src/buildvm_asm.c

   1 /*
   2 ** LuaJIT VM builder: Assembler source code emitter.
   3 ** Copyright (C) 2005-2012 Mike Pall. See Copyright Notice in luajit.h
   4 */
   5
   6 #include "buildvm.h"
   7 #include "lj_bc.h"
   8
   9 /* ------------------------------------------------------------------------ */
  10
  11 #if LJ_TARGET_X86ORX64
  12 /* Emit bytes piecewise as assembler text. */
  13 static void emit_asm_bytes(BuildCtx *ctx, uint8_t *p, int n)
  14 {
  15   int i;
  16   for (i = 0; i < n; i++) {
  17     if ((i & 15) == 0)
  18       fprintf(ctx->fp, "\t.byte %d", p[i]);
  19     else
  20       fprintf(ctx->fp, ",%d", p[i]);
  21     if ((i & 15) == 15) putc('\n', ctx->fp);
  22   }
  23   if ((n & 15) != 0) putc('\n', ctx->fp);
  24 }
  25
  26 /* Emit relocation */
  27 static void emit_asm_reloc(BuildCtx *ctx, int type, const char *sym)
  28 {
  29   switch (ctx->mode) {
  30   case BUILD_elfasm:
  31     if (type)
  32       fprintf(ctx->fp, "\t.long %s-.-4\n", sym);
  33     else
  34       fprintf(ctx->fp, "\t.long %s\n", sym);
  35     break;
  36   case BUILD_coffasm:
  37     fprintf(ctx->fp, "\t.def %s; .scl 3; .type 32; .endef\n", sym);
  38     if (type)
  39       fprintf(ctx->fp, "\t.long %s-.-4\n", sym);
  40     else
  41       fprintf(ctx->fp, "\t.long %s\n", sym);
  42     break;
  43   default:  /* BUILD_machasm for relative relocations handled below. */
  44     fprintf(ctx->fp, "\t.long %s\n", sym);
  45     break;
  46   }
  47 }
  48
  49 static const char *const jccnames[] = {
  50   "jo", "jno", "jb", "jnb", "jz", "jnz", "jbe", "ja",
  51   "js", "jns", "jpe", "jpo", "jl", "jge", "jle", "jg"
  52 };
  53
  54 /* Emit relocation for the incredibly stupid OSX assembler. */
  55 static void emit_asm_reloc_mach(BuildCtx *ctx, uint8_t *cp, int n,
  56                                 const char *sym)
  57 {
  58   const char *opname = NULL;
  59   if (--n < 0) goto err;
  60   if (cp[n] == 0xe8) {
  61     opname = "call";
  62   } else if (cp[n] == 0xe9) {
  63     opname = "jmp";
  64   } else if (cp[n] >= 0x80 && cp[n] <= 0x8f && n > 0 && cp[n-1] == 0x0f) {
  65     opname = jccnames[cp[n]-0x80];
  66     n--;
  67   } else {
  68 err:
  69     fprintf(stderr, "Error: unsupported opcode for %s symbol relocation.\n",
  70             sym);
  71     exit(1);
  72   }
  73   emit_asm_bytes(ctx, cp, n);
  74   fprintf(ctx->fp, "\t%s %s\n", opname, sym);
  75 }
  76 #else
  77 /* Emit words piecewise as assembler text. */
  78 static void emit_asm_words(BuildCtx *ctx, uint8_t *p, int n)
  79 {
  80   int i;
  81   for (i = 0; i < n; i += 4) {
  82     if ((i & 15) == 0)
  83       fprintf(ctx->fp, "\t.long 0x%08x", *(uint32_t *)(p+i));
  84     else
  85       fprintf(ctx->fp, ",0x%08x", *(uint32_t *)(p+i));
  86     if ((i & 15) == 12) putc('\n', ctx->fp);
  87   }
  88   if ((n & 15) != 0) putc('\n', ctx->fp);
  89 }
  90
  91 /* Emit relocation as part of an instruction. */
  92 static void emit_asm_wordreloc(BuildCtx *ctx, uint8_t *p, int n,
  93                                const char *sym)
  94 {
  95   uint32_t ins;
  96   emit_asm_words(ctx, p, n-4);
  97   ins = *(uint32_t *)(p+n-4);
  98 #if LJ_TARGET_ARM
  99   if ((ins & 0xff000000u) == 0xfa000000u) {
 100     fprintf(ctx->fp, "\tblx %s\n", sym);
 101   } else if ((ins & 0x0e000000u) == 0x0a000000u) {
 102     fprintf(ctx->fp, "\t%s%.2s %s\n", (ins & 0x01000000u) ? "bl" : "b",
 103             "eqnecsccmiplvsvchilsgeltgtle" + 2*(ins >> 28), sym);
 104   } else {
 105     fprintf(stderr,
 106             "Error: unsupported opcode %08x for %s symbol relocation.\n",
 107             ins, sym);
 108     exit(1);
 109   }
 110 #elif LJ_TARGET_PPC || LJ_TARGET_PPCSPE
 111   if ((ins >> 26) == 16) {
 112     fprintf(ctx->fp, "\t%s %d, %d, %s\n",
 113             (ins & 1) ? "bcl" : "bc", (ins >> 21) & 31, (ins >> 16) & 31, sym);
 114   } else if ((ins >> 26) == 18) {
 115     fprintf(ctx->fp, "\t%s %s\n", (ins & 1) ? "bl" : "b", sym);
 116   } else {
 117     fprintf(stderr,
 118             "Error: unsupported opcode %08x for %s symbol relocation.\n",
 119             ins, sym);
 120     exit(1);
 121   }
 122 #elif LJ_TARGET_MIPS
 123   fprintf(stderr,
 124           "Error: unsupported opcode %08x for %s symbol relocation.\n",
 125           ins, sym);
 126   exit(1);
 127 #else
 128 #error "missing relocation support for this architecture"
 129 #endif
 130 }
 131 #endif
 132
 133 #if LJ_TARGET_ARM
 134 #define ELFASM_PX       "%%"
 135 #else
 136 #define ELFASM_PX       "@"
 137 #endif
 138
 139 /* Emit an assembler label. */
 140 static void emit_asm_label(BuildCtx *ctx, const char *name, int size, int isfunc)
 141 {
 142   switch (ctx->mode) {
 143   case BUILD_elfasm:
 144     fprintf(ctx->fp,
 145       "\n\t.globl %s\n"
 146       "\t.hidden %s\n"
 147       "\t.type %s, " ELFASM_PX "%s\n"
 148       "\t.size %s, %d\n"
 149       "%s:\n",
 150       name, name, name, isfunc ? "function" : "object", name, size, name);
 151     break;
 152   case BUILD_coffasm:
 153     fprintf(ctx->fp, "\n\t.globl %s\n", name);
 154     if (isfunc)
 155       fprintf(ctx->fp, "\t.def %s; .scl 3; .type 32; .endef\n", name);
 156     fprintf(ctx->fp, "%s:\n", name);
 157     break;
 158   case BUILD_machasm:
 159     fprintf(ctx->fp,
 160       "\n\t.private_extern %s\n"
 161       "%s:\n", name, name);
 162     break;
 163   default:
 164     break;
 165   }
 166 }
 167
 168 /* Emit alignment. */
 169 static void emit_asm_align(BuildCtx *ctx, int bits)
 170 {
 171   switch (ctx->mode) {
 172   case BUILD_elfasm:
 173   case BUILD_coffasm:
 174     fprintf(ctx->fp, "\t.p2align %d\n", bits);
 175     break;
 176   case BUILD_machasm:
 177     fprintf(ctx->fp, "\t.align %d\n", bits);
 178     break;
 179   default:
 180     break;
 181   }
 182 }
 183
 184 /* ------------------------------------------------------------------------ */
 185
 186 /* Emit assembler source code. */
 187 void emit_asm(BuildCtx *ctx)
 188 {
 189   int i, rel;
 190
 191   fprintf(ctx->fp, "\t.file \"buildvm_%s.dasc\"\n", ctx->dasm_arch);
 192   fprintf(ctx->fp, "\t.text\n");
 193   emit_asm_align(ctx, 4);
 194
 195   emit_asm_label(ctx, ctx->beginsym, 0, 0);
 196   if (ctx->mode != BUILD_machasm)
 197     fprintf(ctx->fp, ".Lbegin:\n");
 198
 199 #if LJ_TARGET_ARM && defined(__GNUC__) && !defined(LUAJIT_NO_UNWIND)
 200   /* This should really be moved into buildvm_arm.dasc. */
 201   fprintf(ctx->fp,
 202           ".fnstart\n"
 203           ".save {r4, r5, r6, r7, r8, r9, r10, r11, lr}\n"
 204           ".pad #28\n");
 205 #endif
 206 #if LJ_TARGET_MIPS
 207   fprintf(ctx->fp, ".set nomips16\n.abicalls\n.set noreorder\n.set nomacro\n");
 208 #endif
 209
 210   for (i = rel = 0; i < ctx->nsym; i++) {
 211     int32_t ofs = ctx->sym[i].ofs;
 212     int32_t next = ctx->sym[i+1].ofs;
 213 #if LJ_TARGET_ARM && defined(__GNUC__) && !defined(LUAJIT_NO_UNWIND) && \
 214     LJ_HASFFI
 215     if (!strcmp(ctx->sym[i].name, "lj_vm_ffi_call"))
 216       fprintf(ctx->fp,
 217               ".globl lj_err_unwind_arm\n"
 218               ".personality lj_err_unwind_arm\n"
 219               ".fnend\n"
 220               ".fnstart\n"
 221               ".save {r4, r5, r11, lr}\n"
 222               ".setfp r11, sp\n");
 223 #endif
 224     emit_asm_label(ctx, ctx->sym[i].name, next - ofs, 1);
 225     while (rel < ctx->nreloc && ctx->reloc[rel].ofs <= next) {
 226       BuildReloc *r = &ctx->reloc[rel];
 227       int n = r->ofs - ofs;
 228 #if LJ_TARGET_X86ORX64
 229       if (ctx->mode == BUILD_machasm && r->type != 0) {
 230         emit_asm_reloc_mach(ctx, ctx->code+ofs, n, ctx->relocsym[r->sym]);
 231       } else {
 232         emit_asm_bytes(ctx, ctx->code+ofs, n);
 233         emit_asm_reloc(ctx, r->type, ctx->relocsym[r->sym]);
 234       }
 235       ofs += n+4;
 236 #else
 237       emit_asm_wordreloc(ctx, ctx->code+ofs, n, ctx->relocsym[r->sym]);
 238       ofs += n;
 239 #endif
 240       rel++;
 241     }
 242 #if LJ_TARGET_X86ORX64
 243     emit_asm_bytes(ctx, ctx->code+ofs, next-ofs);
 244 #else
 245     emit_asm_words(ctx, ctx->code+ofs, next-ofs);
 246 #endif
 247   }
 248
 249 #if LJ_TARGET_ARM && defined(__GNUC__) && !defined(LUAJIT_NO_UNWIND)
 250   fprintf(ctx->fp,
 251 #if !LJ_HASFFI
 252           ".globl lj_err_unwind_arm\n"
 253           ".personality lj_err_unwind_arm\n"
 254 #endif
 255           ".fnend\n");
 256 #endif
 257
 258   fprintf(ctx->fp, "\n");
 259   switch (ctx->mode) {
 260   case BUILD_elfasm:
 261     fprintf(ctx->fp, "\t.section .note.GNU-stack,\"\"," ELFASM_PX "progbits\n");
 262 #if LJ_TARGET_PPCSPE
 263     /* Soft-float ABI + SPE. */
 264     fprintf(ctx->fp, "\t.gnu_attribute 4, 2\n\t.gnu_attribute 8, 3\n");
 265 #elif LJ_TARGET_PPC
 266     /* Hard-float ABI. */
 267     fprintf(ctx->fp, "\t.gnu_attribute 4, 1\n");
 268 #endif
 269     /* fallthrough */
 270   case BUILD_coffasm:
 271     fprintf(ctx->fp, "\t.ident \"%s\"\n", ctx->dasm_ident);
 272     break;
 273   case BUILD_machasm:
 274     fprintf(ctx->fp,
 275       "\t.cstring\n"
 276       "\t.ascii \"%s\\0\"\n", ctx->dasm_ident);
 277     break;
 278   default:
 279     break;
 280   }
 281   fprintf(ctx->fp, "\n");
 282 }
 283