aboutsummaryrefslogtreecommitdiff
path: root/contrib/binutils/gas/ehopt.c
diff options
context:
space:
mode:
Diffstat (limited to 'contrib/binutils/gas/ehopt.c')
-rw-r--r--contrib/binutils/gas/ehopt.c540
1 files changed, 0 insertions, 540 deletions
diff --git a/contrib/binutils/gas/ehopt.c b/contrib/binutils/gas/ehopt.c
deleted file mode 100644
index 451aaff18c94..000000000000
--- a/contrib/binutils/gas/ehopt.c
+++ /dev/null
@@ -1,540 +0,0 @@
-/* ehopt.c--optimize gcc exception frame information.
- Copyright 1998, 2000, 2001, 2003 Free Software Foundation, Inc.
- Written by Ian Lance Taylor <ian@cygnus.com>.
-
-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 "as.h"
-#include "subsegs.h"
-
-/* We include this ELF file, even though we may not be assembling for
- ELF, since the exception frame information is always in a format
- derived from DWARF. */
-
-#include "elf/dwarf2.h"
-
-/* Try to optimize gcc 2.8 exception frame information.
-
- Exception frame information is emitted for every function in the
- .eh_frame or .debug_frame sections. Simple information for a function
- with no exceptions looks like this:
-
-__FRAME_BEGIN__:
- .4byte .LLCIE1 / Length of Common Information Entry
-.LSCIE1:
-#if .eh_frame
- .4byte 0x0 / CIE Identifier Tag
-#elif .debug_frame
- .4byte 0xffffffff / CIE Identifier Tag
-#endif
- .byte 0x1 / CIE Version
- .byte 0x0 / CIE Augmentation (none)
- .byte 0x1 / ULEB128 0x1 (CIE Code Alignment Factor)
- .byte 0x7c / SLEB128 -4 (CIE Data Alignment Factor)
- .byte 0x8 / CIE RA Column
- .byte 0xc / DW_CFA_def_cfa
- .byte 0x4 / ULEB128 0x4
- .byte 0x4 / ULEB128 0x4
- .byte 0x88 / DW_CFA_offset, column 0x8
- .byte 0x1 / ULEB128 0x1
- .align 4
-.LECIE1:
- .set .LLCIE1,.LECIE1-.LSCIE1 / CIE Length Symbol
- .4byte .LLFDE1 / FDE Length
-.LSFDE1:
- .4byte .LSFDE1-__FRAME_BEGIN__ / FDE CIE offset
- .4byte .LFB1 / FDE initial location
- .4byte .LFE1-.LFB1 / FDE address range
- .byte 0x4 / DW_CFA_advance_loc4
- .4byte .LCFI0-.LFB1
- .byte 0xe / DW_CFA_def_cfa_offset
- .byte 0x8 / ULEB128 0x8
- .byte 0x85 / DW_CFA_offset, column 0x5
- .byte 0x2 / ULEB128 0x2
- .byte 0x4 / DW_CFA_advance_loc4
- .4byte .LCFI1-.LCFI0
- .byte 0xd / DW_CFA_def_cfa_register
- .byte 0x5 / ULEB128 0x5
- .byte 0x4 / DW_CFA_advance_loc4
- .4byte .LCFI2-.LCFI1
- .byte 0x2e / DW_CFA_GNU_args_size
- .byte 0x4 / ULEB128 0x4
- .byte 0x4 / DW_CFA_advance_loc4
- .4byte .LCFI3-.LCFI2
- .byte 0x2e / DW_CFA_GNU_args_size
- .byte 0x0 / ULEB128 0x0
- .align 4
-.LEFDE1:
- .set .LLFDE1,.LEFDE1-.LSFDE1 / FDE Length Symbol
-
- The immediate issue we can address in the assembler is the
- DW_CFA_advance_loc4 followed by a four byte value. The value is
- the difference of two addresses in the function. Since gcc does
- not know this value, it always uses four bytes. We will know the
- value at the end of assembly, so we can do better. */
-
-struct cie_info
-{
- unsigned code_alignment;
- int z_augmentation;
-};
-
-static int get_cie_info (struct cie_info *);
-
-/* Extract information from the CIE. */
-
-static int
-get_cie_info (struct cie_info *info)
-{
- fragS *f;
- fixS *fix;
- int offset;
- char CIE_id;
- char augmentation[10];
- int iaug;
- int code_alignment = 0;
-
- /* We should find the CIE at the start of the section. */
-
-#if defined (BFD_ASSEMBLER) || defined (MANY_SEGMENTS)
- f = seg_info (now_seg)->frchainP->frch_root;
-#else
- f = frchain_now->frch_root;
-#endif
-#ifdef BFD_ASSEMBLER
- fix = seg_info (now_seg)->frchainP->fix_root;
-#else
- fix = *seg_fix_rootP;
-#endif
-
- /* Look through the frags of the section to find the code alignment. */
-
- /* First make sure that the CIE Identifier Tag is 0/-1. */
-
- if (strcmp (segment_name (now_seg), ".debug_frame") == 0)
- CIE_id = (char)0xff;
- else
- CIE_id = 0;
-
- offset = 4;
- while (f != NULL && offset >= f->fr_fix)
- {
- offset -= f->fr_fix;
- f = f->fr_next;
- }
- if (f == NULL
- || f->fr_fix - offset < 4
- || f->fr_literal[offset] != CIE_id
- || f->fr_literal[offset + 1] != CIE_id
- || f->fr_literal[offset + 2] != CIE_id
- || f->fr_literal[offset + 3] != CIE_id)
- return 0;
-
- /* Next make sure the CIE version number is 1. */
-
- offset += 4;
- while (f != NULL && offset >= f->fr_fix)
- {
- offset -= f->fr_fix;
- f = f->fr_next;
- }
- if (f == NULL
- || f->fr_fix - offset < 1
- || f->fr_literal[offset] != 1)
- return 0;
-
- /* Skip the augmentation (a null terminated string). */
-
- iaug = 0;
- ++offset;
- while (1)
- {
- while (f != NULL && offset >= f->fr_fix)
- {
- offset -= f->fr_fix;
- f = f->fr_next;
- }
- if (f == NULL)
- return 0;
-
- while (offset < f->fr_fix && f->fr_literal[offset] != '\0')
- {
- if ((size_t) iaug < (sizeof augmentation) - 1)
- {
- augmentation[iaug] = f->fr_literal[offset];
- ++iaug;
- }
- ++offset;
- }
- if (offset < f->fr_fix)
- break;
- }
- ++offset;
- while (f != NULL && offset >= f->fr_fix)
- {
- offset -= f->fr_fix;
- f = f->fr_next;
- }
- if (f == NULL)
- return 0;
-
- augmentation[iaug] = '\0';
- if (augmentation[0] == '\0')
- {
- /* No augmentation. */
- }
- else if (strcmp (augmentation, "eh") == 0)
- {
- /* We have to skip a pointer. Unfortunately, we don't know how
- large it is. We find out by looking for a matching fixup. */
- while (fix != NULL
- && (fix->fx_frag != f || fix->fx_where != offset))
- fix = fix->fx_next;
- if (fix == NULL)
- offset += 4;
- else
- offset += fix->fx_size;
- while (f != NULL && offset >= f->fr_fix)
- {
- offset -= f->fr_fix;
- f = f->fr_next;
- }
- if (f == NULL)
- return 0;
- }
- else if (augmentation[0] != 'z')
- return 0;
-
- /* We're now at the code alignment factor, which is a ULEB128. If
- it isn't a single byte, forget it. */
-
- code_alignment = f->fr_literal[offset] & 0xff;
- if ((code_alignment & 0x80) != 0)
- code_alignment = 0;
-
- info->code_alignment = code_alignment;
- info->z_augmentation = (augmentation[0] == 'z');
-
- return 1;
-}
-
-/* This function is called from emit_expr. It looks for cases which
- we can optimize.
-
- Rather than try to parse all this information as we read it, we
- look for a single byte DW_CFA_advance_loc4 followed by a 4 byte
- difference. We turn that into a rs_cfa_advance frag, and handle
- those frags at the end of the assembly. If the gcc output changes
- somewhat, this optimization may stop working.
-
- This function returns non-zero if it handled the expression and
- emit_expr should not do anything, or zero otherwise. It can also
- change *EXP and *PNBYTES. */
-
-int
-check_eh_frame (expressionS *exp, unsigned int *pnbytes)
-{
- struct frame_data
- {
- enum frame_state
- {
- state_idle,
- state_saw_size,
- state_saw_cie_offset,
- state_saw_pc_begin,
- state_seeing_aug_size,
- state_skipping_aug,
- state_wait_loc4,
- state_saw_loc4,
- state_error,
- } state;
-
- int cie_info_ok;
- struct cie_info cie_info;
-
- symbolS *size_end_sym;
- fragS *loc4_frag;
- int loc4_fix;
-
- int aug_size;
- int aug_shift;
- };
-
- static struct frame_data eh_frame_data;
- static struct frame_data debug_frame_data;
- struct frame_data *d;
-
- /* Don't optimize. */
- if (flag_traditional_format)
- return 0;
-
- /* Select the proper section data. */
- if (strcmp (segment_name (now_seg), ".eh_frame") == 0)
- d = &eh_frame_data;
- else if (strcmp (segment_name (now_seg), ".debug_frame") == 0)
- d = &debug_frame_data;
- else
- return 0;
-
- if (d->state >= state_saw_size && S_IS_DEFINED (d->size_end_sym))
- {
- /* We have come to the end of the CIE or FDE. See below where
- we set saw_size. We must check this first because we may now
- be looking at the next size. */
- d->state = state_idle;
- }
-
- switch (d->state)
- {
- case state_idle:
- if (*pnbytes == 4)
- {
- /* This might be the size of the CIE or FDE. We want to know
- the size so that we don't accidentally optimize across an FDE
- boundary. We recognize the size in one of two forms: a
- symbol which will later be defined as a difference, or a
- subtraction of two symbols. Either way, we can tell when we
- are at the end of the FDE because the symbol becomes defined
- (in the case of a subtraction, the end symbol, from which the
- start symbol is being subtracted). Other ways of describing
- the size will not be optimized. */
- if ((exp->X_op == O_symbol || exp->X_op == O_subtract)
- && ! S_IS_DEFINED (exp->X_add_symbol))
- {
- d->state = state_saw_size;
- d->size_end_sym = exp->X_add_symbol;
- }
- }
- break;
-
- case state_saw_size:
- case state_saw_cie_offset:
- /* Assume whatever form it appears in, it appears atomically. */
- d->state += 1;
- break;
-
- case state_saw_pc_begin:
- /* Decide whether we should see an augmentation. */
- if (! d->cie_info_ok
- && ! (d->cie_info_ok = get_cie_info (&d->cie_info)))
- d->state = state_error;
- else if (d->cie_info.z_augmentation)
- {
- d->state = state_seeing_aug_size;
- d->aug_size = 0;
- d->aug_shift = 0;
- }
- else
- d->state = state_wait_loc4;
- break;
-
- case state_seeing_aug_size:
- /* Bytes == -1 means this comes from an leb128 directive. */
- if ((int)*pnbytes == -1 && exp->X_op == O_constant)
- {
- d->aug_size = exp->X_add_number;
- d->state = state_skipping_aug;
- }
- else if (*pnbytes == 1 && exp->X_op == O_constant)
- {
- unsigned char byte = exp->X_add_number;
- d->aug_size |= (byte & 0x7f) << d->aug_shift;
- d->aug_shift += 7;
- if ((byte & 0x80) == 0)
- d->state = state_skipping_aug;
- }
- else
- d->state = state_error;
- if (d->state == state_skipping_aug && d->aug_size == 0)
- d->state = state_wait_loc4;
- break;
-
- case state_skipping_aug:
- if ((int)*pnbytes < 0)
- d->state = state_error;
- else
- {
- int left = (d->aug_size -= *pnbytes);
- if (left == 0)
- d->state = state_wait_loc4;
- else if (left < 0)
- d->state = state_error;
- }
- break;
-
- case state_wait_loc4:
- if (*pnbytes == 1
- && exp->X_op == O_constant
- && exp->X_add_number == DW_CFA_advance_loc4)
- {
- /* This might be a DW_CFA_advance_loc4. Record the frag and the
- position within the frag, so that we can change it later. */
- frag_grow (1);
- d->state = state_saw_loc4;
- d->loc4_frag = frag_now;
- d->loc4_fix = frag_now_fix ();
- }
- break;
-
- case state_saw_loc4:
- d->state = state_wait_loc4;
- if (*pnbytes != 4)
- break;
- if (exp->X_op == O_constant)
- {
- /* This is a case which we can optimize. The two symbols being
- subtracted were in the same frag and the expression was
- reduced to a constant. We can do the optimization entirely
- in this function. */
- if (d->cie_info.code_alignment > 0
- && exp->X_add_number % d->cie_info.code_alignment == 0
- && exp->X_add_number / d->cie_info.code_alignment < 0x40)
- {
- d->loc4_frag->fr_literal[d->loc4_fix]
- = DW_CFA_advance_loc
- | (exp->X_add_number / d->cie_info.code_alignment);
- /* No more bytes needed. */
- return 1;
- }
- else if (exp->X_add_number < 0x100)
- {
- d->loc4_frag->fr_literal[d->loc4_fix] = DW_CFA_advance_loc1;
- *pnbytes = 1;
- }
- else if (exp->X_add_number < 0x10000)
- {
- d->loc4_frag->fr_literal[d->loc4_fix] = DW_CFA_advance_loc2;
- *pnbytes = 2;
- }
- }
- else if (exp->X_op == O_subtract)
- {
- /* This is a case we can optimize. The expression was not
- reduced, so we can not finish the optimization until the end
- of the assembly. We set up a variant frag which we handle
- later. */
- int fr_subtype;
-
- if (d->cie_info.code_alignment > 0)
- fr_subtype = d->cie_info.code_alignment << 3;
- else
- fr_subtype = 0;
-
- frag_var (rs_cfa, 4, 0, fr_subtype, make_expr_symbol (exp),
- d->loc4_fix, (char *) d->loc4_frag);
- return 1;
- }
- break;
-
- case state_error:
- /* Just skipping everything. */
- break;
- }
-
- return 0;
-}
-
-/* The function estimates the size of a rs_cfa variant frag based on
- the current values of the symbols. It is called before the
- relaxation loop. We set fr_subtype{0:2} to the expected length. */
-
-int
-eh_frame_estimate_size_before_relax (fragS *frag)
-{
- offsetT diff;
- int ca = frag->fr_subtype >> 3;
- int ret;
-
- diff = resolve_symbol_value (frag->fr_symbol);
-
- if (ca > 0 && diff % ca == 0 && diff / ca < 0x40)
- ret = 0;
- else if (diff < 0x100)
- ret = 1;
- else if (diff < 0x10000)
- ret = 2;
- else
- ret = 4;
-
- frag->fr_subtype = (frag->fr_subtype & ~7) | ret;
-
- return ret;
-}
-
-/* This function relaxes a rs_cfa variant frag based on the current
- values of the symbols. fr_subtype{0:2} is the current length of
- the frag. This returns the change in frag length. */
-
-int
-eh_frame_relax_frag (fragS *frag)
-{
- int oldsize, newsize;
-
- oldsize = frag->fr_subtype & 7;
- newsize = eh_frame_estimate_size_before_relax (frag);
- return newsize - oldsize;
-}
-
-/* This function converts a rs_cfa variant frag into a normal fill
- frag. This is called after all relaxation has been done.
- fr_subtype{0:2} will be the desired length of the frag. */
-
-void
-eh_frame_convert_frag (fragS *frag)
-{
- offsetT diff;
- fragS *loc4_frag;
- int loc4_fix;
-
- loc4_frag = (fragS *) frag->fr_opcode;
- loc4_fix = (int) frag->fr_offset;
-
- diff = resolve_symbol_value (frag->fr_symbol);
-
- switch (frag->fr_subtype & 7)
- {
- case 0:
- {
- int ca = frag->fr_subtype >> 3;
- assert (ca > 0 && diff % ca == 0 && diff / ca < 0x40);
- loc4_frag->fr_literal[loc4_fix] = DW_CFA_advance_loc | (diff / ca);
- }
- break;
-
- case 1:
- assert (diff < 0x100);
- loc4_frag->fr_literal[loc4_fix] = DW_CFA_advance_loc1;
- frag->fr_literal[frag->fr_fix] = diff;
- break;
-
- case 2:
- assert (diff < 0x10000);
- loc4_frag->fr_literal[loc4_fix] = DW_CFA_advance_loc2;
- md_number_to_chars (frag->fr_literal + frag->fr_fix, diff, 2);
- break;
-
- default:
- md_number_to_chars (frag->fr_literal + frag->fr_fix, diff, 4);
- break;
- }
-
- frag->fr_fix += frag->fr_subtype & 7;
- frag->fr_type = rs_fill;
- frag->fr_subtype = 0;
- frag->fr_offset = 0;
-}
generated by cgit v1.2.3 (git 2.25.1) at 2025-02-22 08:57:10 +0000