Tidy jump handling code and comments.

diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index c2d894ba349e29849db5a3a8f5ff64975181162b..197387aaadb2a688eaffe0077da8e479107aa538 100644 (file)
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -236,8 +236,8 @@ static char stackop_size = '\0';  /* Used in 16 bit gcc mode to add an l
 
 /* Interface to relax_segment.
    There are 2 relax states for 386 jump insns: one for conditional &
-   one for unconditional jumps.  This is because the these two types
-   of jumps add different sizes to frags when we're figuring out what
+   one for unconditional jumps.  This is because these two types of
+   jumps add different sizes to frags when we're figuring out what
    sort of jump to choose to reach a given label.  */
 
 /* types */
@@ -2092,23 +2092,33 @@ md_assemble (line)
     /* Output jumps. */
     if (i.tm.opcode_modifier & Jump)
       {
-       long n = (long) i.disps[0]->X_add_number;
-       int prefix = (i.prefix[DATA_PREFIX] != 0);
-       int code16 = 0;
+       int size;
+       int code16;
+       int prefix;
 
-       if (prefix)
+       code16 = 0;
+       if (flag_16bit_code)
+         code16 = CODE16;
+
+       prefix = 0;
+       if (i.prefix[DATA_PREFIX])
          {
+           prefix = 1;
            i.prefixes -= 1;
-           code16 = CODE16;
+           code16 ^= CODE16;
          }
-       if (flag_16bit_code)
-         code16 ^= CODE16;
 
-       if (!intel_syntax && (i.prefixes != 0))
+       size = 4;
+       if (code16)
+         size = 2;
+
+       if (i.prefixes != 0 && !intel_syntax)
          as_warn (_("skipping prefixes on this instruction"));
 
        if (i.disps[0]->X_op == O_constant)
          {
+           long n = (long) i.disps[0]->X_add_number;
+
            if (fits_in_signed_byte (n))
              {
                insn_size += 2;
@@ -2122,7 +2132,6 @@ md_assemble (line)
                   because text segments are limited to 64K anyway;
                   Use 32-bit jumps for 32-bit code, because they're faster,
                   and a 16-bit jump will clear the top 16 bits of %eip.  */
-               int jmp_size = code16 ? 2 : 4;
                if (code16 && !fits_in_signed_word (n))
                  {
                    as_bad (_("16-bit jump out of range"));
@@ -2132,56 +2141,60 @@ md_assemble (line)
                if (i.tm.base_opcode == JUMP_PC_RELATIVE)
                  {             /* pace */
                    /* unconditional jump */
-                   insn_size += prefix + 1 + jmp_size;
-                   p = frag_more (prefix + 1 + jmp_size);
+                   insn_size += prefix + 1 + size;
+                   p = frag_more (prefix + 1 + size);
                    if (prefix)
                      *p++ = DATA_PREFIX_OPCODE;
                    *p++ = (char) 0xe9;
-                   md_number_to_chars (p, (valueT) n, jmp_size);
+                   md_number_to_chars (p, (valueT) n, size);
                  }
                else
                  {
                    /* conditional jump */
-                   insn_size += prefix + 2 + jmp_size;
-                   p = frag_more (prefix + 2 + jmp_size);
+                   insn_size += prefix + 2 + size;
+                   p = frag_more (prefix + 2 + size);
                    if (prefix)
                      *p++ = DATA_PREFIX_OPCODE;
                    *p++ = TWO_BYTE_OPCODE_ESCAPE;
                    *p++ = i.tm.base_opcode + 0x10;
-                   md_number_to_chars (p, (valueT) n, jmp_size);
+                   md_number_to_chars (p, (valueT) n, size);
                  }
              }
          }
        else
          {
-           int size = code16 ? 2 : 4;
-
-           /* It's a symbol; end frag & setup for relax.
-              Make sure there are more than 6 chars left in the current frag;
-              if not we'll have to start a new one. */
-           frag_grow (prefix + 1 + 2 + size);
-           insn_size += 1 + prefix;
-           p = frag_more (1 + prefix);
+           /* It's a symbol;  End frag & setup for relax.
+              Make sure there is enough room in this frag for the largest
+              instruction we may generate in md_convert_frag.  This is 2
+              bytes for the opcode and room for the prefix and largest
+              displacement.  */
+           frag_grow (prefix + 2 + size);
+           insn_size += prefix + 1;
+           /* Prefix and 1 opcode byte go in fr_fix.  */
+           p = frag_more (prefix + 1);
            if (prefix)
              *p++ = DATA_PREFIX_OPCODE;
            *p = i.tm.base_opcode;
+           /* 1 possible extra opcode + displacement go in fr_var */
            frag_var (rs_machine_dependent,
-                     prefix + 2 + size, /* 2 opcode/prefix + displacement */
+                     1 + size,
                      1,
                      ((unsigned char) *p == JUMP_PC_RELATIVE
                       ? ENCODE_RELAX_STATE (UNCOND_JUMP, SMALL) | code16
                       : ENCODE_RELAX_STATE (COND_JUMP, SMALL) | code16),
                      i.disps[0]->X_add_symbol,
-                     (offsetT) n, p);
+                     i.disps[0]->X_add_number,
+                     p);
          }
       }
     else if (i.tm.opcode_modifier & (JumpByte | JumpDword))
       {
-       int size = (i.tm.opcode_modifier & JumpByte) ? 1 : 4;
-       long n = (long) i.disps[0]->X_add_number;
+       int size;
 
-       if (size == 1) /* then this is a loop or jecxz type instruction */
+       if (i.tm.opcode_modifier & JumpByte)
          {
+           /* This is a loop or jecxz type instruction.  */
+           size = 1;
            if (i.prefix[ADDR_PREFIX])
              {
                insn_size += 1;
@@ -2191,23 +2204,26 @@ md_assemble (line)
          }
        else
          {
-           int code16 = 0;
+           int code16;
+
+           code16 = 0;
+           if (flag_16bit_code)
+             code16 = CODE16;
 
            if (i.prefix[DATA_PREFIX])
              {
                insn_size += 1;
                FRAG_APPEND_1_CHAR (DATA_PREFIX_OPCODE);
                i.prefixes -= 1;
-               code16 = CODE16;
+               code16 ^= CODE16;
              }
-           if (flag_16bit_code)
-             code16 ^= CODE16;
 
+           size = 4;
            if (code16)
              size = 2;
          }
 
-       if (!intel_syntax && (i.prefixes != 0))
+       if (i.prefixes != 0 && !intel_syntax)
          as_warn (_("skipping prefixes on this instruction"));
 
        if (fits_in_unsigned_byte (i.tm.base_opcode))
@@ -2217,7 +2233,8 @@ md_assemble (line)
          }
        else
          {
-           insn_size += 2 + size;      /* opcode can be at most two bytes */
+           /* opcode can be at most two bytes */
+           insn_size += 2 + size;
            p = frag_more (2 + size);
            *p++ = (i.tm.base_opcode >> 8) & 0xff;
          }
@@ -2225,6 +2242,8 @@ md_assemble (line)
 
        if (i.disps[0]->X_op == O_constant)
          {
+           long n = (long) i.disps[0]->X_add_number;
+
            if (size == 1 && !fits_in_signed_byte (n))
              {
                as_bad (_("`%s' only takes byte displacement; %ld shortened to %d"),
@@ -2248,16 +2267,20 @@ md_assemble (line)
       {
        int size;
        int reloc_type;
-       int prefix = i.prefix[DATA_PREFIX] != 0;
-       int code16 = 0;
+       int prefix;
+       int code16;
 
-       if (prefix)
+       code16 = 0;
+       if (flag_16bit_code)
+         code16 = CODE16;
+
+       prefix = 0;
+       if (i.prefix[DATA_PREFIX])
          {
-           code16 = CODE16;
+           prefix = 1;
            i.prefixes -= 1;
+           code16 ^= CODE16;
          }
-       if (flag_16bit_code)
-         code16 ^= CODE16;
 
        size = 4;
        reloc_type = BFD_RELOC_32;
@@ -2267,7 +2290,7 @@ md_assemble (line)
            reloc_type = BFD_RELOC_16;
          }
 
-       if (!intel_syntax && (i.prefixes != 0))
+       if (i.prefixes != 0 && !intel_syntax)
          as_warn (_("skipping prefixes on this instruction"));
 
        insn_size += prefix + 1 + 2 + size;  /* 1 opcode; 2 segment; offset */
@@ -4235,7 +4258,6 @@ i386_target_format ()
 #endif /* OBJ_MAYBE_ELF */
 #endif /* BFD_ASSEMBLER */
 \f
-/* ARGSUSED */
 symbolS *
 md_undefined_symbol (name)
      char *name;