldr	lr, [sp], #4;				\
	cfi_adjust_cfa_offset (-4);			\
	cfi_restore (lr)
#endif
#else
#define CALL_MCOUNT		/* Do nothing.  */
#endif

/* Since C identifiers are not normally prefixed with an underscore
   on this system, the asm identifier `syscall_error' intrudes on the
   C name space.  Make sure we use an innocuous name.  */
#define	syscall_error	__syscall_error
#if __GNUC_PREREQ(4,4)
#define mcount		__gnu_mcount_nc
#else
#define mcount		_mcount
#endif

/* Tag_ABI_align8_preserved: This code preserves 8-byte
   alignment in any callee.  */
	.eabi_attribute 25, 1
/* Tag_ABI_align8_needed: This code may require 8-byte alignment from
   the caller.  */
	.eabi_attribute 24, 1

/* Load or store to/from a pc-relative EXPR into/from R, using T.  */
# ifdef __thumb2__
#  define LDST_PCREL(OP, R, T, EXPR) \
	ldr	T, 98f;					\
	.subsection 2;					\
98:	.word	EXPR - 99f - PC_OFS;			\
	.previous;					\
99:	add	T, T, pc;				\
	OP	R, [T]
# else
#  define LDST_PCREL(OP, R, T, EXPR) \
	ldr	T, 98f;					\
	.subsection 2;					\
98:	.word	EXPR - 99f - PC_OFS;			\
	.previous;					\
99:	OP	R, [pc, T]
# endif
#endif	/* __ASSEMBLER__ */

/* This number is the offset from the pc at the current location.  */
/* ??? At the moment we're not turning on thumb mode in assembly.  */
#if defined(__thumb__) && !defined(__ASSEMBLER__)
# define PC_OFS  4
#else
# define PC_OFS  8
#endif