ports/sysdeps/arm/sysdep.h

   1 /* Assembler macros for ARM.
   2    Copyright (C) 1997-2013 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library.  If not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <sysdeps/generic/sysdep.h>
  20 #include <features.h>
  21
  22 #if (!defined (__ARM_ARCH_2__) && !defined (__ARM_ARCH_3__) \
  23      && !defined (__ARM_ARCH_3M__) && !defined (__ARM_ARCH_4__))
  24 # define __USE_BX__
  25 #endif
  26
  27 #ifdef  __ASSEMBLER__
  28
  29 /* Syntactic details of assembler.  */
  30
  31 #define ALIGNARG(log2) log2
  32 #define ASM_SIZE_DIRECTIVE(name) .size name,.-name
  33
  34 #define PLTJMP(_x)      _x##(PLT)
  35
  36 /* APCS-32 doesn't preserve the condition codes across function call. */
  37 #ifdef __APCS_32__
  38 #define LOADREGS(cond, base, reglist...)\
  39         ldm##cond       base,reglist
  40 #ifdef __USE_BX__
  41 #define RETINSTR(cond, reg)     \
  42         bx##cond        reg
  43 #define DO_RET(_reg)            \
  44         bx _reg
  45 #else
  46 #define RETINSTR(cond, reg)     \
  47         mov##cond       pc, reg
  48 #define DO_RET(_reg)            \
  49         mov pc, _reg
  50 #endif
  51 #else  /* APCS-26 */
  52 #define LOADREGS(cond, base, reglist...)\
  53         ldm##cond       base,reglist^
  54 #define RETINSTR(cond, reg)     \
  55         mov##cond##s    pc, reg
  56 #define DO_RET(_reg)            \
  57         movs pc, _reg
  58 #endif
  59
  60 /* Define an entry point visible from C.  */
  61 #define ENTRY(name)                                     \
  62         .globl  C_SYMBOL_NAME(name);                    \
  63         .type   C_SYMBOL_NAME(name),%function;          \
  64         .align  ALIGNARG(4);                            \
  65   C_LABEL(name)                                         \
  66         CFI_SECTIONS;                                   \
  67         cfi_startproc;                                  \
  68         CALL_MCOUNT
  69
  70 #define CFI_SECTIONS                                    \
  71         .cfi_sections .debug_frame
  72
  73 #undef  END
  74 #define END(name)                                       \
  75         cfi_endproc;                                    \
  76         ASM_SIZE_DIRECTIVE(name)
  77
  78 /* If compiled for profiling, call `mcount' at the start of each function.  */
  79 #ifdef  PROF
  80 /* Call __gnu_mcount_nc if GCC >= 4.4.  */
  81 #if __GNUC_PREREQ(4,4)
  82 #define CALL_MCOUNT                                     \
  83         str     lr,[sp, #-4]!;                          \
  84         cfi_adjust_cfa_offset (4);                      \
  85         cfi_rel_offset (lr, 0);                         \
  86         bl      PLTJMP(mcount);                         \
  87         cfi_adjust_cfa_offset (-4);                     \
  88         cfi_restore (lr)
  89 #else /* else call _mcount */
  90 #define CALL_MCOUNT                                     \
  91         str     lr,[sp, #-4]!;                          \
  92         cfi_adjust_cfa_offset (4);                      \
  93         cfi_rel_offset (lr, 0);                         \
  94         bl      PLTJMP(mcount);                         \
  95         ldr     lr, [sp], #4;                           \
  96         cfi_adjust_cfa_offset (-4);                     \
  97         cfi_restore (lr)
  98 #endif
  99 #else
 100 #define CALL_MCOUNT             /* Do nothing.  */
 101 #endif
 102
 103 /* Since C identifiers are not normally prefixed with an underscore
 104    on this system, the asm identifier `syscall_error' intrudes on the
 105    C name space.  Make sure we use an innocuous name.  */
 106 #define syscall_error   __syscall_error
 107 #if __GNUC_PREREQ(4,4)
 108 #define mcount          __gnu_mcount_nc
 109 #else
 110 #define mcount          _mcount
 111 #endif
 112
 113 /* Tag_ABI_align8_preserved: This code preserves 8-byte
 114    alignment in any callee.  */
 115         .eabi_attribute 25, 1
 116 /* Tag_ABI_align8_needed: This code may require 8-byte alignment from
 117    the caller.  */
 118         .eabi_attribute 24, 1
 119
 120 /* The thumb2 encoding is reasonably complete.  Unless suppressed, use it.  */
 121         .syntax unified
 122 # if defined(__thumb2__) && !defined(NO_THUMB)
 123         .thumb
 124 #else
 125 #  undef __thumb__
 126 #  undef __thumb2__
 127         .arm
 128 # endif
 129
 130 /* Load or store to/from a pc-relative EXPR into/from R, using T.  */
 131 # ifdef __thumb2__
 132 #  define LDST_PCREL(OP, R, T, EXPR) \
 133         ldr     T, 98f;                                 \
 134         .subsection 2;                                  \
 135 98:     .word   EXPR - 99f - PC_OFS;                    \
 136         .previous;                                      \
 137 99:     add     T, T, pc;                               \
 138         OP      R, [T]
 139 # else
 140 #  define LDST_PCREL(OP, R, T, EXPR) \
 141         ldr     T, 98f;                                 \
 142         .subsection 2;                                  \
 143 98:     .word   EXPR - 99f - PC_OFS;                    \
 144         .previous;                                      \
 145 99:     OP      R, [pc, T]
 146 # endif
 147
 148 /* Cope with negative memory offsets, which thumb can't encode.
 149    Use NEGOFF_ADJ_BASE to (conditionally) alter the base register,
 150    and then NEGOFF_OFF1 to use 0 for thumb and the offset for arm,
 151    or NEGOFF_OFF2 to use A-B for thumb and A for arm.  */
 152 # ifdef __thumb2__
 153 #  define NEGOFF_ADJ_BASE(R, OFF)       add R, R, $OFF
 154 #  define NEGOFF_ADJ_BASE2(D, S, OFF)   add D, S, $OFF
 155 #  define NEGOFF_OFF1(R, OFF)           [R]
 156 #  define NEGOFF_OFF2(R, OFFA, OFFB)    [R, $((OFFA) - (OFFB))]
 157 # else
 158 #  define NEGOFF_ADJ_BASE(R, OFF)
 159 #  define NEGOFF_ADJ_BASE2(D, S, OFF)   mov D, S
 160 #  define NEGOFF_OFF1(R, OFF)           [R, $OFF]
 161 #  define NEGOFF_OFF2(R, OFFA, OFFB)    [R, $OFFA]
 162 # endif
 163
 164 /* Helper to get the TLS base pointer.  The interface is that TMP is a
 165    register that may be used to hold the LR, if necessary.  TMP may be
 166    LR itself to indicate that LR need not be saved.  The base pointer
 167    is returned in R0.  Only R0 and TMP are modified.
 168
 169    At this generic level we have no tricks to pull.  Call the ABI routine.  */
 170 # define GET_TLS(TMP)                                   \
 171         push    { r1, r2, r3, lr };                     \
 172         cfi_remember_state;                             \
 173         cfi_adjust_cfa_offset (16);                     \
 174         cfi_rel_offset (r1, 0);                         \
 175         cfi_rel_offset (r2, 4);                         \
 176         cfi_rel_offset (r3, 8);                         \
 177         cfi_rel_offset (lr, 12);                        \
 178         bl      __aeabi_read_tp;                        \
 179         pop     { r1, r2, r3, lr };                     \
 180         cfi_restore_state
 181
 182 #endif  /* __ASSEMBLER__ */
 183
 184 /* This number is the offset from the pc at the current location.  */
 185 #ifdef __thumb__
 186 # define PC_OFS  4
 187 #else
 188 # define PC_OFS  8
 189 #endif