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* 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.
This commit is contained in:
Richard Henderson 2001-05-14 22:37:47 +00:00
parent 1ff55c930c
commit 67a659f60e
3 changed files with 222 additions and 149 deletions
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11
gas/ChangeLog
View File

@ -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

353
gas/ehopt.c
View File

@ -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;
};
/* Get the code alignment factor from the CIE. */
static int get_cie_info PARAMS ((struct cie_info *));
/* 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;
break;
/* 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. */
case state_saw_size:
case state_saw_cie_offset:
/* Assume whatever form it appears in, it appears atomically. */
d->state += 1;
break;
d->saw_advance_loc4 = 0;
ca = eh_frame_code_alignment (1);
if (ca < 0)
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. */
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;
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;
}
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;
}
break;
case state_error:
/* Just skipping everything. */
break;
}
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. */
d->saw_advance_loc4 = 0;
frag_var (rs_cfa, 4, 0, 0, make_expr_symbol (exp),
d->loc4_fix, (char *) d->loc4_frag);
return 1;
}
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)
switch (frag->fr_subtype & 7)
{
int ca;
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;
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)
{
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;

7
gas/read.c
View File

@ -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. */