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
 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 #else
 123 #error "missing relocation support for this architecture"
 124 #endif
 125 }
 126 #endif
 127
 128 #if LJ_TARGET_ARM
 129 #define ELFASM_PX       "%%"
 130 #else
 131 #define ELFASM_PX       "@"
 132 #endif
 133
 134 /* Emit an assembler label. */
 135 static void emit_asm_label(BuildCtx *ctx, const char *name, int size, int isfunc)
 136 {
 137   switch (ctx->mode) {
 138   case BUILD_elfasm:
 139     fprintf(ctx->fp,
 140       "\n\t.globl %s\n"
 141       "\t.hidden %s\n"
 142       "\t.type %s, " ELFASM_PX "%s\n"
 143       "\t.size %s, %d\n"
 144       "%s:\n",
 145       name, name, name, isfunc ? "function" : "object", name, size, name);
 146     break;
 147   case BUILD_coffasm:
 148     fprintf(ctx->fp, "\n\t.globl %s\n", name);
 149     if (isfunc)
 150       fprintf(ctx->fp, "\t.def %s; .scl 3; .type 32; .endef\n", name);
 151     fprintf(ctx->fp, "%s:\n", name);
 152     break;
 153   case BUILD_machasm:
 154     fprintf(ctx->fp,
 155       "\n\t.private_extern %s\n"
 156       "%s:\n", name, name);
 157     break;
 158   default:
 159     break;
 160   }
 161 }
 162
 163 /* Emit alignment. */
 164 static void emit_asm_align(BuildCtx *ctx, int bits)
 165 {
 166   switch (ctx->mode) {
 167   case BUILD_elfasm:
 168   case BUILD_coffasm:
 169     fprintf(ctx->fp, "\t.p2align %d\n", bits);
 170     break;
 171   case BUILD_machasm:
 172     fprintf(ctx->fp, "\t.align %d\n", bits);
 173     break;
 174   default:
 175     break;
 176   }
 177 }
 178
 179 /* ------------------------------------------------------------------------ */
 180
 181 /* Emit assembler source code. */
 182 void emit_asm(BuildCtx *ctx)
 183 {
 184   int i, rel;
 185
 186   fprintf(ctx->fp, "\t.file \"buildvm_%s.dasc\"\n", ctx->dasm_arch);
 187   fprintf(ctx->fp, "\t.text\n");
 188   emit_asm_align(ctx, 4);
 189
 190   emit_asm_label(ctx, ctx->beginsym, 0, 0);
 191   if (ctx->mode != BUILD_machasm)
 192     fprintf(ctx->fp, ".Lbegin:\n");
 193
 194   for (i = rel = 0; i < ctx->nsym; i++) {
 195     int32_t ofs = ctx->sym[i].ofs;
 196     int32_t next = ctx->sym[i+1].ofs;
 197     emit_asm_label(ctx, ctx->sym[i].name, next - ofs, 1);
 198     while (rel < ctx->nreloc && ctx->reloc[rel].ofs <= next) {
 199       BuildReloc *r = &ctx->reloc[rel];
 200       int n = r->ofs - ofs;
 201 #if LJ_TARGET_X86ORX64
 202       if (ctx->mode == BUILD_machasm && r->type != 0) {
 203         emit_asm_reloc_mach(ctx, ctx->code+ofs, n, ctx->relocsym[r->sym]);
 204       } else {
 205         emit_asm_bytes(ctx, ctx->code+ofs, n);
 206         emit_asm_reloc(ctx, r->type, ctx->relocsym[r->sym]);
 207       }
 208       ofs += n+4;
 209 #else
 210       emit_asm_wordreloc(ctx, ctx->code+ofs, n, ctx->relocsym[r->sym]);
 211       ofs += n;
 212 #endif
 213       rel++;
 214     }
 215 #if LJ_TARGET_X86ORX64
 216     emit_asm_bytes(ctx, ctx->code+ofs, next-ofs);
 217 #else
 218     emit_asm_words(ctx, ctx->code+ofs, next-ofs);
 219 #endif
 220   }
 221
 222   fprintf(ctx->fp, "\n");
 223   switch (ctx->mode) {
 224   case BUILD_elfasm:
 225     fprintf(ctx->fp, "\t.section .note.GNU-stack,\"\"," ELFASM_PX "progbits\n");
 226 #if LJ_TARGET_PPCSPE
 227     /* Soft-float ABI + SPE. */
 228     fprintf(ctx->fp, "\t.gnu_attribute 4, 2\n\t.gnu_attribute 8, 3\n");
 229 #elif LJ_TARGET_PPC
 230     /* Hard-float ABI. */
 231     fprintf(ctx->fp, "\t.gnu_attribute 4, 1\n");
 232 #endif
 233     /* fallthrough */
 234   case BUILD_coffasm:
 235     fprintf(ctx->fp, "\t.ident \"%s\"\n", ctx->dasm_ident);
 236     break;
 237   case BUILD_machasm:
 238     fprintf(ctx->fp,
 239       "\t.cstring\n"
 240       "\t.ascii \"%s\\0\"\n", ctx->dasm_ident);
 241     break;
 242   default:
 243     break;
 244   }
 245   fprintf(ctx->fp, "\n");
 246 }
 247