Tweak comment.

1 files changed, 511 insertions, 0 deletions

diff --git a/gas/cgen.c b/gas/cgen.c
new file mode 100644
index 0000000..355268f
--- /dev/null
+++ b/gas/cgen.c
@@ -0,0 +1,511 @@
+/* GAS interface for targets using CGEN: Cpu tools GENerator.
+   Copyright (C) 1996, 1997 Free Software Foundation, Inc.
+
+This file is part of GAS, the GNU Assembler.
+
+GAS is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GAS is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GAS; see the file COPYING.  If not, write to the Free Software
+Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
+
+#include "ansidecl.h"
+#include "bfd.h"
+#include "cgen-opc.h"
+#include "as.h"
+#include "subsegs.h"
+
+/* Callback to insert a register into the symbol table.
+   A target may choose to let GAS parse the registers.
+   ??? Not currently used.  */
+
+void
+cgen_asm_record_register (name, number)
+     char *name;
+     int number;
+{
+  /* Use symbol_create here instead of symbol_new so we don't try to
+     output registers into the object file's symbol table.  */
+  symbol_table_insert (symbol_create (name, reg_section,
+				      number, &zero_address_frag));
+}
+
+/* We need to keep a list of fixups.  We can't simply generate them as
+   we go, because that would require us to first create the frag, and
+   that would screw up references to ``.''.
+
+   This is used by cpu's with simple operands.  It keeps knowledge of what
+   an `expressionS' is and what a `fixup' is out of CGEN which for the time
+   being is preferable.
+
+   OPINDEX is the index in the operand table.
+   OPINFO is something the caller chooses to help in reloc determination.  */
+
+struct fixup
+{
+  int opindex;
+  int opinfo;
+  expressionS exp;
+};
+
+#define MAX_FIXUPS 5
+
+static struct fixup fixups[MAX_FIXUPS];
+static int num_fixups;
+
+void
+cgen_asm_init_parse ()
+{
+  num_fixups = 0;
+}
+
+/* Queue a fixup.  */
+
+void
+cgen_queue_fixup (opindex, opinfo, expP)
+     int opindex;
+     expressionS *expP;
+{
+  /* We need to generate a fixup for this expression.  */
+  if (num_fixups >= MAX_FIXUPS)
+    as_fatal ("too many fixups");
+  fixups[num_fixups].exp = *expP;
+  fixups[num_fixups].opindex = opindex;
+  fixups[num_fixups].opinfo = opinfo;
+  ++num_fixups;
+}
+
+/* Default routine to record a fixup.
+   This is a cover function to fix_new.
+   It exists because we record INSN with the fixup.
+
+   FRAG and WHERE are their respective arguments to fix_new_exp.
+   LENGTH is in bits.
+   OPINFO is something the caller chooses to help in reloc determination.
+
+   At this point we do not use a bfd_reloc_code_real_type for
+   operands residing in the insn, but instead just use the
+   operand index.  This lets us easily handle fixups for any
+   operand type.  We pick a BFD reloc type in md_apply_fix.  */
+
+fixS *
+cgen_record_fixup (frag, where, insn, length, operand, opinfo, symbol, offset)
+     fragS *frag;
+     int where;
+     const struct cgen_insn *insn;
+     int length;
+     const struct cgen_operand *operand;
+     int opinfo;
+     symbolS *symbol;
+     offsetT offset;
+{
+  fixS *fixP;
+
+  /* It may seem strange to use operand->attrs and not insn->attrs here,
+     but it is the operand that has a pc relative relocation.  */
+
+  fixP = fix_new (frag, where, length / 8, symbol, offset,
+		  CGEN_OPERAND_ATTR (operand, CGEN_OPERAND_PCREL_ADDR) != 0,
+		  (bfd_reloc_code_real_type) ((int) BFD_RELOC_UNUSED + CGEN_OPERAND_INDEX (operand)));
+  fixP->tc_fix_data.insn = (PTR) insn;
+  fixP->tc_fix_data.opinfo = opinfo;
+
+  return fixP;
+}
+
+/* Default routine to record a fixup given an expression.
+   This is a cover function to fix_new_exp.
+   It exists because we record INSN with the fixup.
+
+   FRAG and WHERE are their respective arguments to fix_new_exp.
+   LENGTH is in bits.
+   OPINFO is something the caller chooses to help in reloc determination.
+
+   At this point we do not use a bfd_reloc_code_real_type for
+   operands residing in the insn, but instead just use the
+   operand index.  This lets us easily handle fixups for any
+   operand type.  We pick a BFD reloc type in md_apply_fix.  */
+
+fixS *
+cgen_record_fixup_exp (frag, where, insn, length, operand, opinfo, exp)
+     fragS *frag;
+     int where;
+     const struct cgen_insn *insn;
+     int length;
+     const struct cgen_operand *operand;
+     int opinfo;
+     expressionS *exp;
+{
+  fixS *fixP;
+
+  /* It may seem strange to use operand->attrs and not insn->attrs here,
+     but it is the operand that has a pc relative relocation.  */
+
+  fixP = fix_new_exp (frag, where, length / 8, exp,
+		      CGEN_OPERAND_ATTR (operand, CGEN_OPERAND_PCREL_ADDR) != 0,
+		      (bfd_reloc_code_real_type) ((int) BFD_RELOC_UNUSED + CGEN_OPERAND_INDEX (operand)));
+  fixP->tc_fix_data.insn = (PTR) insn;
+  fixP->tc_fix_data.opinfo = opinfo;
+
+  return fixP;
+}
+
+/* Callback for cgen interface.  Parse the expression at *STRP.
+   The result is an error message or NULL for success (in which case
+   *STRP is advanced past the parsed text).
+   An enum cgen_asm_result is stored in RESULTP.
+   OPINFO is something the caller chooses to help in reloc determination.
+   The resulting value is stored in VALUEP.  */
+
+const char *
+cgen_asm_parse_operand (strP, opindex, opinfo, resultP, valueP)
+     const char **strP;
+     int opindex;
+     int opinfo;
+     enum cgen_asm_result *resultP;
+     bfd_vma *valueP;
+{
+  char *hold;
+  const char *errmsg = NULL;
+  expressionS exp;
+
+  hold = input_line_pointer;
+  input_line_pointer = (char *) *strP;
+  expression (&exp);
+  *strP = input_line_pointer;
+  input_line_pointer = hold;
+
+  switch (exp.X_op)
+    {
+    case O_illegal :
+      errmsg = "illegal operand";
+      *resultP = CGEN_ASM_ERROR;
+      break;
+    case O_absent :
+      errmsg = "missing operand";
+      *resultP = CGEN_ASM_ERROR;
+      break;
+    case O_constant :
+      *valueP = exp.X_add_number;
+      *resultP = CGEN_ASM_NUMBER;
+      break;
+    case O_register :
+      *valueP = exp.X_add_number;
+      *resultP = CGEN_ASM_REGISTER;
+      break;
+    default :
+      cgen_queue_fixup (opindex, opinfo, &exp);
+      *valueP = 0;
+      *resultP = CGEN_ASM_QUEUED;
+      break;
+    }
+
+  return errmsg;
+}
+
+/* Finish assembling instruction INSN.
+   BUF contains what we've built up so far.
+   LENGTH is the size of the insn in bits.  */
+
+void
+cgen_asm_finish_insn (insn, buf, length)
+     const struct cgen_insn *insn;
+     cgen_insn_t *buf;
+     unsigned int length;
+{
+  int i, relax_operand;
+  char *f;
+  unsigned int byte_len = length / 8;
+
+  /* ??? Target foo issues various warnings here, so one might want to provide
+     a hook here.  However, our caller is defined in tc-foo.c so there
+     shouldn't be a need for a hook.  */
+
+  /* Write out the instruction.
+     It is important to fetch enough space in one call to `frag_more'.
+     We use (f - frag_now->fr_literal) to compute where we are and we
+     don't want frag_now to change between calls.
+
+     Relaxable instructions: We need to ensure we allocate enough
+     space for the largest insn.  */
+
+  if (CGEN_INSN_ATTR (insn, CGEN_INSN_RELAX) != 0)
+    abort (); /* These currently shouldn't get here.  */
+
+  /* Is there a relaxable insn with the relaxable operand needing a fixup?  */
+
+  relax_operand = -1;
+  if (CGEN_INSN_ATTR (insn, CGEN_INSN_RELAXABLE) != 0)
+    {
+      /* Scan the fixups for the operand affected by relaxing
+	 (i.e. the branch address).  */
+
+      for (i = 0; i < num_fixups; ++i)
+	{
+	  if (CGEN_OPERAND_ATTR (& CGEN_SYM (operand_table) [fixups[i].opindex],
+				 CGEN_OPERAND_RELAX) != 0)
+	    {
+	      relax_operand = i;
+	      break;
+	    }
+	}
+    }
+
+  if (relax_operand != -1)
+    {
+      int max_len;
+      fragS *old_frag;
+
+#ifdef TC_CGEN_MAX_RELAX
+      max_len = TC_CGEN_MAX_RELAX (insn, byte_len);
+#else
+      max_len = CGEN_MAX_INSN_SIZE;
+#endif
+      /* Ensure variable part and fixed part are in same fragment.  */
+      /* FIXME: Having to do this seems like a hack.  */
+      frag_grow (max_len);
+      /* Allocate space for the fixed part.  */
+      f = frag_more (byte_len);
+      /* Create a relaxable fragment for this instruction.  */
+      old_frag = frag_now;
+      frag_var (rs_machine_dependent,
+		max_len - byte_len /* max chars */,
+		0 /* variable part already allocated */,
+		/* FIXME: When we machine generate the relax table,
+		   machine generate a macro to compute subtype.  */
+		1 /* subtype */,
+		fixups[relax_operand].exp.X_add_symbol,
+		fixups[relax_operand].exp.X_add_number,
+		f);
+      /* Record the operand number with the fragment so md_convert_frag
+	 can use cgen_md_record_fixup to record the appropriate reloc.  */
+      /* FIXME: fr_targ.cgen is used pending deciding whether to
+	 allow a target to add members to fragS.  For more info
+	 see the comment above fr_targ in as.h.  */
+      old_frag->fr_targ.cgen.insn = insn;
+      old_frag->fr_targ.cgen.opindex = fixups[relax_operand].opindex;
+      old_frag->fr_targ.cgen.opinfo = fixups[relax_operand].opinfo;
+    }
+  else
+    f = frag_more (byte_len);
+
+  /* If we're recording insns as numbers (rather than a string of bytes),
+     target byte order handling is deferred until now.  */
+#if 0 /*def CGEN_INT_INSN*/
+  switch (length)
+    {
+    case 16:
+      if (cgen_big_endian_p)
+	bfd_putb16 ((bfd_vma) *buf, f);
+      else
+	bfd_putl16 ((bfd_vma) *buf, f);
+      break;
+    case 32:
+      if (cgen_big_endian_p)
+	bfd_putb32 ((bfd_vma) *buf, f);
+      else
+	bfd_putl32 ((bfd_vma) *buf, f);
+      break;
+    default:
+      abort ();
+    }
+#else
+  memcpy (f, buf, byte_len);
+#endif
+
+  /* Create any fixups.  */
+  for (i = 0; i < num_fixups; ++i)
+    {
+      /* Don't create fixups for these.  That's done during relaxation.
+	 We don't need to test for CGEN_INSN_RELAX as they can't get here
+	 (see above).  */
+      if (CGEN_INSN_ATTR (insn, CGEN_INSN_RELAXABLE) != 0
+	  && CGEN_OPERAND_ATTR (& CGEN_SYM (operand_table) [fixups[i].opindex],
+				CGEN_OPERAND_RELAX) != 0)
+	continue;
+
+#ifndef md_cgen_record_fixup_exp
+#define md_cgen_record_fixup_exp cgen_record_fixup_exp
+#endif
+
+      md_cgen_record_fixup_exp (frag_now, f - frag_now->fr_literal,
+				insn, length,
+				& CGEN_SYM (operand_table) [fixups[i].opindex],
+				fixups[i].opinfo,
+				&fixups[i].exp);
+    }
+}
+
+/* Apply a fixup to the object code.  This is called for all the
+   fixups we generated by the call to fix_new_exp, above.  In the call
+   above we used a reloc code which was the largest legal reloc code
+   plus the operand index.  Here we undo that to recover the operand
+   index.  At this point all symbol values should be fully resolved,
+   and we attempt to completely resolve the reloc.  If we can not do
+   that, we determine the correct reloc code and put it back in the fixup.  */
+
+/* FIXME: This function handles some of the fixups and bfd_install_relocation
+   handles the rest.  bfd_install_relocation (or some other bfd function)
+   should handle them all.  */
+
+int
+cgen_md_apply_fix3 (fixP, valueP, seg)
+     fixS *fixP;
+     valueT *valueP;
+     segT seg;
+{
+  char *where = fixP->fx_frag->fr_literal + fixP->fx_where;
+  valueT value;
+
+  /* FIXME FIXME FIXME: The value we are passed in *valuep includes
+     the symbol values.  Since we are using BFD_ASSEMBLER, if we are
+     doing this relocation the code in write.c is going to call
+     bfd_install_relocation, which is also going to use the symbol
+     value.  That means that if the reloc is fully resolved we want to
+     use *valuep since bfd_install_relocation is not being used.
+     However, if the reloc is not fully resolved we do not want to use
+     *valuep, and must use fx_offset instead.  However, if the reloc
+     is PC relative, we do want to use *valuep since it includes the
+     result of md_pcrel_from.  This is confusing.  */
+
+  if (fixP->fx_addsy == (symbolS *) NULL)
+    {
+      value = *valueP;
+      fixP->fx_done = 1;
+    }
+  else if (fixP->fx_pcrel)
+    value = *valueP;
+  else
+    {
+      value = fixP->fx_offset;
+      if (fixP->fx_subsy != (symbolS *) NULL)
+	{
+	  if (S_GET_SEGMENT (fixP->fx_subsy) == absolute_section)
+	    value -= S_GET_VALUE (fixP->fx_subsy);
+	  else
+	    {
+	      /* We don't actually support subtracting a symbol.  */
+ 	      as_bad_where (fixP->fx_file, fixP->fx_line,
+			    "expression too complex");
+	    }
+	}
+    }
+
+  if ((int) fixP->fx_r_type >= (int) BFD_RELOC_UNUSED)
+    {
+      int opindex = (int) fixP->fx_r_type - (int) BFD_RELOC_UNUSED;
+      const struct cgen_operand *operand = & CGEN_SYM (operand_table) [opindex];
+      const char *errmsg;
+      bfd_reloc_code_real_type reloc_type;
+      struct cgen_fields fields;
+      const struct cgen_insn *insn = (struct cgen_insn *) fixP->tc_fix_data.insn;
+
+      /* If the reloc has been fully resolved finish the operand here.  */
+      /* FIXME: This duplicates the capabilities of code in BFD.  */
+      if (fixP->fx_done
+	  /* FIXME: If partial_inplace isn't set bfd_install_relocation won't
+	     finish the job.  Testing for pcrel is a temporary hack.  */
+	  || fixP->fx_pcrel)
+	{
+	  /* This may seem like overkill, and using bfd_install_relocation or
+	     some such may be preferable, but this is simple.  */
+	  CGEN_FIELDS_BITSIZE (&fields) = CGEN_INSN_BITSIZE (insn);
+	  CGEN_SYM (set_operand) (opindex, &value, &fields);
+	  errmsg = CGEN_SYM (validate_operand) (opindex, &fields);
+	  if (errmsg)
+	    as_warn_where (fixP->fx_file, fixP->fx_line, "%s\n", errmsg);
+	  CGEN_SYM (insert_operand) (opindex, &fields, where);
+	}
+
+      if (fixP->fx_done)
+	return 1;
+
+      /* The operand isn't fully resolved.  Determine a BFD reloc value
+	 based on the operand information and leave it to
+	 bfd_install_relocation.  Note that this doesn't work when
+	 partial_inplace == false.  */
+
+      reloc_type = CGEN_SYM (lookup_reloc) (insn, operand, fixP);
+      if (reloc_type != BFD_RELOC_NONE)
+	{
+	  fixP->fx_r_type = reloc_type;
+	}
+      else
+	{
+	  as_bad_where (fixP->fx_file, fixP->fx_line,
+			"unresolved expression that must be resolved");
+	  fixP->fx_done = 1;
+	  return 1;
+	}
+    }
+  else if (fixP->fx_done)
+    {
+      /* We're finished with this fixup.  Install it because
+	 bfd_install_relocation won't be called to do it.  */
+      switch (fixP->fx_r_type)
+	{
+	case BFD_RELOC_8:
+	  md_number_to_chars (where, value, 1);
+	  break;
+	case BFD_RELOC_16:
+	  md_number_to_chars (where, value, 2);
+	  break;
+	case BFD_RELOC_32:
+	  md_number_to_chars (where, value, 4);
+	  break;
+	/* FIXME: later add support for 64 bits.  */
+	default:
+	  abort ();
+	}
+    }
+  else
+    {
+      /* bfd_install_relocation will be called to finish things up.  */
+    }
+
+  /* Tuck `value' away for use by tc_gen_reloc.
+     See the comment describing fx_addnumber in write.h.
+     This field is misnamed (or misused :-).  */
+  fixP->fx_addnumber = value;
+
+  return 1;
+}
+
+/* Translate internal representation of relocation info to BFD target format.
+
+   FIXME: To what extent can we get all relevant targets to use this?  */
+
+arelent *
+cgen_tc_gen_reloc (section, fixP)
+     asection *section;
+     fixS *fixP;
+{
+  arelent *reloc;
+
+  reloc = (arelent *) bfd_alloc_by_size_t (stdoutput, sizeof (arelent));
+
+  reloc->howto = bfd_reloc_type_lookup (stdoutput, fixP->fx_r_type);
+  if (reloc->howto == (reloc_howto_type *) NULL)
+    {
+      as_bad_where (fixP->fx_file, fixP->fx_line,
+		    "internal error: can't export reloc type %d (`%s')",
+		    fixP->fx_r_type, bfd_get_reloc_code_name (fixP->fx_r_type));
+      return NULL;
+    }
+
+  assert (!fixP->fx_pcrel == !reloc->howto->pc_relative);
+
+  reloc->sym_ptr_ptr = &fixP->fx_addsy->bsym;
+  reloc->address = fixP->fx_frag->fr_address + fixP->fx_where;
+  reloc->addend = fixP->fx_addnumber;
+
+  return reloc;
+}