/* frags.c - manage frags - Copyright 1987, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2003, 2004 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, 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA. */ #include "as.h" #include "subsegs.h" #include "obstack.h" extern fragS zero_address_frag; extern fragS bss_address_frag; /* Initialization for frag routines. */ void frag_init (void) { zero_address_frag.fr_type = rs_fill; bss_address_frag.fr_type = rs_fill; } /* Check that we're not trying to assemble into a section that can't allocate frags (currently, this is only possible in the absolute section), or into an mri common. */ static void frag_alloc_check (const struct obstack *ob) { if (ob->chunk_size == 0) { as_bad (_("attempt to allocate data in absolute section")); subseg_set (text_section, 0); } if (mri_common_symbol != NULL) { as_bad (_("attempt to allocate data in common section")); mri_common_symbol = NULL; } } /* Allocate a frag on the specified obstack. Call this routine from everywhere else, so that all the weird alignment hackery can be done in just one place. */ fragS * frag_alloc (struct obstack *ob) { fragS *ptr; int oalign; (void) obstack_alloc (ob, 0); oalign = obstack_alignment_mask (ob); obstack_alignment_mask (ob) = 0; ptr = (fragS *) obstack_alloc (ob, SIZEOF_STRUCT_FRAG); obstack_alignment_mask (ob) = oalign; memset (ptr, 0, SIZEOF_STRUCT_FRAG); return ptr; } /* Try to augment current frag by nchars chars. If there is no room, close of the current frag with a ".fill 0" and begin a new frag. Unless the new frag has nchars chars available do not return. Do not set up any fields of *now_frag. */ void frag_grow (unsigned int nchars) { if (obstack_room (&frchain_now->frch_obstack) < nchars) { unsigned int n; long oldc; frag_wane (frag_now); frag_new (0); oldc = frchain_now->frch_obstack.chunk_size; frchain_now->frch_obstack.chunk_size = 2 * nchars + SIZEOF_STRUCT_FRAG; if (frchain_now->frch_obstack.chunk_size > 0) while ((n = obstack_room (&frchain_now->frch_obstack)) < nchars && (unsigned long) frchain_now->frch_obstack.chunk_size > nchars) { frag_wane (frag_now); frag_new (0); } frchain_now->frch_obstack.chunk_size = oldc; } if (obstack_room (&frchain_now->frch_obstack) < nchars) as_fatal (_("can't extend frag %u chars"), nchars); } /* Call this to close off a completed frag, and start up a new (empty) frag, in the same subsegment as the old frag. [frchain_now remains the same but frag_now is updated.] Because this calculates the correct value of fr_fix by looking at the obstack 'frags', it needs to know how many characters at the end of the old frag belong to the maximal variable part; The rest must belong to fr_fix. It doesn't actually set up the old frag's fr_var. You may have set fr_var == 1, but allocated 10 chars to the end of the frag; In this case you pass old_frags_var_max_size == 10. In fact, you may use fr_var for something totally unrelated to the size of the variable part of the frag; None of the generic frag handling code makes use of fr_var. Make a new frag, initialising some components. Link new frag at end of frchain_now. */ void frag_new (int old_frags_var_max_size /* Number of chars (already allocated on obstack frags) in variable_length part of frag. */) { fragS *former_last_fragP; frchainS *frchP; assert (frchain_now->frch_last == frag_now); /* Fix up old frag's fr_fix. */ frag_now->fr_fix = frag_now_fix_octets () - old_frags_var_max_size; /* Make sure its type is valid. */ assert (frag_now->fr_type != 0); /* This will align the obstack so the next struct we allocate on it will begin at a correct boundary. */ obstack_finish (&frchain_now->frch_obstack); frchP = frchain_now; know (frchP); former_last_fragP = frchP->frch_last; assert (former_last_fragP != 0); assert (former_last_fragP == frag_now); frag_now = frag_alloc (&frchP->frch_obstack); as_where (&frag_now->fr_file, &frag_now->fr_line); /* Generally, frag_now->points to an address rounded up to next alignment. However, characters will add to obstack frags IMMEDIATELY after the struct frag, even if they are not starting at an alignment address. */ former_last_fragP->fr_next = frag_now; frchP->frch_last = frag_now; #ifndef NO_LISTING { extern struct list_info_struct *listing_tail; frag_now->line = listing_tail; } #endif assert (frchain_now->frch_last == frag_now); frag_now->fr_next = NULL; } /* Start a new frag unless we have n more chars of room in the current frag. Close off the old frag with a .fill 0. Return the address of the 1st char to write into. Advance frag_now_growth past the new chars. */ char * frag_more (int nchars) { register char *retval; frag_alloc_check (&frchain_now->frch_obstack); frag_grow (nchars); retval = obstack_next_free (&frchain_now->frch_obstack); obstack_blank_fast (&frchain_now->frch_obstack, nchars); return (retval); } /* Start a new frag unless we have max_chars more chars of room in the current frag. Close off the old frag with a .fill 0. Set up a machine_dependent relaxable frag, then start a new frag. Return the address of the 1st char of the var part of the old frag to write into. */ char * frag_var (relax_stateT type, int max_chars, int var, relax_substateT subtype, symbolS *symbol, offsetT offset, char *opcode) { register char *retval; frag_grow (max_chars); retval = obstack_next_free (&frchain_now->frch_obstack); obstack_blank_fast (&frchain_now->frch_obstack, max_chars); frag_now->fr_var = var; frag_now->fr_type = type; frag_now->fr_subtype = subtype; frag_now->fr_symbol = symbol; frag_now->fr_offset = offset; frag_now->fr_opcode = opcode; #ifdef USING_CGEN frag_now->fr_cgen.insn = 0; frag_now->fr_cgen.opindex = 0; frag_now->fr_cgen.opinfo = 0; #endif #ifdef TC_FRAG_INIT TC_FRAG_INIT (frag_now); #endif as_where (&frag_now->fr_file, &frag_now->fr_line); frag_new (max_chars); return (retval); } /* OVE: This variant of frag_var assumes that space for the tail has been allocated by caller. No call to frag_grow is done. */ char * frag_variant (relax_stateT type, int max_chars, int var, relax_substateT subtype, symbolS *symbol, offsetT offset, char *opcode) { register char *retval; retval = obstack_next_free (&frchain_now->frch_obstack); frag_now->fr_var = var; frag_now->fr_type = type; frag_now->fr_subtype = subtype; frag_now->fr_symbol = symbol; frag_now->fr_offset = offset; frag_now->fr_opcode = opcode; #ifdef USING_CGEN frag_now->fr_cgen.insn = 0; frag_now->fr_cgen.opindex = 0; frag_now->fr_cgen.opinfo = 0; #endif #ifdef TC_FRAG_INIT TC_FRAG_INIT (frag_now); #endif as_where (&frag_now->fr_file, &frag_now->fr_line); frag_new (max_chars); return (retval); } /* Reduce the variable end of a frag to a harmless state. */ void frag_wane (register fragS *fragP) { fragP->fr_type = rs_fill; fragP->fr_offset = 0; fragP->fr_var = 0; } /* Return the number of bytes by which the current frag can be grown. */ int frag_room (void) { return obstack_room (&frchain_now->frch_obstack); } /* Make an alignment frag. The size of this frag will be adjusted to force the next frag to have the appropriate alignment. ALIGNMENT is the power of two to which to align. FILL_CHARACTER is the character to use to fill in any bytes which are skipped. MAX is the maximum number of characters to skip when doing the alignment, or 0 if there is no maximum. */ void frag_align (int alignment, int fill_character, int max) { if (now_seg == absolute_section) { addressT new_off; addressT mask; mask = (~(addressT) 0) << alignment; new_off = (abs_section_offset + ~mask) & mask; if (max == 0 || new_off - abs_section_offset <= (addressT) max) abs_section_offset = new_off; } else { char *p; p = frag_var (rs_align, 1, 1, (relax_substateT) max, (symbolS *) 0, (offsetT) alignment, (char *) 0); *p = fill_character; } } /* Make an alignment frag like frag_align, but fill with a repeating pattern rather than a single byte. ALIGNMENT is the power of two to which to align. FILL_PATTERN is the fill pattern to repeat in the bytes which are skipped. N_FILL is the number of bytes in FILL_PATTERN. MAX is the maximum number of characters to skip when doing the alignment, or 0 if there is no maximum. */ void frag_align_pattern (int alignment, const char *fill_pattern, int n_fill, int max) { char *p; p = frag_var (rs_align, n_fill, n_fill, (relax_substateT) max, (symbolS *) 0, (offsetT) alignment, (char *) 0); memcpy (p, fill_pattern, n_fill); } /* The NOP_OPCODE is for the alignment fill value. Fill it with a nop instruction so that the disassembler does not choke on it. */ #ifndef NOP_OPCODE #define NOP_OPCODE 0x00 #endif /* Use this to restrict the amount of memory allocated for representing the alignment code. Needs to be large enough to hold any fixed sized prologue plus the replicating portion. */ #ifndef MAX_MEM_FOR_RS_ALIGN_CODE /* Assume that if HANDLE_ALIGN is not defined then no special action is required to code fill, which means that we get just repeat the one NOP_OPCODE byte. */ # ifndef HANDLE_ALIGN # define MAX_MEM_FOR_RS_ALIGN_CODE 1 # else # define MAX_MEM_FOR_RS_ALIGN_CODE ((1 << alignment) - 1) # endif #endif void frag_align_code (int alignment, int max) { char *p; p = frag_var (rs_align_code, MAX_MEM_FOR_RS_ALIGN_CODE, 1, (relax_substateT) max, (symbolS *) 0, (offsetT) alignment, (char *) 0); *p = NOP_OPCODE; } addressT frag_now_fix_octets (void) { if (now_seg == absolute_section) return abs_section_offset; return ((char *) obstack_next_free (&frchain_now->frch_obstack) - frag_now->fr_literal); } addressT frag_now_fix (void) { return frag_now_fix_octets () / OCTETS_PER_BYTE; } void frag_append_1_char (int datum) { frag_alloc_check (&frchain_now->frch_obstack); if (obstack_room (&frchain_now->frch_obstack) <= 1) { frag_wane (frag_now); frag_new (0); } obstack_1grow (&frchain_now->frch_obstack, datum); }