x86: embed register and alike names in disassembler

Register names are (including their nul terminators) on average almost 4
bytes long. Otoh no register name is longer than 8 bytes. Hence even for
32-bit builds using a pointer is only slightly more space efficient than
embedding the strings. A level of indirection can be also avoided by
embedding the names as an array of 8 characters directly in the arrays,
and the number of base relocations in libopcodes.so (or PIE builds of
statically linked executables) goes down as well.

To amortize for the otherwise reduced folding of string literals by the
linker, use att_names_seg[] in place of string literals in append_seg()
and OP_ESreg().

diff --git a/opcodes/i386-dis.c b/opcodes/i386-dis.c
index 1c44e099eb2bed521de0499fce7cc488c16552b7..a414e8c9b1ef8aa2334406120d33993c61b001c7 100644 (file)
--- a/opcodes/i386-dis.c
+++ b/opcodes/i386-dis.c
@@ -2462,48 +2462,48 @@ struct op
    need to update onebyte_has_modrm or twobyte_has_modrm.  */
 #define MODRM_CHECK  if (!ins->need_modrm) abort ()
 
-static const char *const intel_index16[] = {
+static const char intel_index16[][6] = {
   "bx+si", "bx+di", "bp+si", "bp+di", "si", "di", "bp", "bx"
 };
 
-static const char *const att_names64[] = {
+static const char att_names64[][8] = {
   "%rax", "%rcx", "%rdx", "%rbx", "%rsp", "%rbp", "%rsi", "%rdi",
   "%r8", "%r9", "%r10", "%r11", "%r12", "%r13", "%r14", "%r15"
 };
-static const char *const att_names32[] = {
+static const char att_names32[][8] = {
   "%eax", "%ecx", "%edx", "%ebx", "%esp", "%ebp", "%esi", "%edi",
   "%r8d", "%r9d", "%r10d", "%r11d", "%r12d", "%r13d", "%r14d", "%r15d"
 };
-static const char *const att_names16[] = {
+static const char att_names16[][8] = {
   "%ax", "%cx", "%dx", "%bx", "%sp", "%bp", "%si", "%di",
   "%r8w", "%r9w", "%r10w", "%r11w", "%r12w", "%r13w", "%r14w", "%r15w"
 };
-static const char *const att_names8[] = {
+static const char att_names8[][8] = {
   "%al", "%cl", "%dl", "%bl", "%ah", "%ch", "%dh", "%bh",
 };
-static const char *const att_names8rex[] = {
+static const char att_names8rex[][8] = {
   "%al", "%cl", "%dl", "%bl", "%spl", "%bpl", "%sil", "%dil",
   "%r8b", "%r9b", "%r10b", "%r11b", "%r12b", "%r13b", "%r14b", "%r15b"
 };
-static const char *const att_names_seg[] = {
+static const char att_names_seg[][4] = {
   "%es", "%cs", "%ss", "%ds", "%fs", "%gs", "%?", "%?",
 };
 static const char att_index64[] = "%riz";
 static const char att_index32[] = "%eiz";
-static const char *const att_index16[] = {
+static const char att_index16[][8] = {
   "%bx,%si", "%bx,%di", "%bp,%si", "%bp,%di", "%si", "%di", "%bp", "%bx"
 };
 
-static const char *const att_names_mm[] = {
+static const char att_names_mm[][8] = {
   "%mm0", "%mm1", "%mm2", "%mm3",
   "%mm4", "%mm5", "%mm6", "%mm7"
 };
 
-static const char *const att_names_bnd[] = {
+static const char att_names_bnd[][8] = {
   "%bnd0", "%bnd1", "%bnd2", "%bnd3"
 };
 
-static const char *const att_names_xmm[] = {
+static const char att_names_xmm[][8] = {
   "%xmm0", "%xmm1", "%xmm2", "%xmm3",
   "%xmm4", "%xmm5", "%xmm6", "%xmm7",
   "%xmm8", "%xmm9", "%xmm10", "%xmm11",
@@ -2514,7 +2514,7 @@ static const char *const att_names_xmm[] = {
   "%xmm28", "%xmm29", "%xmm30", "%xmm31"
 };
 
-static const char *const att_names_ymm[] = {
+static const char att_names_ymm[][8] = {
   "%ymm0", "%ymm1", "%ymm2", "%ymm3",
   "%ymm4", "%ymm5", "%ymm6", "%ymm7",
   "%ymm8", "%ymm9", "%ymm10", "%ymm11",
@@ -2525,7 +2525,7 @@ static const char *const att_names_ymm[] = {
   "%ymm28", "%ymm29", "%ymm30", "%ymm31"
 };
 
-static const char *const att_names_zmm[] = {
+static const char att_names_zmm[][8] = {
   "%zmm0", "%zmm1", "%zmm2", "%zmm3",
   "%zmm4", "%zmm5", "%zmm6", "%zmm7",
   "%zmm8", "%zmm9", "%zmm10", "%zmm11",
@@ -2536,12 +2536,12 @@ static const char *const att_names_zmm[] = {
   "%zmm28", "%zmm29", "%zmm30", "%zmm31"
 };
 
-static const char *const att_names_tmm[] = {
+static const char att_names_tmm[][8] = {
   "%tmm0", "%tmm1", "%tmm2", "%tmm3",
   "%tmm4", "%tmm5", "%tmm6", "%tmm7"
 };
 
-static const char *const att_names_mask[] = {
+static const char att_names_mask[][8] = {
   "%k0", "%k1", "%k2", "%k3", "%k4", "%k5", "%k6", "%k7"
 };
 
@@ -11291,22 +11291,22 @@ append_seg (instr_info *ins)
   switch (ins->active_seg_prefix)
     {
     case PREFIX_CS:
-      oappend_register (ins, "%cs");
+      oappend_register (ins, att_names_seg[1]);
       break;
     case PREFIX_DS:
-      oappend_register (ins, "%ds");
+      oappend_register (ins, att_names_seg[3]);
       break;
     case PREFIX_SS:
-      oappend_register (ins, "%ss");
+      oappend_register (ins, att_names_seg[2]);
       break;
     case PREFIX_ES:
-      oappend_register (ins, "%es");
+      oappend_register (ins, att_names_seg[0]);
       break;
     case PREFIX_FS:
-      oappend_register (ins, "%fs");
+      oappend_register (ins, att_names_seg[4]);
       break;
     case PREFIX_GS:
-      oappend_register (ins, "%gs");
+      oappend_register (ins, att_names_seg[5]);
       break;
     default:
       break;
@@ -11649,7 +11649,7 @@ static void
 print_register (instr_info *ins, unsigned int reg, unsigned int rexmask,
                int bytemode, int sizeflag)
 {
-  const char *const *names;
+  const char (*names)[8];
 
   USED_REX (rexmask);
   if (ins->rex & rexmask)
@@ -11888,7 +11888,7 @@ OP_E_memory (instr_info *ins, int bytemode, int sizeflag)
                         || bytemode == bnd_mode
                         || bytemode == bnd_swap_mode);
       bool check_gather = false;
-      const char *const *indexes = NULL;
+      const char (*indexes)[8] = NULL;
 
       havebase = 1;
       base = ins->modrm.rm;
@@ -12177,8 +12177,8 @@ OP_E_memory (instr_info *ins, int bytemode, int sizeflag)
       if (ins->modrm.mod != 0 || ins->modrm.rm != 6)
        {
          oappend_char (ins, ins->open_char);
-         oappend (ins, (ins->intel_syntax ? intel_index16
-                        : att_index16)[ins->modrm.rm]);
+         oappend (ins, ins->intel_syntax ? intel_index16[ins->modrm.rm]
+                                         : att_index16[ins->modrm.rm]);
          if (ins->intel_syntax
              && (disp || ins->modrm.mod != 0 || ins->modrm.rm == 6))
            {
@@ -12801,7 +12801,7 @@ OP_ESreg (instr_info *ins, int code, int sizeflag)
          intel_operand_size (ins, b_mode, sizeflag);
        }
     }
-  oappend_register (ins, "%es");
+  oappend_register (ins, att_names_seg[0]);
   oappend_char (ins, ':');
   ptr_reg (ins, code, sizeflag);
 }
@@ -12898,7 +12898,7 @@ OP_MMX (instr_info *ins, int bytemode ATTRIBUTE_UNUSED,
        int sizeflag ATTRIBUTE_UNUSED)
 {
   int reg = ins->modrm.reg;
-  const char *const *names;
+  const char (*names)[8];
 
   ins->used_prefixes |= (ins->prefixes & PREFIX_DATA);
   if (ins->prefixes & PREFIX_DATA)
@@ -12916,7 +12916,7 @@ OP_MMX (instr_info *ins, int bytemode ATTRIBUTE_UNUSED,
 static void
 print_vector_reg (instr_info *ins, unsigned int reg, int bytemode)
 {
-  const char *const *names;
+  const char (*names)[8];
 
   if (bytemode == xmmq_mode
       || bytemode == evex_half_bcst_xmmqh_mode
@@ -13014,7 +13014,7 @@ static void
 OP_EM (instr_info *ins, int bytemode, int sizeflag)
 {
   int reg;
-  const char *const *names;
+  const char (*names)[8];
 
   if (ins->modrm.mod != 3)
     {
@@ -13370,8 +13370,8 @@ OP_Monitor (instr_info *ins, int bytemode ATTRIBUTE_UNUSED,
   /* monitor %{e,r,}ax,%ecx,%edx"  */
   if (!ins->intel_syntax)
     {
-      const char *const *names = (ins->address_mode == mode_64bit
-                                 ? att_names64 : att_names32);
+      const char (*names)[8] = (ins->address_mode == mode_64bit
+                               ? att_names64 : att_names32);
 
       if (ins->prefixes & PREFIX_ADDR)
        {
@@ -13547,7 +13547,7 @@ CMPXCHG8B_Fixup (instr_info *ins, int bytemode, int sizeflag)
 static void
 XMM_Fixup (instr_info *ins, int reg, int sizeflag ATTRIBUTE_UNUSED)
 {
-  const char *const *names = att_names_xmm;
+  const char (*names)[8] = att_names_xmm;
 
   if (ins->need_vex)
     {
@@ -13588,7 +13588,7 @@ static void
 OP_VEX (instr_info *ins, int bytemode, int sizeflag ATTRIBUTE_UNUSED)
 {
   int reg, modrm_reg, sib_index = -1;
-  const char *const *names;
+  const char (*names)[8];
 
   if (!ins->need_vex)
     abort ();
@@ -13763,7 +13763,7 @@ static void
 OP_REG_VexI4 (instr_info *ins, int bytemode, int sizeflag ATTRIBUTE_UNUSED)
 {
   int reg;
-  const char *const *names = att_names_xmm;
+  const char (*names)[8] = att_names_xmm;
 
   FETCH_DATA (ins->info, ins->codep + 1);
   reg = *ins->codep++;