diff options
| -rw-r--r-- | gas/ChangeLog | 11 | ||||
| -rw-r--r-- | gas/ehopt.c | 347 | ||||
| -rw-r--r-- | gas/read.c | 7 |
3 files changed, 219 insertions, 146 deletions
diff --git a/gas/ChangeLog b/gas/ChangeLog index 3c725a39ab..cc46dcd016 100644 --- a/gas/ChangeLog +++ b/gas/ChangeLog @@ -1,3 +1,14 @@ +2001-05-14 Richard Henderson <rth@redhat.com> + + * ehopt.c (get_cie_info): Rename from eh_frame_code_alignment; + also collect whether to expect an FDE augmentation. + (check_eh_frame): Rewrite as a state machine. Track where in + an FDE we are located, skip any augmentation. + (eh_frame_estimate_size_before_relax): Get code alignment from + the fragment subtype. + (eh_frame_relax_frag, eh_frame_convert_frag): Likewise. + * read.c (emit_leb128_expr): Call check_eh_frame. + 2001-05-14 Alexandre Oliva <aoliva@redhat.com> * config/tc-mn10300.c (md_assemble): Anchor dwarf2 line info diff --git a/gas/ehopt.c b/gas/ehopt.c index 75ad67ce93..e556e29d17 100644 --- a/gas/ehopt.c +++ b/gas/ehopt.c @@ -88,30 +88,27 @@ __FRAME_BEGIN__: not know this value, it always uses four bytes. We will know the value at the end of assembly, so we can do better. */ -static int eh_frame_code_alignment PARAMS ((int)); +struct cie_info +{ + unsigned code_alignment; + int z_augmentation; +}; + +static int get_cie_info PARAMS ((struct cie_info *)); -/* Get the code alignment factor from the CIE. */ +/* Extract information from the CIE. */ static int -eh_frame_code_alignment (in_seg) - int in_seg; +get_cie_info (info) + struct cie_info *info; { - /* ??? Assume .eh_frame and .debug_frame have the same alignment. */ - static int code_alignment; - fragS *f; fixS *fix; int offset; char CIE_id; char augmentation[10]; int iaug; - - if (code_alignment != 0) - return code_alignment; - - /* Can't find the alignment if we've changed sections. */ - if (! in_seg) - return -1; + int code_alignment = 0; /* We should find the CIE at the start of the section. */ @@ -147,10 +144,7 @@ eh_frame_code_alignment (in_seg) || f->fr_literal[offset + 1] != CIE_id || f->fr_literal[offset + 2] != CIE_id || f->fr_literal[offset + 3] != CIE_id) - { - code_alignment = -1; - return -1; - } + return 0; /* Next make sure the CIE version number is 1. */ @@ -163,10 +157,7 @@ eh_frame_code_alignment (in_seg) if (f == NULL || f->fr_fix - offset < 1 || f->fr_literal[offset] != 1) - { - code_alignment = -1; - return -1; - } + return 0; /* Skip the augmentation (a null terminated string). */ @@ -180,10 +171,8 @@ eh_frame_code_alignment (in_seg) f = f->fr_next; } if (f == NULL) - { - code_alignment = -1; - return -1; - } + return 0; + while (offset < f->fr_fix && f->fr_literal[offset] != '\0') { if ((size_t) iaug < (sizeof augmentation) - 1) @@ -203,10 +192,7 @@ eh_frame_code_alignment (in_seg) f = f->fr_next; } if (f == NULL) - { - code_alignment = -1; - return -1; - } + return 0; augmentation[iaug] = '\0'; if (augmentation[0] == '\0') @@ -230,28 +216,22 @@ eh_frame_code_alignment (in_seg) f = f->fr_next; } if (f == NULL) - { - code_alignment = -1; - return -1; - } - } - else - { - code_alignment = -1; - return -1; + 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) - { - code_alignment = -1; - return -1; - } + if ((code_alignment & 0x80) != 0) + code_alignment = 0; - return code_alignment; + 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 @@ -274,11 +254,28 @@ check_eh_frame (exp, 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 saw_size; - int saw_advance_loc4; int loc4_fix; + + int aug_size; + int aug_shift; }; static struct frame_data eh_frame_data; @@ -297,123 +294,177 @@ check_eh_frame (exp, pnbytes) else return 0; - if (d->saw_size && S_IS_DEFINED (d->size_end_sym)) + 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->saw_size = 0; - d->saw_advance_loc4 = 0; + d->state = state_idle; } - if (! d->saw_size - && *pnbytes == 4) + switch (d->state) { - /* 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)) + case state_idle: + if (*pnbytes == 4) { - d->saw_size = 1; - d->size_end_sym = exp->X_add_symbol; + /* 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; + } } - } - else if (d->saw_size - && *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. */ - d->saw_advance_loc4 = 1; - frag_grow (1); - d->loc4_frag = frag_now; - d->loc4_fix = frag_now_fix (); - } - else if (d->saw_advance_loc4 - && *pnbytes == 4 - && exp->X_op == O_constant) - { - int ca; - - /* 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. */ - - d->saw_advance_loc4 = 0; - - ca = eh_frame_code_alignment (1); - if (ca < 0) + 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) { - /* Don't optimize. */ + d->state = state_seeing_aug_size; + d->aug_size = 0; + d->aug_shift = 0; } - else if (exp->X_add_number % ca == 0 - && exp->X_add_number / ca < 0x40) + 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->loc4_frag->fr_literal[d->loc4_fix] - = DW_CFA_advance_loc | (exp->X_add_number / ca); - /* No more bytes needed. */ - return 1; + d->aug_size = exp->X_add_number; + d->state = state_skipping_aug; } - else if (exp->X_add_number < 0x100) + else if (*pnbytes == 1 && exp->X_op == O_constant) { - d->loc4_frag->fr_literal[d->loc4_fix] = DW_CFA_advance_loc1; - *pnbytes = 1; + 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 if (exp->X_add_number < 0x10000) + else + d->state = state_error; + break; + + case state_skipping_aug: + if ((int)*pnbytes < 0) + d->state = state_error; + else { - d->loc4_frag->fr_literal[d->loc4_fix] = DW_CFA_advance_loc2; - *pnbytes = 2; + int left = (d->aug_size -= *pnbytes); + if (left == 0) + d->state = state_wait_loc4; + else if (left < 0) + d->state = state_error; } - } - else if (d->saw_advance_loc4 - && *pnbytes == 4 - && 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. */ + break; - d->saw_advance_loc4 = 0; + 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; - frag_var (rs_cfa, 4, 0, 0, make_expr_symbol (exp), - d->loc4_fix, (char *) d->loc4_frag); + 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; - return 1; + case state_error: + /* Just skipping everything. */ + break; } - else - d->saw_advance_loc4 = 0; 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 to the expected length. */ + relaxation loop. We set fr_subtype{0:2} to the expected length. */ int eh_frame_estimate_size_before_relax (frag) fragS *frag; { - int ca; offsetT diff; + int ca = frag->fr_subtype >> 3; int ret; - ca = eh_frame_code_alignment (0); diff = resolve_symbol_value (frag->fr_symbol, 0); - if (ca < 0) - ret = 4; - else if (diff % ca == 0 && diff / ca < 0x40) + if (ca > 0 && diff % ca == 0 && diff / ca < 0x40) ret = 0; else if (diff < 0x100) ret = 1; @@ -422,14 +473,14 @@ eh_frame_estimate_size_before_relax (frag) else ret = 4; - frag->fr_subtype = ret; + 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 is the current length of the - frag. This returns the change in frag length. */ + 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 (frag) @@ -437,14 +488,14 @@ eh_frame_relax_frag (frag) { int oldsize, newsize; - oldsize = frag->fr_subtype; + 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 will be the desired length of the frag. */ + fr_subtype{0:2} will be the desired length of the frag. */ void eh_frame_convert_frag (frag) @@ -459,28 +510,32 @@ eh_frame_convert_frag (frag) diff = resolve_symbol_value (frag->fr_symbol, finalize_syms); - if (frag->fr_subtype == 0) - { - int ca; - - ca = eh_frame_code_alignment (0); - assert (ca > 0 && diff % ca == 0 && diff / ca < 0x40); - loc4_frag->fr_literal[loc4_fix] = DW_CFA_advance_loc | (diff / ca); - } - else if (frag->fr_subtype == 1) + 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; - } - else if (frag->fr_subtype == 2) - { + 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; } - else - md_number_to_chars (frag->fr_literal + frag->fr_fix, diff, 4); frag->fr_fix += frag->fr_subtype; frag->fr_type = rs_fill; diff --git a/gas/read.c b/gas/read.c index beb761f371..209ab6ad08 100644 --- a/gas/read.c +++ b/gas/read.c @@ -4393,6 +4393,7 @@ emit_leb128_expr (exp, sign) int sign; { operatorT op = exp->X_op; + int nbytes; if (op == O_absent || op == O_illegal) { @@ -4412,6 +4413,12 @@ emit_leb128_expr (exp, sign) op = O_constant; } + /* Let check_eh_frame know that data is being emitted. nbytes == -1 is + a signal that this is leb128 data. It shouldn't optimize this away. */ + nbytes = -1; + if (check_eh_frame (exp, &nbytes)) + abort (); + if (op == O_constant) { /* If we've got a constant, emit the thing directly right now. */ |
