From 841eff9e79feef61fa9ada5ec008514385750642 Mon Sep 17 00:00:00 2001 From: David Edelsohn Date: Thu, 10 Apr 1997 21:51:01 +0000 Subject: [PATCH] Tweak comment. --- gas/cgen.c | 511 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 511 insertions(+) create mode 100644 gas/cgen.c diff --git a/gas/cgen.c b/gas/cgen.c new file mode 100644 index 00000000000..355268faa9d --- /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; +} -- 2.30.2