path: root/orc/orcarm.c

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include <sys/types.h>

#include <orc/orcdebug.h>
#include <orc/orcprogram.h>
#include <orc/orcarm.h>
#include <orc/orcutils.h>

#if defined(HAVE_ARM) || defined(HAVE_AARCH64)
#if defined(__APPLE__)
#include  <libkern/OSCacheControl.h>
#endif
#if defined (_WIN32)
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#endif
#endif

/**
 * SECTION:orcarm
 * @title: ARM
 * @short_description: code generation for ARM
 */

const char *
orc_arm_cond_name (OrcArmCond cond)
{
  static const char *cond_names[] = {
    "eq", "ne", "cs", "cc", "mi", "pl", "vs", "vc",
    "hi", "ls", "ge", "lt", "gt", "le", "", ""
  };
  if ((int)cond < 0 || (int)cond >= 16) {
    return "ERROR";
  }
  return cond_names[cond&0xf];
}

const char *
orc_arm_reg_name (int reg)
{
#if 0
  static const char *gp_regs[] = {
    "a1", "a2", "a3", "a4",
    "v1", "v2", "v3", "v4",
    "v5", "v6", "v7", "v8",
    "ip", "sp", "lr", "pc" };
#else
  static const char *gp_regs[] = {
    "r0", "r1", "r2", "r3",
    "r4", "r5", "r6", "r7",
    "r8", "r9", "r10", "r11",
    "ip", "sp", "lr", "pc" };
  /* "r12", "r13", "r14", "r15" }; */
#endif

  if (reg < ORC_GP_REG_BASE || reg >= ORC_GP_REG_BASE+16) {
    return "ERROR";
  }

  return gp_regs[reg&0xf];
}

const char *
orc_arm64_reg_name (int reg, OrcArm64RegBits bits)
{
  static const char *gp_regs64[] = {
     "x0",  "x1",  "x2",  "x3",  "x4",  "x5",  "x6",  "x7",  "x8",  "x9",
    "x10", "x11", "x12", "x13", "x14", "x15", "x16", "x17", "x18", "x19",
    "x20", "x21", "x22", "x23", "x24", "x25", "x26", "x27", "x28", "x29",
    "x30",  "sp"
  };
  static const char *gp_regs32[] = {
     "w0",  "w1",  "w2",  "w3",  "w4",  "w5",  "w6",  "w7",  "w8",  "w9",
    "w10", "w11", "w12", "w13", "w14", "w15", "w16", "w17", "w18", "w19",
    "w20", "w21", "w22", "w23", "w24", "w25", "w26", "w27", "w28", "w29",
    "w30",  "sp"
  };

  if (reg < ORC_GP_REG_BASE || reg >= ORC_GP_REG_BASE+32) {
    return "ERROR";
  }

  return bits == ORC_ARM64_REG_64 ? gp_regs64[reg&0x1f] : gp_regs32[reg&0x1f];
}

void
orc_arm_emit (OrcCompiler *compiler, orc_uint32 insn)
{
  ORC_WRITE_UINT32_LE (compiler->codeptr, insn);
  compiler->codeptr+=4;
}

void
orc_arm_emit_bx_lr (OrcCompiler *compiler)
{
  if (compiler->is_64bit) {
    orc_arm64_emit_ret (compiler, ORC_ARM64_LR);
  } else {
    ORC_ASM_CODE(compiler,"  bx lr\n");
    orc_arm_emit (compiler, 0xe12fff1e);
  }
}

static int
count_reg_ones (int regs)
{
  int count = 0;

  while (regs) {
    count += regs & 1;
    regs >>= 1;
  }

  return count;
}

void
orc_arm_emit_push (OrcCompiler *compiler, int regs, orc_uint32 vregs)
{
  int i;

  if (regs) {
    int x = 0;

    if (compiler->is_64bit) {
      int count, stores;
      int stack_increased = 0;
      /** a number of 1s in regs */
      count = count_reg_ones (regs);
      /** AArch64 requires a 16-byte aligned stack pointer */
      stores = (count-1)/2+1;
      x = -1;
      for(i=0;i<32;i++){
        if (stores == 0) break;
        if (regs & (1<<i)) {
          if (stack_increased == 0) {
            /** increase stack area & store registers */
            if (count % 2 == 1) {
              orc_arm64_emit_store_pre (compiler, 64, ORC_GP_REG_BASE+i,
                  ORC_ARM64_SP, (stores--) * -16);
              stack_increased = 1;
              continue;
            } else if (x != -1) {
              orc_arm64_emit_store_pair_pre (compiler, 64, ORC_GP_REG_BASE+x,
                  ORC_GP_REG_BASE+i, ORC_ARM64_SP, (stores--) * -16);
              stack_increased = 1;
              x = -1;
              continue;
            }
          }

          if (x != -1) {
            /** store registers */
            orc_arm64_emit_store_pair_reg (compiler, 64, ORC_GP_REG_BASE+x,
                ORC_GP_REG_BASE+i, ORC_ARM64_SP, (stores--) * 16);
            x = -1;
          } else {
            x = i;
          }
        }
      }
    } else {
      ORC_ASM_CODE(compiler,"  push {");
      for(i=0;i<16;i++){
        if (regs & (1<<i)) {
          x |= (1<<i);
          ORC_ASM_CODE(compiler,"r%d", i);
          if (x != regs) {
            ORC_ASM_CODE(compiler,", ");
          }
        }
      }
      ORC_ASM_CODE(compiler,"}\n");

      orc_arm_emit (compiler, 0xe92d0000 | regs);
    }
  }

  if (vregs) {
    int first = -1, last = -1, nregs;

    ORC_ASM_CODE(compiler, "  vpush {");
    for(i=0; i<32; ++i) {
      if (vregs & (1U << i)) {
        if (first==-1) {
           ORC_ASM_CODE(compiler, "d%d", i);
           first = i;
        }
        last = i;
      }
    }
    /* What's the deal with even/odd registers ? */
    ORC_ASM_CODE(compiler, "-d%d}\n", last+1);

    nregs = last + 1 - first + 1;
    orc_arm_emit (compiler, 0xed2d0b00 | (((first & 0x10) >> 4) << 22) | ((first & 0x0f) << 12) | (nregs << 1));
  }
}

void
orc_arm_emit_pop (OrcCompiler *compiler, int regs, orc_uint32 vregs)
{
  int i;


  if (vregs) {
    int first = -1, last = -1, nregs;

    ORC_ASM_CODE(compiler, "  vpop {");
    for(i=0; i<32; ++i) {
      if (vregs & (1U << i)) {
        if (first==-1) {
           ORC_ASM_CODE(compiler, "d%d", i);
           first = i;
        }
        last = i;
      }
    }
    ORC_ASM_CODE(compiler, "-d%d}\n", last+1);

    nregs = last + 1 - first + 1;
    orc_arm_emit (compiler, 0xecbd0b00 | (((first & 0x10) >> 4) << 22) | ((first & 0x0f) << 12) | (nregs << 1));
  }

  if (regs) {
    int x = 0;

    if (compiler->is_64bit) {
      int count, loads, tmp_loads;
      /** a number of 1s in regs */
      count = count_reg_ones (regs);
      /** AArch64 requires a 16-byte aligned stack pointer */
      loads = (count-1)/2+1;
      tmp_loads = loads;
      x = -1;
      for(i=31;i>=0;i--){
        if (regs & (1<<i)) {
          if (x != -1) {
            if (tmp_loads == 1) break;
            /** load registers */
            orc_arm64_emit_load_pair_reg (compiler, 64, ORC_GP_REG_BASE+i,
                ORC_GP_REG_BASE+x, ORC_ARM64_SP, (loads - (--tmp_loads)) * 16);
            x = -1;
          } else {
            x = i;
          }
        }
      }
      /** decrease stack area & load registers */
      if (count % 2 == 1) {
        orc_arm64_emit_load_post (compiler, 64, ORC_GP_REG_BASE+x,
            ORC_ARM64_SP, loads * 16);
      } else {
        orc_arm64_emit_load_pair_post (compiler, 64, ORC_GP_REG_BASE+i,
            ORC_GP_REG_BASE+x, ORC_ARM64_SP, loads * 16);
      }
    } else {
      ORC_ASM_CODE(compiler,"  pop {");
      for(i=0;i<16;i++){
        if (regs & (1<<i)) {
          x |= (1<<i);
          ORC_ASM_CODE(compiler,"r%d", i);
          if (x != regs) {
            ORC_ASM_CODE(compiler,", ");
          }
        }
      }
      ORC_ASM_CODE(compiler,"}\n");

      orc_arm_emit (compiler, 0xe8bd0000 | regs);
    }
  }
}

void
orc_arm_emit_label (OrcCompiler *compiler, int label)
{
  ORC_ASSERT (label < ORC_N_LABELS);

  ORC_ASM_CODE(compiler,".L%d:\n", label);

  compiler->labels[label] = compiler->codeptr;
}

void
orc_arm_add_fixup (OrcCompiler *compiler, int label, int type)
{
  ORC_ASSERT (compiler->n_fixups < ORC_N_FIXUPS);

  compiler->fixups[compiler->n_fixups].ptr = compiler->codeptr;
  compiler->fixups[compiler->n_fixups].label = label;
  compiler->fixups[compiler->n_fixups].type = type;
  compiler->n_fixups++;
}

void
orc_arm_do_fixups (OrcCompiler *compiler)
{
  int i;
  for(i=0;i<compiler->n_fixups;i++){
    unsigned char *label = compiler->labels[compiler->fixups[i].label];
    unsigned char *ptr = compiler->fixups[i].ptr;
    orc_uint32 code;
    int diff;

    if (compiler->fixups[i].type == 0) {
      code = ORC_READ_UINT32_LE (ptr);
      diff = code;
      if (compiler->is_64bit) {
        diff = ((label - ptr) >> 2);   /** time 4 */
        if (diff != (diff << 6)>>6) {
          ORC_COMPILER_ERROR(compiler, "fixup out of range");
        }
        /** check whether it's conditional or unconditioanl */
        if ((code >> 30) & 1) {
          diff <<= 5;     /** for cond */
          ORC_WRITE_UINT32_LE(ptr, (code&0xff00001f) | (diff&0x00ffffe0));
        } else {
          ORC_WRITE_UINT32_LE(ptr, (code&0xfc000000) | (diff&0x03ffffff));
        }
      } else {
        diff = (diff << 8) >> 8;
        diff += ((label - ptr) >> 2);
        if (diff != (diff << 8)>>8) {
          ORC_COMPILER_ERROR(compiler, "fixup out of range");
        }
        ORC_WRITE_UINT32_LE(ptr, (code&0xff000000) | (diff&0x00ffffff));
      }
    } else {
      code = ORC_READ_UINT32_LE (ptr);
      diff = code;
      /* We store the offset in the code as signed, but the CPU considers
       * it unsigned */
      diff = (diff << 24) >> 24;
      diff += ((label - ptr) >> 2);
      if (diff != (diff & 0xff)) {
        ORC_COMPILER_ERROR(compiler, "fixup out of range (%d > 255)", diff);
      }
      ORC_WRITE_UINT32_LE(ptr, (code&0xffffff00) | (diff&0x000000ff));
    }
  }
}

void
orc_arm_emit_align (OrcCompiler *compiler, int align_shift)
{
  int diff;

  diff = (compiler->code - compiler->codeptr)&((1<<align_shift) - 1);
  while (diff) {
    orc_arm_emit_nop (compiler);
    diff-=4;
  }
}

void
orc_arm_emit_nop (OrcCompiler *compiler)
{
  ORC_ASM_CODE(compiler,"  nop\n");
  if (compiler->is_64bit)
    orc_arm_emit (compiler, 0xd503201f);
  else
    orc_arm_emit (compiler, 0xe1a00000);
}

void
orc_arm_emit_branch (OrcCompiler *compiler, int cond, int label)
{
  orc_uint32 code;

  if (compiler->is_64bit) {
    /** B.cond
     *    3                   2                   1
     *  1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
     * +---------------------------------------------------------------+
     * |0 1 0 1 0 1 0|0|                imm19                |0| cond  |
     * +---------------------------------------------------------------+
     *
     *  B
     *    3                   2                   1
     *  1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
     * +---------------------------------------------------------------+
     * |0 0 0 1 0 1|                       imm26                       |
     * +---------------------------------------------------------------+
     *
     * Note that we don't know exact imm19/imm26 yet, so need fixup codes.
     */
    if (cond < ORC_ARM_COND_AL) {
      code = 0x54000000;
      code |=  cond&0xf;

      ORC_ASM_CODE(compiler,"  b.%s .L%d\n", orc_arm_cond_name(cond), label);
    } else {
      code = 0x14000000;

      ORC_ASM_CODE(compiler,"  b .L%d\n", label);
    }
  } else {
    code = 0x0afffffe;
    code |= (cond&0xf) << 28;

    ORC_ASM_CODE(compiler,"  b%s .L%d\n", orc_arm_cond_name(cond), label);
  }
  orc_arm_add_fixup (compiler, label, 0);
  orc_arm_emit (compiler, code);
}

void
orc_arm_emit_load_imm (OrcCompiler *compiler, int dest, int imm)
{
  orc_uint32 code;
  int shift2;
  unsigned int x;

  if ((imm & 0xff) == imm) {
    shift2 = 0;
    x = imm;
  } else {
    shift2 = 0;
    x = imm & 0xffffffff;
    while ((x & 3) == 0) {
      x >>= 2;
      shift2++;
    }
    if (x > 0xff) {
      ORC_PROGRAM_ERROR(compiler, "bad immediate value");
    }
  }

  code = 0xe3a00000;
  code |= (dest&0xf) << 12;
  code |= (((16-shift2)&0xf) << 8);
  code |= (x&0xff);

  ORC_ASM_CODE(compiler,"  mov %s, #0x%08x\n", orc_arm_reg_name (dest), imm);
  orc_arm_emit (compiler, code);
}

void
orc_arm_emit_add_imm (OrcCompiler *compiler, int dest, int src1, int imm)
{
  orc_uint32 code;
  int shift2;
  unsigned int x;

  if ((imm & 0xff) == imm) {
    shift2 = 0;
    x = imm;
  } else {
    shift2 = 0;
    x = imm & 0xffffffff;
    while ((x & 3) == 0) {
      x >>= 2;
      shift2++;
    }
    if (x > 0xff) {
      ORC_PROGRAM_ERROR(compiler, "bad immediate value");
    }
  }

  code = 0xe2800000;
  code |= (src1&0xf) << 16;
  code |= (dest&0xf) << 12;
  code |= (((16-shift2)&0xf) << 8);
  code |= (x&0xff);

  ORC_ASM_CODE(compiler,"  add %s, %s, #0x%08x\n", orc_arm_reg_name (dest),
      orc_arm_reg_name(src1), imm);
  orc_arm_emit (compiler, code);
}

void
orc_arm_emit_and_imm (OrcCompiler *compiler, int dest, int src1, int value)
{
  orc_uint32 code;

  code = 0xe2000000;
  code |= (src1&0xf) << 16;
  code |= (dest&0xf) << 12;
  code |= (value) << 0;

  ORC_ASM_CODE(compiler,"  and %s, %s, #%d\n",
      orc_arm_reg_name (dest),
      orc_arm_reg_name (src1),
      value);
  orc_arm_emit (compiler, code);
}

void
orc_arm_emit_cmp (OrcCompiler *compiler, int src1, int src2)
{
  orc_uint32 code;

  code = 0xe1500000;
  code |= (src1&0xf) << 16;
  code |= (src2&0xf) << 0;

  ORC_ASM_CODE(compiler,"  cmp %s, %s\n",
      orc_arm_reg_name (src1),
      orc_arm_reg_name (src2));
  orc_arm_emit (compiler, code);
}

void
orc_arm_emit_asr_imm (OrcCompiler *compiler, int dest, int src1, int value)
{
  orc_uint32 code;

  if (value == 0) {
    ORC_ERROR("bad immediate value");
  }
  code = 0xe1a00040;
  code |= (src1&0xf) << 0;
  code |= (dest&0xf) << 12;
  code |= (value) << 7;

  ORC_ASM_CODE(compiler,"  asr %s, %s, #%d\n",
      orc_arm_reg_name (dest),
      orc_arm_reg_name (src1),
      value);
  orc_arm_emit (compiler, code);
}

void
orc_arm_emit_lsl_imm (OrcCompiler *compiler, int dest, int src1, int value)
{
  orc_uint32 code;

  if (value == 0) {
    ORC_ERROR("bad immediate value");
  }
  code = 0xe1a00000;
  code |= (src1&0xf) << 0;
  code |= (dest&0xf) << 12;
  code |= (value) << 7;

  ORC_ASM_CODE(compiler,"  lsl %s, %s, #%d\n",
      orc_arm_reg_name (dest),
      orc_arm_reg_name (src1),
      value);
  orc_arm_emit (compiler, code);
}

void
orc_arm_emit_load_reg (OrcCompiler *compiler, int dest, int src1, int offset)
{
  orc_uint32 code;

  code = 0xe5900000;
  code |= (src1&0xf) << 16;
  code |= (dest&0xf) << 12;
  code |= offset&0xfff;

  ORC_ASM_CODE(compiler,"  ldr %s, [%s, #%d]\n",
      orc_arm_reg_name (dest),
      orc_arm_reg_name (src1), offset);
  orc_arm_emit (compiler, code);
}

void
orc_arm_emit_store_reg (OrcCompiler *compiler, int src1, int dest, int offset)
{
  orc_uint32 code;

  code = 0xe5800000;
  code |= (dest&0xf) << 16;
  code |= (src1&0xf) << 12;
  code |= offset&0xfff;

  ORC_ASM_CODE(compiler,"  str %s, [%s, #%d]\n",
      orc_arm_reg_name (src1),
      orc_arm_reg_name (dest), offset);
  orc_arm_emit (compiler, code);
}

void
orc_arm_emit_mov (OrcCompiler *compiler, int dest, int src)
{
  if (dest == src) return;
  orc_arm_emit_mov_r(compiler, ORC_ARM_COND_AL, 0, dest, src);
}

void
orc_arm_emit_sub (OrcCompiler *compiler, int dest, int src1, int src2)
{
  orc_arm_emit_sub_r (compiler, ORC_ARM_COND_AL, 0, dest, src1, src2);
}

void
orc_arm_emit_sub_imm (OrcCompiler *compiler, int dest, int src1, int value,
    int record)
{
  orc_arm_emit_sub_i (compiler, ORC_ARM_COND_AL, record, dest, src1, value);
}

void
orc_arm_emit_add (OrcCompiler *compiler, int dest, int src1, int src2)
{
  orc_arm_emit_add_r (compiler, ORC_ARM_COND_AL, 0, dest, src1, src2);
}

void
orc_arm_emit_cmp_imm (OrcCompiler *compiler, int src1, int value)
{
  orc_arm_emit_cmp_i (compiler, ORC_ARM_COND_AL, src1, value);
}


/* shifter operands */
/*    1
 *  1 0 9 8 7 6 5 4 3 2 1 0
 * +-+-+-+-+-+-+-+-+-+-+-+-+
 * |rotimm |   immed_8     |
 * +-+-+-+-+-+-+-+-+-+-+-+-+
 */
#define arm_so_i(rot,imm) ((((rot)&15)<<8)|((imm)&255))
/*    1
 *  1 0 9 8 7 6 5 4 3 2 1 0
 * +-+-+-+-+-+-+-+-+-+-+-+-+
 * |    Si   | St|0|   Rm  |
 * +-+-+-+-+-+-+-+-+-+-+-+-+
 */
#define arm_so_rsi(Si,St,Rm)   ((((Si)&31)<<7)|(((St)&3)<<5)|((Rm)&15))
#define arm_so_rrx(Rm)         arm_so_rsi(0,ORC_ARM_ROR,Rm)
#define arm_so_r(Rm)           ((Rm)&15)
/*    1
 *  1 0 9 8 7 6 5 4 3 2 1 0
 * +-+-+-+-+-+-+-+-+-+-+-+-+
 * |  Rs   |0| St|1|   Rm  |
 * +-+-+-+-+-+-+-+-+-+-+-+-+
 */
#define arm_so_rsr(Rs,St,Rm)   (0x010|(((Rs)&15)<<8)|(((St)&3)<<5)|((Rm)&15))

/* data processing instructions */
/*    3   2 2 2 2 2     2 2 1     1 1     1   1
 *  1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * | cond  |0 0|I| opcode|S|   Rn  |  Rd   |   shifter_operand     |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 */
#define arm_code_dp(cond,I,opcode,S,Rn,Rd,So) ((((cond)&15)<<28) | (((I)&1)<<25) |   \
                                              (((opcode)&15)<<21) | (((S)&1)<<20) | \
                                              (((Rn)&15)<<16) | (((Rd)&15)<<12) |   \
                                              ((So)&0xfff))

/*
 * type 0:  <op>{<cond>}{s} {<Rd>}, <Rn>, #imm   (imm = (val>>(shift*2))|(val<<(32-(shift*2))))
 * type 1:  <op>{<cond>}{s} {<Rd>}, <Rn>, <Rm>
 * type 2:  <op>{<cond>}{s} {<Rd>}, <Rn>, <Rm>, [LSL|LSR|ASR] #imm
 * type 3:  <op>{<cond>}{s} {<Rd>}, <Rn>, <Rm>, [LSL|LSR|ASR] <Rs>
 * type 4:  <op>{<cond>}{s} {<Rd>,} <Rn>, <Rm>, RRX
 */
void
orc_arm_emit_dp (OrcCompiler *p, int type, OrcArmCond cond, OrcArmDP opcode,
    int S, int Rd, int Rn, int Rm, int shift, orc_uint32 val)
{
  orc_uint32 code;
  int I = 0;
  int shifter_op;
  char shifter[64];
  orc_uint32 imm;
  static const char *shift_names[] = {
    "LSL", "LSR", "ASR", "ROR"
  };
  /* opcodes with Rd */
  static const int op_Rd[] = {
    1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1
  };
  /* opcodes using Rn */
  static const int op_Rn[] = {
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0
  };
  static const char *dp_insn_names[] = {
    "and", "eor", "sub", "rsb", "add", "adc", "sbc", "rsc",
    "tst", "teq", "cmp", "cmn", "orr", "mov", "bic", "mvn"
  };

  switch (type) {
    case 0:
      /* #imm */
      imm = (orc_uint32) val;
      /* if imm <= 0xff we're done. It's recommanded that we choose the
       * smallest shifter value. Impossible values will overflow the shifter. */
      while (imm > 0xff && shift < 16) {
        imm = (imm << 2) | (imm >> 30);
        shift++;
      }
      if (shift > 15) {
        ORC_COMPILER_ERROR(p,"invalid ARM immediate %08x", val);
        return;
      }
      shifter_op = arm_so_i (shift, imm);
      sprintf (shifter, "#0x%08x", val);
      I = 1;
      break;
    case 1:
      /* <Rm> */
      shifter_op = arm_so_r (Rm);
      sprintf (shifter, "%s", orc_arm_reg_name (Rm));
      break;
    case 2:
      /* <Rm>, [LSL|LSR|ASR] #imm */
      shifter_op = arm_so_rsi (val,shift,Rm);
      sprintf (shifter, "%s, %s #%d",
          orc_arm_reg_name (Rm), shift_names[shift], val);
      break;
    case 3:
      /* <Rm>, [LSL|LSR|ASR] <Rs> */
      shifter_op = arm_so_rsr (val,shift,Rm);
      sprintf (shifter, "%s, %s %s",
          orc_arm_reg_name (Rm), shift_names[shift], orc_arm_reg_name (val));
      break;
    case 4:
      /* <Rm>, RRX */
      shifter_op = arm_so_rrx (Rm);
      sprintf (shifter, "%s, RRX",
          orc_arm_reg_name (Rm));
      break;
    default:
      ORC_COMPILER_ERROR(p,"unknown data processing type %d", type);
      return;
  }

  if (op_Rd[opcode]) {
    if (op_Rn[opcode]) {
      /* opcode using Rn */
      code = arm_code_dp (cond, I, opcode, S, Rn, Rd, shifter_op);
      ORC_ASM_CODE(p,"  %s%s%s %s, %s, %s\n",
          dp_insn_names[opcode], orc_arm_cond_name(cond), (S ? "s" : ""),
          orc_arm_reg_name (Rd), orc_arm_reg_name (Rn), shifter);
    } else {
      /* opcode using Rd and val (mov, mvn) */
      code = arm_code_dp (cond, I, opcode, S, Rn, Rd, shifter_op);
      ORC_ASM_CODE(p,"  %s%s%s %s, %s\n",
          dp_insn_names[opcode], orc_arm_cond_name(cond), (S ? "s" : ""),
          orc_arm_reg_name (Rd), shifter);
    }
  } else {
    /* opcode does not change Rd, change status register (cmp, tst, ..) */
    code = arm_code_dp (cond, I, opcode, 1, Rn, 0, shifter_op);
    ORC_ASM_CODE(p,"  %s%s %s, %s\n",
        dp_insn_names[opcode], orc_arm_cond_name(cond), orc_arm_reg_name (Rn), shifter);
  }
  orc_arm_emit (p, code);
}

/* parallel instructions */
/*    3   2 2 2 2 2     2 2 1     1 1     1   1
 *  1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * | cond  |      mode     |   Rn  |  Rd   |0 0 0 0|  op   |  Rm   |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 */
#define arm_code_par(cond,mode,Rn,Rd,op,Rm) (((cond)<<28)|((mode)<<20)|(((Rn)&0xf)<<16)|(((Rd)&0xf)<<12)|((op)<<4)|((Rm)&0xf)|0xf00)

void
orc_arm_emit_par (OrcCompiler *p, int op, int mode, OrcArmCond cond,
    int Rd, int Rn, int Rm)
{
  orc_uint32 code;
  static const int par_op[] = {
    1, 3, 5, 7, 9, 15, 11, 5, 5
  };
  static const char *par_op_names[] = {
    "add16", "addsubx", "subaddx", "sub16", "add8", "sub8", "sel", "add", "sub"
  };
  static const int par_mode[] = {
    0x61, 0x62, 0x63, 0x65, 0x66, 0x67, 0x68, 0x10, 0x12, 0x14, 0x16
  };
  static const char *par_mode_names[] = {
    "s", "q", "sh", "u", "uq", "uh", "", "q", "q", "qd", "qd"
  };

  code = arm_code_par (cond, par_mode[mode], Rn, Rd, par_op[op], Rm);
  if (op == 7) {
    int tmp;
    /* gas does something screwy here */
    code &= ~0xf00;
    tmp = Rn;
    Rn = Rm;
    Rm = tmp;
  }
  ORC_ASM_CODE(p,"  %s%s%s %s, %s, %s\n",
      par_mode_names[mode], par_op_names[op], orc_arm_cond_name(cond),
      orc_arm_reg_name (Rd),
      orc_arm_reg_name (Rn),
      orc_arm_reg_name (Rm));
  orc_arm_emit (p, code);
}

/* extend instructions */
/*    3   2 2 2 2 2     2 2 1     1 1     1 1 1
 *  1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * | cond  |0 1 1 0 0 0 0 0|   Rn  |  Rd   |rot|0 0|0 1 1 1|  Rm   |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 */
#define arm_code_xt(op,cond,Rn,Rd,r8,Rm) (op|((cond)<<28)|(((Rn)&0xf)<<16)|(((Rd)&0xf)<<12)|((((r8)&0xf)&0x18)<<7)|((Rm)&0xf))

void
orc_arm_emit_xt (OrcCompiler *p, int op, OrcArmCond cond,
        int Rd, int Rn, int Rm, int r8)
{
  orc_uint32 code;
  char shifter[64];
  static const orc_uint32 xt_opcodes[] = {
    0x06800070, 0x06a00070, 0x06b00070, 0x06c00070, 0x06e00070, 0x06f00070
  };
  static const char *xt_insn_names[] = {
    "sxtb16", "sxtb", "sxth", "uxtb16", "uxtb", "uxth",
    "sxtab16", "sxtab", "sxtah", "uxtab16", "uxtab", "uxtah",
  };

  if (r8 & 0x18)
    sprintf (shifter, ", ROR #%d", r8 & 0x18);
  else
    shifter[0] = '\0';

  code = arm_code_xt (xt_opcodes[op], cond, Rn, Rd, r8, Rm);
  if (Rn < 15) {
    /* with Rn */
    ORC_ASM_CODE(p,"  %s%s %s, %s, %s%s\n",
        xt_insn_names[op], orc_arm_cond_name(cond),
        orc_arm_reg_name (Rd),
        orc_arm_reg_name (Rn),
        orc_arm_reg_name (Rm),
        shifter);
  } else {
    ORC_ASM_CODE(p,"  %s%s %s, %s%s\n",
        xt_insn_names[op], orc_arm_cond_name(cond),
        orc_arm_reg_name (Rd),
        orc_arm_reg_name (Rm),
        shifter);
  }
  orc_arm_emit (p, code);
}

#define arm_code_pkh(op,cond,Rn,Rd,sh,Rm) (op|((cond)<<28)|(((Rn)&0xf)<<16)|(((Rd)&0xf)<<12)|((sh)<<7)|((Rm)&0xf))
void
orc_arm_emit_pkh (OrcCompiler *p, int op, OrcArmCond cond,
    int Rd, int Rn, int Rm, int sh)
{
  orc_uint32 code;
  char shifter[64];
  static const orc_uint32 pkh_opcodes[] = { 0x06800010, 0x06800050 };
  static const char *pkh_insn_names[] = { "pkhbt", "pkhtb" };

  if (sh > 0) {
    sprintf (shifter, ", %s #%d",
        (op == 0 ? "LSL" : "ASR"), sh);
  } else {
    shifter[0] = '\0';
  }

  code = arm_code_pkh (pkh_opcodes[op], cond, Rn, Rd, sh, Rm);
  ORC_ASM_CODE(p,"  %s%s %s, %s, %s%s\n",
      pkh_insn_names[op], orc_arm_cond_name(cond),
      orc_arm_reg_name (Rd),
      orc_arm_reg_name (Rn),
      orc_arm_reg_name (Rm),
      shifter);
  orc_arm_emit (p, code);
}

/* extend instructions */
/*    3   2 2     2       2 1     1 1     1 1 1
 *  1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * | cond  |0 1 1 0|x x x|   sat   |  Rd   |   sh    |a|0 1|  Rm   |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 */
#define arm_code_sat(op,cond,sat,Rd,sh,a,Rm) (op|(((cond)&15)<<28)|(((sat)&31)<<16)|\
                                              (((Rd)&15)<<12)|(((sh)&31)<<7)|(((a)&1)<<6)|\
                                              ((Rm)&15))
void
orc_arm_emit_sat (OrcCompiler *p, int op, OrcArmCond cond,
        int Rd, int sat, int Rm, int sh, int asr)
{
  orc_uint32 code;
  char shifter[64];
  static const orc_uint32 sat_opcodes[] = { 0x06a00010, 0x06e00010, 0, 0 };
  static const char *sat_insn_names[] = { "ssat", "usat", "ssat16", "usat16" };
  static const int par_mode[] = { 0, 0, 0x6a, 0x6e };
  static const int par_op[] = { 0, 0, 3, 3 };

  if (sh > 0) {
    sprintf (shifter, ", %s #%d",
        (asr&1 ? "ASR" : "LSL"), sh);
  } else {
    shifter[0] = '\0';
  }

  if (op < 2) {
    code = arm_code_sat (sat_opcodes[op], cond, sat, Rd, sh, asr, Rm);
  } else {
    if (op == 3) {
      code = arm_code_par (cond, par_mode[op], sat, Rd, par_op[op], Rm);
    } else {
      code = arm_code_par (cond, par_mode[op], sat - 1, Rd, par_op[op], Rm);
    }
  }
  ORC_ASM_CODE(p,"  %s%s %s, #%d, %s%s\n",
      sat_insn_names[op], orc_arm_cond_name(cond),
      orc_arm_reg_name (Rd),
      sat,
      orc_arm_reg_name (Rm),
      shifter);
  orc_arm_emit (p, code);
}

#define arm_code_rv(op,cond,Rd,Rm) (op|(((cond)&15)<<28)|(((Rd)&15)<<12)|((Rm)&15))
void
orc_arm_emit_rv (OrcCompiler *p, int op, OrcArmCond cond,
    int Rd, int Rm)
{
  orc_uint32 code;
  static const orc_uint32 rv_opcodes[] = { 0x06bf0f30, 0x06bf0fb0 };
  static const char *rv_insn_names[] = { "rev", "rev16" };

  code = arm_code_rv (rv_opcodes[op], cond, Rd, Rm);
  ORC_ASM_CODE(p,"  %s%s %s, %s\n",
      rv_insn_names[op], orc_arm_cond_name(cond),
      orc_arm_reg_name (Rd), orc_arm_reg_name (Rm));
  orc_arm_emit (p, code);
}

void
orc_arm_flush_cache (OrcCode *code)
{
#if defined (HAVE_ARM) || defined (HAVE_AARCH64)
#ifdef __APPLE__
  sys_dcache_flush(code->code, code->code_size);
  sys_icache_invalidate(code->exec, code->code_size);
#elif defined (_WIN32)
  HANDLE h_proc = GetCurrentProcess();

  FlushInstructionCache(h_proc, code->code, code->code_size);

  if ((void *) code->exec != (void *) code->code)
    FlushInstructionCache(h_proc, code->exec, code->code_size);
#else
  __clear_cache (code->code, code->code + code->code_size);
  if ((void *) code->exec != (void *) code->code)
    __clear_cache (code->exec, code->exec + code->code_size);
#endif
#endif
}

void
orc_arm_emit_data (OrcCompiler *compiler, orc_uint32 data)
{
  if (compiler->target_flags & ORC_TARGET_CLEAN_COMPILE) {
    orc_arm_emit_nop (compiler);
  } else {
    ORC_ASM_CODE(compiler,"  .word 0x%08x\n", data);
    orc_arm_emit (compiler, data);
  }
}

void
orc_arm_loadw (OrcCompiler *compiler, int dest, int src1, int offset)
{
  orc_uint32 code;

  code = 0xe1d000b0;
  code |= (src1&0xf) << 16;
  code |= (dest&0xf) << 12;
  code |= (offset&0xf0) << 4;
  code |= offset&0x0f;

  ORC_ASM_CODE(compiler,"  ldrh %s, [%s, #%d]\n",
      orc_arm_reg_name (dest),
      orc_arm_reg_name (src1), offset);
  orc_arm_emit (compiler, code);
}

/** AArch64 instructions */

#define ARM64_MAX_OP_LEN 64

/** data processing instructions: Arithmetic
 *
 * Immediate
 *    3                   2                   1
 *  1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |b|op |1 0 0 0 1|sft|          imm12        |    Rn   |    Rd   |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 * Shifted register
 *    3                   2                   1
 *  1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |b|op |0 1 0 1 1|sft|0|    Rm   |   imm6    |    Rn   |    Rd   |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 * Extended register
 *    3                   2                   1
 *  1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |b|op |0 1 0 1 1|0 0|1|    Rm   | opt |imm3 |    Rn   |    Rd   |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 */

#define arm64_code_arith_imm(b,op,sft,imm,Rn,Rd) (0x11000000 | \
    ((((b)==64)&0x1)<<31) | (((op)&0x3)<<29) | (((sft)&0x3)<<22) | \
    (((imm)&0xfff)<<10) | (((Rn)&0x1f)<<5)  | ((Rd)&0x1f))

#define arm64_code_arith_reg(b,op,sft,Rm,imm,Rn,Rd) (0x0b000000 | \
    ((((b)==64)&0x1)<<31) | (((op)&0x3)<<29) | (((sft)&0x3)<<22) | \
    (((Rm)&0x1f)<<16) | (((imm)&0x3f)<<10) | (((Rn)&0x1f)<<5)  | ((Rd)&0x1f))

#define arm64_code_arith_ext(b,op,Rm,opt,imm,Rn,Rd) (0x0b200000 | \
    ((((b)==64)&0x1)<<31) | (((op)&0x3)<<29) | (((Rm)&0x1f)<<16) | \
    (((opt)&0x7)<<13) | (((imm)&0x7)<<10) | (((Rn)&0x1f)<<5) | ((Rd)&0x1f))

void
orc_arm64_emit_am (OrcCompiler *p, OrcArm64RegBits bits, OrcArm64DP opcode,
    OrcArm64Type type, int opt, int Rd, int Rn, int Rm, orc_uint64 val)
{
  orc_uint32 code;
  orc_uint32 imm;

  int shift, extend;

  static const char *insn_names[] = {
    "add", "adds", "sub", "subs",
  };
  static const char *insn_alias[] = {
    "ERROR", "cmn", "ERROR", "cmp",
  };
  static const char *shift_names[] = {
    "lsl", "lsr", "asr", "ror"
  };
  static const char *extend_names[] = {
    "uxtb", "uxth", "uxtw", "uxtx",
    "sxtb", "sxth", "sxtw", "sxtx"
  };

  int alias_rd;
  char opt_rm[ARM64_MAX_OP_LEN];

  opcode -= ORC_ARM64_DP_ADD;

  if (opcode >= sizeof(insn_names)/sizeof(insn_names[0])) {
    ORC_COMPILER_ERROR(p, "unsupported opcode %d", opcode);
    return;
  }

  /** if a reg is not specified, it's regarded as alias; set it to SP (== 0b11111) */
  alias_rd = 0;
  if (Rd == 0) {
    Rd = ORC_ARM64_SP;
    alias_rd = 1;
  }

  memset (opt_rm, '\x00', ARM64_MAX_OP_LEN);

  switch (type) {
    case ORC_ARM64_TYPE_IMM:      /** immediate */
      /**, #imm */
      shift = 0;
      imm = (orc_uint32) val;

      /** Support up to 24-bit immediate value, explicitly shifted left (LSL) by 0 or 12 */
      if (val > 0xfff) {
        if (val > 0xffffff) {
          ORC_COMPILER_ERROR(p, "imm is out-of-range %llx", val);
          return;
        }
        if (val & 0xfff) {
          ORC_WARNING("offset is trucated %llx", val);
        }
        imm >>= 12;
        shift = 1;
      }

      if (shift)
        snprintf (opt_rm, ARM64_MAX_OP_LEN, ", #%u, lsl #12", imm);
      else
        snprintf (opt_rm, ARM64_MAX_OP_LEN, ", #%u", imm);

      code = arm64_code_arith_imm (bits, opcode, shift, imm, Rn, Rd);
      break;
    case ORC_ARM64_TYPE_REG:  /** shifted register */
      /**, <Rm>, shift #amount */
      shift = opt;
      imm = (orc_uint32) val;

      if (shift >= sizeof(shift_names)/sizeof(shift_names[0])) {
        ORC_COMPILER_ERROR(p, "unsupported shift %d", shift);
        return;
      }

      if (val > 0) {
        if (val > 63) {
          ORC_COMPILER_ERROR(p, "shift is out-of-range %llx", val);
          return;
        }

        snprintf (opt_rm, ARM64_MAX_OP_LEN, ", %s, %s #%u",
            orc_arm64_reg_name (Rm, bits), shift_names[shift], imm);
      } else
        snprintf (opt_rm, ARM64_MAX_OP_LEN, ", %s", orc_arm64_reg_name (Rm, bits));

      code = arm64_code_arith_reg (bits, opcode, shift, Rm, imm, Rn, Rd);
      break;
    case ORC_ARM64_TYPE_EXT:  /** extended register */
      /**, <Rm>, extend #amount */
      extend = opt;
      imm = (orc_uint32) val;

      if (extend >= sizeof(extend_names)/sizeof(extend_names[0])) {
        ORC_COMPILER_ERROR(p, "unsupported extend %d", extend);
        return;
      }

      if (val > 0) {
        if (val > 4) {
          ORC_COMPILER_ERROR(p, "shift is out-of-range %llx\n", val);
          return;
        }
        /** its width is determined by extend; '0bx11' ==> 64-bit reg */
        snprintf (opt_rm, ARM64_MAX_OP_LEN, ", %s, %s #%u",
            orc_arm64_reg_name (Rm, extend & 0x3 ? ORC_ARM64_REG_64 : ORC_ARM64_REG_32),
            extend_names[extend], imm);
      } else
        snprintf (opt_rm, ARM64_MAX_OP_LEN, ", %s", orc_arm64_reg_name (Rm, bits));

      code = arm64_code_arith_ext(bits, opcode, Rm, extend, imm, Rn, Rd);
      break;
    default:
      ORC_COMPILER_ERROR(p, "unknown data processing type %d", type);
      return;
  }

  /** it's preferred to use alias names if exists */
  if (alias_rd) {
    ORC_ASM_CODE(p, "  %s %s%s\n", insn_alias[opcode],
        orc_arm64_reg_name(Rn, bits), opt_rm);
  } else {
    ORC_ASM_CODE(p, "  %s %s, %s%s\n", insn_names[opcode],
        orc_arm64_reg_name(Rd, bits), orc_arm64_reg_name(Rn, bits), opt_rm);
  }

  orc_arm_emit (p, code);
}

/** data processing instructions: Logical
 *
 * Immediate
 *    3                   2                   1
 *  1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |b|op |1 0 0 1 0 0|         imm13           |    Rn   |    Rd   |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 * Shifted register
 *    3                   2                   1
 *  1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |b|op |0 1 0 1 0|sft|0|    Rm   |   imm6    |    Rn   |    Rd   |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 */

#define arm64_code_logical_imm(b,op,imm,Rn,Rd) (0x12000000 | \
    ((((b)==64)&0x1)<<31) | (((op)&0x3)<<29) | (((imm)&0x1fff)<<10) | \
    (((Rn)&0x1f)<<5)  | ((Rd)&0x1f))

#define arm64_code_logical_reg(b,op,sft,Rm,imm,Rn,Rd) (0x0a000000 | \
    ((((b)==64)&0x1)<<31) | (((op)&0x3)<<29) | (((sft)&0x3)<<22) | \
    (((Rm)&0x1f)<<16) | (((imm)&0x3f)<<10) | (((Rn)&0x1f)<<5)  | ((Rd)&0x1f))

/**
 * check if it's a non-empty sequence of ones starting at the LSB with the remainder zero
 * e.g., mask_ones(0x0000FFFF) == true
 */
#define mask_ones(val) ((val) && (((val) + 1) & (val)) == 0)
/**
 * check if it contains a non-empty sequence of ones with the remainder zero
 * e.g., mask_shifted_ones(0x0000FF00) == true
 */
#define mask_shifted_ones(val) ((val) && mask_ones(((val) - 1) | (val)))

#if defined(__GNUC__)
#define count_trailing_zeros(val) __builtin_ctzll(val)
#define count_leading_zeros(val) __builtin_clzll(val)
#else
static int
count_trailing_zeros (orc_uint64 val)
{
  int i, count = 0;

  for (i = 0; i < 64; i++) {
    if ((val >> i) & 1)
      break;
    count++;
  }

  return count;
}
static int
count_leading_zeros (orc_uint64 val)
{
  int i, count = 0;

  for (i = 63; i >= 0; i--) {
    if ((val >> i) & 1)
      break;
    count++;
  }

  return count;
}
#endif
#define count_trailing_ones(val) count_trailing_zeros(~val)
#define count_leading_ones(val) count_leading_zeros(~val)

/**
 * Encode a logical immediate value (code reference: LLVM)
 * 32-bit variant: immr:imms
 * 64-bit variant: N:immr:imms
 */
static int
encode_logical_imm (unsigned int size, orc_uint64 val, orc_uint32 *encoded)
{
  orc_uint64 mask;
  orc_uint32 I, CTO, CLO;
  orc_uint32 immr, imms, N;

  if (size > 64)
    return -1;

  /**
   * immediate values of all-zero and all-cones are not encoded.
   * Requires at least one non-zero bit, and one zero bit.
   */
  if (val == 0ULL || val == ~0ULL ||
      (size != 64 && (val >> size != 0 || val == (~0ULL >> (64 - size)))))
    return -2;

  /** decide the element size (i.e., 2, 4, 8, 16, 32 or 64 bits) */
  do {
    size /= 2;
    mask = (1ULL << size) - 1;
    if ((val & mask) != ((val >> size) & mask)) {
      size *= 2;
      break;
    }
  } while (size > 2);

  /** decide the rotations to make the element be: 0^m 1^n */
  mask = ((orc_uint64)~0ULL) >> (64 - size);
  val &= mask;

  if (mask_shifted_ones (val)) {
    I = count_trailing_zeros (val);
    CTO = count_trailing_ones (val >> I);
  } else {
    val |= ~mask;
    if (!mask_shifted_ones (~val))
      return 0;
    CLO = count_leading_ones (val);
    I = 64 - CLO;
    CTO = CLO + count_trailing_ones (val) - (64 - size);
  }

  /** encode N:immr:imms */
  immr = (size - I) & (size - 1);
  imms = ~(size-1) << 1;
  imms |= (CTO-1);
  N = ((imms >> 6) & 1) ^ 1;

  *encoded = (N << 12) | (immr << 6) | (imms & 0x3f);

  return 0;
}

void
orc_arm64_emit_lg (OrcCompiler *p, OrcArm64RegBits bits, OrcArm64DP opcode,
    OrcArm64Type type, int opt, int Rd, int Rn, int Rm, orc_uint64 val)
{
  orc_uint32 code;
  orc_uint32 imm = 0xffffffff;

  int shift, ret;

  static const char *insn_names[] = {
    "and", "orr", "eor", "ands"
  };
  static const char *insn_alias[] = {
    "ERROR", "mov", "ERROR", "tst"
  };
  static const char *shift_names[] = {
    "lsl", "lsr", "asr", "ror"
  };

  int alias_rd, alias_rn;
  char opt_rm[ARM64_MAX_OP_LEN];

  opcode -= ORC_ARM64_DP_AND;

  if (opcode >= sizeof(insn_names)/sizeof(insn_names[0])) {
    ORC_COMPILER_ERROR(p, "unsupported opcode %d", opcode);
    return;
  }

  /** if a reg is not specified, it's regarded as alias; set it to SP (== 0b11111) */
  alias_rd = alias_rn = 0;
  if (Rd == 0) {
    Rd = ORC_ARM64_SP;
    alias_rd = 1;
  }
  if (Rn == 0) {
    Rn = ORC_ARM64_SP;
    alias_rn = 1;
  }

  memset (opt_rm, '\x00', ARM64_MAX_OP_LEN);

  switch (type) {
    case ORC_ARM64_TYPE_IMM:      /** immediate */
      /**, #imm */
      if (val == 0) {
        ORC_COMPILER_ERROR(p, "zero imm is not supported");
        return;
      }

      ret = encode_logical_imm (bits, val, &imm);
      if (ret) {
        ORC_COMPILER_ERROR(p, "wrong immediate value %llx", val);
        return;
      }

      snprintf (opt_rm, ARM64_MAX_OP_LEN, ", #0x%08x", (orc_uint32) val);

      code = arm64_code_logical_imm (bits, opcode, imm, Rn, Rd);
      break;
    case ORC_ARM64_TYPE_REG:      /** shifted register */
      /**, <Rm>, shift #amount */
      shift = opt;
      imm = (orc_uint32) val;

      if (shift >= sizeof(shift_names)/sizeof(shift_names[0])) {
        ORC_COMPILER_ERROR(p, "unsupported shift %d", shift);
        return;
      }

      if (val > 0) {
        if (val > 63) {
          ORC_COMPILER_ERROR(p, "shift is out-of-range %llx", val);
          return;
        }

        snprintf (opt_rm, ARM64_MAX_OP_LEN, ", %s, %s #%u",
            orc_arm64_reg_name (Rm, bits), shift_names[shift], imm);
      } else
        snprintf (opt_rm, ARM64_MAX_OP_LEN, ", %s", orc_arm64_reg_name (Rm, bits));

      code = arm64_code_logical_reg (bits, opcode, shift, Rm, imm, Rn, Rd);
      break;
    default:
      ORC_COMPILER_ERROR(p, "unknown data processing type %d", type);
      return;
  }

  /** it's preferred to use alias names if exists */
  if (alias_rd) {
    ORC_ASM_CODE(p, "  %s %s%s\n", insn_alias[opcode],
        orc_arm64_reg_name(Rn, bits), opt_rm);
  } else if (alias_rn) {
    ORC_ASM_CODE(p, "  %s %s%s\n", insn_alias[opcode],
        orc_arm64_reg_name(Rd, bits), opt_rm);
  } else {
    ORC_ASM_CODE(p, "  %s %s, %s%s\n", insn_names[opcode],
        orc_arm64_reg_name(Rd, bits), orc_arm64_reg_name(Rn, bits), opt_rm);
  }

  orc_arm_emit (p, code);
}

/** data processing instructions: move wide
 *
 * General formats
 *    3                   2                   1
 *  1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |b|op |1 0 0 1 0 1|hw |              imm16            |    Rd   |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 */

#define arm64_code_mov_wide(b,op,hw,imm,Rd) (0x12800000 | ((((b)==64)&0x1)<<31) | \
    (((op)&0x3)<<29) | (((hw)&0x3)<<21) | (((imm)&0xffff)<<5) | ((Rd)&0x1f))

void
orc_arm64_emit_mov_wide (OrcCompiler *p, OrcArm64RegBits bits, int mov_op, int hw,
    int Rd, orc_uint64 val)
{
  orc_uint16 imm;
  orc_uint32 code;

  static const char *mov_names[] = {
    "movn", "ERROR", "movz", "movk"
  };
  char opt_lsl[ARM64_MAX_OP_LEN];

  if (mov_op >= sizeof(mov_names)/sizeof(mov_names[0])) {
    ORC_COMPILER_ERROR(p, "unsupported mov opcode %d", mov_op);
    return;
  }

  if (val > 65535) {
    ORC_COMPILER_ERROR(p, "unsupported amount of shift %llu", val);
    return;
  }

  if (bits == ORC_ARM64_REG_64) {
    if (!(hw == 0 || hw == 16 || hw == 32 || hw == 48)) {
      ORC_COMPILER_ERROR(p, "unsupported hw shift %d", hw);
      return;
    }
  } else {
    if (!(hw == 0 || hw == 16)) {
      ORC_COMPILER_ERROR(p, "unsupported hw shift %d", hw);
      return;
    }
  }

  memset (opt_lsl, '\x00', ARM64_MAX_OP_LEN);
  if (hw > 0) {
    snprintf (opt_lsl, ARM64_MAX_OP_LEN, ", lsl #%d", hw);
  }

  hw /= 16;
  imm = val;
  code = arm64_code_mov_wide(bits, mov_op, hw, imm, Rd);

  ORC_ASM_CODE(p, "  %s %s, #%u%s\n",
      /** movz has one alias condition */
      (mov_op == 2) && !(imm == 0 && hw != 0) ? "mov" : mov_names[mov_op],
      orc_arm64_reg_name(Rd, bits),
      imm, opt_lsl);

  orc_arm_emit (p, code);
}

/** data processing instructions: Shift (reg)
 *
 * General formats
 *    3                   2                   1
 *  1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |b|0 0|1 1 0 1 0 1 1 0|    Rm   |0 0 1 0|sft|    Rn   |    Rd   |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 */

#define arm64_code_shift(b,Rm,sft,Rn,Rd) (0x1ac02000 | ((((b)==64)&0x1)<<31) | \
    (((Rm)&0x1f)<<16) | (((sft)&0x3)<<10) | (((Rn)&0x1f)<<5)  | ((Rd)&0x1f))

void
orc_arm64_emit_sft (OrcCompiler *p, OrcArm64RegBits bits, OrcArmShift shift,
    int Rd, int Rn, int Rm)
{
  orc_uint32 code;

  static const char *shift_names[] = {
    "lsl", "lsr", "asr", "ror"
  };

  if (shift >= sizeof(shift_names)/sizeof(shift_names[0])) {
    ORC_COMPILER_ERROR(p, "unsupported shift %d", shift);
    return;
  }

  code = arm64_code_shift(bits, Rm, shift, Rn, Rd);

  ORC_ASM_CODE(p, "  %s %s, %s, %s\n",
      shift_names[shift],
      orc_arm64_reg_name(Rd, bits),
      orc_arm64_reg_name(Rn, bits),
      orc_arm64_reg_name(Rm, bits));

  orc_arm_emit (p, code);
}

/** data processing instructions: Bitfield Move
 *
 * General formats
 *    3                   2                   1
 *  1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |b|op |1 0 0 1 1 0|N|    immr   |    imms   |    Rn   |    Rd   |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 * Note that Bitfiled Move is usually accessed via one of its aliases
 */

#define arm64_code_bfm(b,opcode,immr,imms,Rn,Rd) (0x13000000 | ((((b)==64)&0x1)<<31) | \
    (((opcode)&0x3)<<29) | ((((b)==64)&0x1)<<22) | (((immr)&0x3f)<<16) | (((imms)&0x3f)<<10) | \
    (((Rn)&0x1f)<<5) | ((Rd)&0x1f))

/** Return 1 if ubfx or sbfx is preferred. Must exclude more specific aliases */
static int bfx_preferred (OrcArm64RegBits bits, int is_unsigned,
    orc_uint32 imms, orc_uint32 immr)
{
  if (imms < immr)
    return 0;

  /** must not match LSR/ASR/LSL alias */
  if (imms == 0x1f)
    return 0;

  /** must not match UXTx/SXTx alias */
  if (immr == 0) {
    if (bits == ORC_ARM64_REG_32) {
      if (imms == 0x7 || imms == 0xf)
        return 0;
    } else if (is_unsigned) {
      if (imms == 0x7 || imms == 0xf || imms == 0x1f)
        return 0;
    }
  }

  return 1;
}

void
orc_arm64_emit_bfm (OrcCompiler *p, OrcArm64RegBits bits, OrcArm64DP opcode,
    int Rd, int Rn, orc_uint32 immr, orc_uint32 imms)
{
  orc_uint32 code;
  int alias = -1;

  static const char *insn_names[3] = {
    "sbfm", "bfm", "ubfm"
  };
  static const char *insn_alias[3][6] = {
    {"asr","sbfiz","sbfx","sxtb","sxth","sxtw"},
    {"bfc","bfi","bfxil", "ERROR","ERROR","ERROR"},
    {"lsl","lsr","ubfiz","ubfx","uxtb","uxth"}
  };

  char opt_immr[ARM64_MAX_OP_LEN];
  char opt_imms[ARM64_MAX_OP_LEN];

  memset (opt_immr, '\x00', ARM64_MAX_OP_LEN);
  memset (opt_imms, '\x00', ARM64_MAX_OP_LEN);

  /** find its alias */
  switch (opcode) {
    case ORC_ARM64_DP_SBFM:
      if (imms == 0x1f) {
        if (bits == ORC_ARM64_REG_64)
          imms |= 0x20;
        snprintf (opt_immr, ARM64_MAX_OP_LEN, ", #%u", immr);
        alias = 0;
      } else if (imms < immr) {
        snprintf (opt_immr, ARM64_MAX_OP_LEN, ", #%u", immr);
        snprintf (opt_imms, ARM64_MAX_OP_LEN, ", #%u", imms);
        alias = 1;
      } else if (bfx_preferred(bits, 0, imms, immr)) {
        snprintf (opt_immr, ARM64_MAX_OP_LEN, ", #%u", immr);
        snprintf (opt_imms, ARM64_MAX_OP_LEN, ", #%u", imms);
        alias = 2;
      } else if (immr == 0) {
        if (imms == 0x7)
          alias = 3;
        else if (imms == 0xf)
          alias = 4;
        else if (imms == 0x1f)
          alias = 5;
      }
      break;
    case ORC_ARM64_DP_BFM:
      if (imms < immr) {
        if (Rn == 0x1f) {
          snprintf (opt_immr, ARM64_MAX_OP_LEN, ", #%u", immr);
          alias = 0;
        } else {
          snprintf (opt_immr, ARM64_MAX_OP_LEN, ", #%u", immr);
          snprintf (opt_imms, ARM64_MAX_OP_LEN, ", #%u", imms);
          alias = 1;
        }
      } else {
        snprintf (opt_immr, ARM64_MAX_OP_LEN, ", #%u", immr);
        snprintf (opt_imms, ARM64_MAX_OP_LEN, ", #%u", imms);
        alias = 2;
      }
      break;
    case ORC_ARM64_DP_UBFM:
      if (imms == 0x1f) {
        if (bits == ORC_ARM64_REG_64)
          imms |= 0x20;
        snprintf (opt_immr, ARM64_MAX_OP_LEN, ", #%u", immr);
        alias = 1;
      } else if (imms + 1 == immr) {
        if (bits == ORC_ARM64_REG_64)
          imms |= 0x20;
        snprintf (opt_immr, ARM64_MAX_OP_LEN, ", #%u", immr);
        alias = 0;
      } else if (imms < immr) {
        snprintf (opt_immr, ARM64_MAX_OP_LEN, ", #%u", immr);
        snprintf (opt_imms, ARM64_MAX_OP_LEN, ", #%u", imms);
        alias = 2;
      } else if (bfx_preferred(bits, 1, imms, immr)) {
        snprintf (opt_immr, ARM64_MAX_OP_LEN, ", #%u", immr);
        snprintf (opt_imms, ARM64_MAX_OP_LEN, ", #%u", imms);
        alias = 3;
      } else if (immr == 0) {
        if (imms == 0x7)
          alias = 4;
        else if (imms == 0xf)
          alias = 5;
      }
      break;
    default:
      ORC_COMPILER_ERROR(p, "unknown opcode %d", opcode);
      return;
  }

  opcode -= ORC_ARM64_DP_SBFM;

  code = arm64_code_bfm(bits, opcode, immr, imms, Rn, Rd);

  if (alias != -1) {
    ORC_ASM_CODE(p, "  %s %s, %s%s%s\n",
        insn_alias[opcode][alias],
        orc_arm64_reg_name(Rd, bits),
        orc_arm64_reg_name(Rn, bits),
        opt_immr, opt_imms);
  } else {
    ORC_ASM_CODE(p, "  %s %s, %s, #%u, #%u\n",
        insn_names[opcode],
        orc_arm64_reg_name(Rd, bits),
        orc_arm64_reg_name(Rn, bits),
        immr, imms);
  }

  orc_arm_emit (p, code);
}

/** data processing instructions: Extract, alias of ROR (imm)
 *
 *    3                   2                   1
 *  1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |b|0 0|1 0 0 1 1 1|N|0|    Rm   |    imms   |    Rn   |    Rd   |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 */

#define arm64_code_extr(b,Rm,imms,Rn,Rd) (0x13800000 | ((((b)==64)&0x1)<<31) | \
    ((((b)==64)&0x1)<<22) | (((Rm)&0x1f)<<16) | (((imms)&0x3f)<<10) | \
    (((Rn)&0x1f)<<5) | ((Rd)&0x1f))

void
orc_arm64_emit_extr (OrcCompiler *p, OrcArm64RegBits bits,
    int Rd, int Rn, int Rm, orc_uint32 imm)
{
  orc_uint32 code;

  code = arm64_code_extr (bits, Rm, imm, Rn, Rd);

  if (Rn == Rm) { /** ROR (imm) */
    if (bits == ORC_ARM64_REG_32 && (imm & 0x20)) {
      ORC_COMPILER_ERROR(p, "invalid immediate value 0x%08x", imm);
      return;
    }

    ORC_ASM_CODE(p, "  ror %s, %s, #%u\n",
      orc_arm64_reg_name(Rd, bits),
      orc_arm64_reg_name(Rn, bits),
      imm);
  } else {
    ORC_ASM_CODE(p, "  extr %s, %s, %s, #%u\n",
      orc_arm64_reg_name(Rd, bits),
      orc_arm64_reg_name(Rn, bits),
      orc_arm64_reg_name(Rm, bits),
      imm);
  }

  orc_arm_emit (p, code);
}

/** memory access instructions
 *
 * Literal (LDR only)
 *    3                   2                   1
 *  1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |0 b|0 1 1|0|0 0|                imm19                |    Rt   |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 * Register Signed offset (Post-/Pre-index)
 *    3                   2                   1
 *  1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |1 b|1 1 1|0|0 0|op |0|       imm9      |P 1|    Rn   |    Rt   |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 * Register Unsigned offset
 *    3                   2                   1
 *  1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |1 b|1 1 1|0|0 1|op |         imm12         |   Rn    |    Rt   |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 * Register Extended
 *    3                   2                   1
 *  1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |1 b|1 1 1|0|0 0|op |1|    Rm   | opt |S|1 0|    Rn   |    Rt   |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 */

#define arm64_code_mem_literal(b,imm,Rt) (0x18000000 | ((((b)==64)&0x1)<<30) | \
    (((imm)&0x7ffff)<<5) | ((Rt)&0x1f))

#define arm64_code_mem_signed(b,op,imm,P,Rn,Rt) (0xb8000400 | ((((b)==64)&0x1)<<30) | \
    (((op)&0x3)<<22) | (((imm)&0x3f)<<12) | (((P)&0x1)<<11) | (((Rn)&0x1f)<<5) | ((Rt)&0x1f))

#define arm64_code_mem_unsigned(b,op,imm,Rn,Rt) (0xb9000000 | ((((b)==64)&0x1)<<30) | \
    (((op)&0x3)<<22) | (((imm)&0xfff)<<10) | (((Rn)&0x1f)<<5) | ((Rt)&0x1f))

#define arm64_code_mem_extended(b,op,Rm,opt,S,Rn,Rt) (0xb8200800 | ((((b)==64)&0x1)<<30) | \
    (((op)&0x3)<<22) | (((Rm)&0x1f)<<16) | (((opt)&0x7)<<13) | (((S)&0x1)<<12) | \
    (((Rn)&0x1f)<<5) | ((Rt)&0x1f))

void
orc_arm64_emit_mem (OrcCompiler *p, OrcArm64RegBits bits, OrcArm64Mem opcode,
    OrcArm64Type type, int opt, int Rt, int Rn, int Rm, orc_uint32 val)
{
  orc_uint32 code;
  orc_uint32 amount;
  orc_int32 imm;

  int is_signed, extend, S;

  static const char *insn_names[3] = {
    "str", "ldr"
  };
  static const char *extend_names[] = {
    "ERROR", "ERROR", "uxtw", "lsl",
    "ERROR", "ERROR", "sxtw", "sxtx"
  };

  char opt_rn[ARM64_MAX_OP_LEN];
  char opt_rm[ARM64_MAX_OP_LEN];

  if (opcode >= sizeof(insn_names)/sizeof(insn_names[0])) {
    ORC_COMPILER_ERROR(p, "unsupported opcode %d", opcode);
    return;
  }

  memset (opt_rn, '\x00', ARM64_MAX_OP_LEN);
  memset (opt_rm, '\x00', ARM64_MAX_OP_LEN);

  switch (type) {
    case ORC_ARM64_TYPE_IMM:
      if (opcode != ORC_ARM64_MEM_LDR) {
        ORC_COMPILER_ERROR(p, "str with immediate is not permitted\n");
        return;
      }

      if (bits == ORC_ARM64_REG_64) {
        imm = val/8;
      } else {
        imm = val/4;
      }

      if (imm > 4095) {
        ORC_COMPILER_ERROR(p, "out-of-range immediate 0x%lx\n", val);
        return;
      }

      if (imm == 0) {
        int label = opt;
        /** resolve the actual address diff in fixup code */
        orc_arm_add_fixup (p, label, 2);
        snprintf (opt_rn, ARM64_MAX_OP_LEN, ", .L%d", label);
      } else {
        snprintf (opt_rn, ARM64_MAX_OP_LEN, ", 0x%08x", val);
      }

      code = arm64_code_mem_literal (bits, imm, Rt);
      break;
    case ORC_ARM64_TYPE_REG:
      imm = val;
      is_signed = opt;

      if (is_signed) { /** signed offset */
        if (imm > 0xff || imm < -0xff) {
          ORC_COMPILER_ERROR(p, "simm is out-of-range %x\n", imm);
          return;
        }

        if (is_signed == 1) { /** pre index */
          snprintf (opt_rn, ARM64_MAX_OP_LEN, ", [%s", orc_arm64_reg_name(Rn, bits));
          snprintf (opt_rm, ARM64_MAX_OP_LEN, ", #%d]!", imm);

          code = arm64_code_mem_signed (bits, opcode, imm, 1, Rn, Rt);
        } else {              /** post index */
          snprintf (opt_rn, ARM64_MAX_OP_LEN, ", [%s]", orc_arm64_reg_name(Rn, bits));
          snprintf (opt_rm, ARM64_MAX_OP_LEN, ", #%d", imm);

          code = arm64_code_mem_signed (bits, opcode, imm, 0, Rn, Rt);
        }
      } else {  /** unsigned offset */
        if (imm != 0) {
          snprintf (opt_rn, ARM64_MAX_OP_LEN, ", [%s", orc_arm64_reg_name(Rn, bits));
          snprintf (opt_rm, ARM64_MAX_OP_LEN, ", #%d]", imm);
        } else {
          snprintf (opt_rn, ARM64_MAX_OP_LEN, ", [%s]", orc_arm64_reg_name(Rn, bits));
        }

        if (bits == ORC_ARM64_REG_64) {
          if (imm < 0 || imm > 0xfff * 8)
            ORC_COMPILER_ERROR(p, "imm is Out-of-range %x\n", imm);
          imm /= 8;
        } else {
          if (imm < 0 || imm > 0xfff * 4)
            ORC_COMPILER_ERROR(p, "imm is Out-of-range %x\n", imm);
          imm /= 4;
        }

        code = arm64_code_mem_unsigned (bits, opcode, imm, Rn, Rt);
      }
      break;
    case ORC_ARM64_TYPE_EXT:
      extend = opt;

      if ((extend >= sizeof(extend_names)/sizeof(extend_names[0])) ||
          !strncmp (extend_names[extend], "ERROR", 5)) {
        ORC_COMPILER_ERROR(p, "unsupported extend %d\n", extend);
        return;
      }

      snprintf (opt_rn, ARM64_MAX_OP_LEN, ", [%s", orc_arm64_reg_name(Rn, bits));

      amount = val;
      if (amount > 0) {
        if (bits == ORC_ARM64_REG_64 && amount != 3) {
          ORC_COMPILER_ERROR(p, "unsupported amount %d\n", amount);
          return;
        }
        if (bits == ORC_ARM64_REG_32 && amount != 2) {
          ORC_COMPILER_ERROR(p, "unsupported amount %d\n", amount);
          return;
        }
        snprintf (opt_rm, ARM64_MAX_OP_LEN, ", %s, %s #%u]",
            orc_arm64_reg_name(Rm, bits), extend_names[extend], amount);

        S = 1;
      } else {
        if (extend == 3) {   /** LSL */
          snprintf (opt_rm, ARM64_MAX_OP_LEN, ", %s]", orc_arm64_reg_name(Rm, bits));
        } else {
          snprintf (opt_rm, ARM64_MAX_OP_LEN, ", %s, %s]",
              orc_arm64_reg_name(Rm, bits), extend_names[extend]);
        }

        S = 0;
      }

      code = arm64_code_mem_extended (bits, opcode, Rm, extend, S, Rn, Rt);
      break;
    default:
      ORC_COMPILER_ERROR(p, "unsupported type %d\n", type);
      return;
  }

  ORC_ASM_CODE(p, "  %s %s%s%s\n",
      insn_names[opcode],
      orc_arm64_reg_name(Rt, bits),
      opt_rn, opt_rm);

  orc_arm_emit (p, code);
}

/** memory access instructions (pair)
 *
 *    3                   2                   1
 *  1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |b 0|1 0 1|0| opt |L|     imm7    |   Rt2   |    Rn   |    Rt   |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 */

#define arm64_code_mem_pair(b,opt,L,imm,Rt2,Rn,Rt) (0x40000000 | ((((b)==64)&0x1)<<31) | \
    (((opt)&0x7)<<23) | (((L)&0x1)<<22) | (((imm)&0x7f)<<15) | (((Rt2)&0x1f)<<10) | \
    (((Rn)&0x1f)<<5) | ((Rt)&0x1f))

void
orc_arm64_emit_mem_pair (OrcCompiler *p, OrcArm64RegBits bits, OrcArm64Mem opcode,
    int opt, int Rt, int Rt2, int Rn, orc_int32 imm)
{
  orc_uint32 code;

  static const char *insn_names[3] = {
    "stp", "ldp"
  };

  char opt_rn[ARM64_MAX_OP_LEN];

  if (opcode >= sizeof(insn_names)/sizeof(insn_names[0])) {
    ORC_COMPILER_ERROR(p, "unsupported opcode %d", opcode);
    return;
  }

  memset (opt_rn, '\x00', ARM64_MAX_OP_LEN);

  switch (opt) {
    case 1: /** post-index */
      snprintf (opt_rn, ARM64_MAX_OP_LEN, ", [%s], #%d", orc_arm64_reg_name(Rn, bits), imm);
      break;
    case 2: /** signed offset */
      if (imm) {
        snprintf (opt_rn, ARM64_MAX_OP_LEN, ", [%s, #%d]", orc_arm64_reg_name(Rn, bits), imm);
      } else {
        snprintf (opt_rn, ARM64_MAX_OP_LEN, ", [%s]", orc_arm64_reg_name(Rn, bits));
      }
      break;
    case 3: /** pre-index */
      snprintf (opt_rn, ARM64_MAX_OP_LEN, ", [%s, #%d]!", orc_arm64_reg_name(Rn, bits), imm);
      break;
    default:
      ORC_COMPILER_ERROR(p, "unsupported variant %d\n", opt);
      return;
  }

  if (bits == ORC_ARM64_REG_64) {
    imm /= 8;
  } else {
    imm /= 4;
  }

  if (imm < -64 || imm > 63) {
    ORC_COMPILER_ERROR(p, "imm is Out-of-range\n");
    return;
  }

  code = arm64_code_mem_pair (bits, opt, opcode, imm, Rt2, Rn, Rt);

  ORC_ASM_CODE(p, "  %s %s, %s%s\n",
      insn_names[opcode],
      orc_arm64_reg_name(Rt, bits),
      orc_arm64_reg_name(Rt2, bits),
      opt_rn);

  orc_arm_emit (p, code);
}

/** Return from subroutine */

void
orc_arm64_emit_ret (OrcCompiler *p, int Rn)
{
  orc_uint32 code;

  code = 0xd65f0000 | ((Rn & 0x1f) << 5);

  ORC_ASM_CODE (p, "  ret %s\n",
      Rn == ORC_ARM64_LR ? "" : orc_arm64_reg_name (Rn, ORC_ARM64_REG_64));

  orc_arm_emit (p, code);
}