src/buildvm_asm.c

   1 /*
   2 ** LuaJIT VM builder: Assembler source code emitter.
   3 ** Copyright (C) 2005-2011 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   UNUSED(sym);  /* NYI */
 124 #else
 125 #error "missing relocation support for this architecture"
 126 #endif
 127 }
 128 #endif
 129
 130 #if LJ_TARGET_ARM
 131 #define ELFASM_PX       "%%"
 132 #else
 133 #define ELFASM_PX       "@"
 134 #endif
 135
 136 /* Emit an assembler label. */
 137 static void emit_asm_label(BuildCtx *ctx, const char *name, int size, int isfunc)
 138 {
 139   switch (ctx->mode) {
 140   case BUILD_elfasm:
 141     fprintf(ctx->fp,
 142       "\n\t.globl %s\n"
 143       "\t.hidden %s\n"
 144       "\t.type %s, " ELFASM_PX "%s\n"
 145       "\t.size %s, %d\n"
 146       "%s:\n",
 147       name, name, name, isfunc ? "function" : "object", name, size, name);
 148     break;
 149   case BUILD_coffasm:
 150     fprintf(ctx->fp, "\n\t.globl %s\n", name);
 151     if (isfunc)
 152       fprintf(ctx->fp, "\t.def %s; .scl 3; .type 32; .endef\n", name);
 153     fprintf(ctx->fp, "%s:\n", name);
 154     break;
 155   case BUILD_machasm:
 156     fprintf(ctx->fp,
 157       "\n\t.private_extern %s\n"
 158       "%s:\n", name, name);
 159     break;
 160   default:
 161     break;
 162   }
 163 }
 164
 165 /* Emit alignment. */
 166 static void emit_asm_align(BuildCtx *ctx, int bits)
 167 {
 168   switch (ctx->mode) {
 169   case BUILD_elfasm:
 170   case BUILD_coffasm:
 171     fprintf(ctx->fp, "\t.p2align %d\n", bits);
 172     break;
 173   case BUILD_machasm:
 174     fprintf(ctx->fp, "\t.align %d\n", bits);
 175     break;
 176   default:
 177     break;
 178   }
 179 }
 180
 181 /* ------------------------------------------------------------------------ */
 182
 183 /* Emit assembler source code. */
 184 void emit_asm(BuildCtx *ctx)
 185 {
 186   int i, rel;
 187
 188   fprintf(ctx->fp, "\t.file \"buildvm_%s.dasc\"\n", ctx->dasm_arch);
 189   fprintf(ctx->fp, "\t.text\n");
 190   emit_asm_align(ctx, 4);
 191
 192   emit_asm_label(ctx, ctx->beginsym, 0, 0);
 193   if (ctx->mode != BUILD_machasm)
 194     fprintf(ctx->fp, ".Lbegin:\n");
 195
 196 #if LJ_TARGET_ARM && defined(__GNUC__) && !defined(LUAJIT_NO_UNWIND)
 197   /* This should really be moved into buildvm_arm.dasc. */
 198   fprintf(ctx->fp,
 199           ".fnstart\n"
 200           ".save {r4, r5, r6, r7, r8, r9, r10, r11, lr}\n"
 201           ".pad #28\n");
 202 #endif
 203
 204   for (i = rel = 0; i < ctx->nsym; i++) {
 205     int32_t ofs = ctx->sym[i].ofs;
 206     int32_t next = ctx->sym[i+1].ofs;
 207 #if LJ_TARGET_ARM && defined(__GNUC__) && !defined(LUAJIT_NO_UNWIND) && \
 208     LJ_HASFFI
 209     if (!strcmp(ctx->sym[i].name, "lj_vm_ffi_call"))
 210       fprintf(ctx->fp,
 211               ".globl lj_err_unwind_arm\n"
 212               ".personality lj_err_unwind_arm\n"
 213               ".fnend\n"
 214               ".fnstart\n"
 215               ".save {r4, r5, r11, lr}\n"
 216               ".setfp r11, sp\n");
 217 #endif
 218     emit_asm_label(ctx, ctx->sym[i].name, next - ofs, 1);
 219     while (rel < ctx->nreloc && ctx->reloc[rel].ofs <= next) {
 220       BuildReloc *r = &ctx->reloc[rel];
 221       int n = r->ofs - ofs;
 222 #if LJ_TARGET_X86ORX64
 223       if (ctx->mode == BUILD_machasm && r->type != 0) {
 224         emit_asm_reloc_mach(ctx, ctx->code+ofs, n, ctx->relocsym[r->sym]);
 225       } else {
 226         emit_asm_bytes(ctx, ctx->code+ofs, n);
 227         emit_asm_reloc(ctx, r->type, ctx->relocsym[r->sym]);
 228       }
 229       ofs += n+4;
 230 #else
 231       emit_asm_wordreloc(ctx, ctx->code+ofs, n, ctx->relocsym[r->sym]);
 232       ofs += n;
 233 #endif
 234       rel++;
 235     }
 236 #if LJ_TARGET_X86ORX64
 237     emit_asm_bytes(ctx, ctx->code+ofs, next-ofs);
 238 #else
 239     emit_asm_words(ctx, ctx->code+ofs, next-ofs);
 240 #endif
 241   }
 242
 243 #if LJ_TARGET_ARM && defined(__GNUC__) && !defined(LUAJIT_NO_UNWIND)
 244   fprintf(ctx->fp,
 245 #if !LJ_HASFFI
 246           ".globl lj_err_unwind_arm\n"
 247           ".personality lj_err_unwind_arm\n"
 248 #endif
 249           ".fnend\n");
 250 #endif
 251
 252   fprintf(ctx->fp, "\n");
 253   switch (ctx->mode) {
 254   case BUILD_elfasm:
 255     fprintf(ctx->fp, "\t.section .note.GNU-stack,\"\"," ELFASM_PX "progbits\n");
 256 #if LJ_TARGET_PPCSPE
 257     /* Soft-float ABI + SPE. */
 258     fprintf(ctx->fp, "\t.gnu_attribute 4, 2\n\t.gnu_attribute 8, 3\n");
 259 #elif LJ_TARGET_PPC
 260     /* Hard-float ABI. */
 261     fprintf(ctx->fp, "\t.gnu_attribute 4, 1\n");
 262 #endif
 263     /* fallthrough */
 264   case BUILD_coffasm:
 265     fprintf(ctx->fp, "\t.ident \"%s\"\n", ctx->dasm_ident);
 266     break;
 267   case BUILD_machasm:
 268     fprintf(ctx->fp,
 269       "\t.cstring\n"
 270       "\t.ascii \"%s\\0\"\n", ctx->dasm_ident);
 271     break;
 272   default:
 273     break;
 274   }
 275   fprintf(ctx->fp, "\n");
 276 }
 277