GCC后端及汇编发布（29）

9.5.9.

其它

从
create_automata

返回，然后是
generate

，接着看
expand_automata

。

expand_automata (continued)

9847

if (!have_error

)

9848

{

9849

generate
();

9850

check_automata_insn_issues
();

9851

}

9852

if (!have_error

)

9853

{

9854

form_important_insn_automata_lists
();

9855

if (progress_flag

)

9856

fprintf (stderr

, "Generation of
attributes...");

9857

make_internal_dfa_insn_code_attr
();

9858

make_insn_alts_attr
();

9859

make_default_insn_latency_attr
();

9860

make_bypass_attr
();

9861

if (progress_flag

)

9862

fprintf (stderr, "done/n");

9863

}

9864

ticker_off (&generation_time

);

9865

ticker_off (&all_time

);

9866

if (progress_flag

)

9867

fprintf (stderr

, "All other genattrtab
stuff...");

9868

}

在
expand_automata

的
9850
行，
check_automata_insn_issues

检查是否存在不会被发布的指令类别，这意味着这个
define_insn_reservation
是错误的。

9687

static
void

9688

check_automata_insn_issues

(void)

in genautomata.c

9689

{

9690

automaton_t
automaton;

9691

ainsn_t ainsn, reserv_ainsn;

9692

9693

for
(automaton = description

->first_automaton;

9694

automaton != NULL;

9695

automaton = automaton->next_automaton)

9696

{

9697

for
(ainsn = automaton->ainsn_list;

9698

ainsn != NULL;

9699

ainsn = ainsn->next_ainsn)

9700

if
(ainsn->first_insn_with_same_reservs && !ainsn->arc_exists_p)

9701

{

9702

for
(reserv_ainsn = ainsn;

9703

reserv_ainsn != NULL;

9704

reserv_ainsn = reserv_ainsn->next_same_reservs_insn)

9705

if
(automaton->corresponding_automaton_decl != NULL)

9706

{

9707

if (!w_flag

)

9708

error ("Automaton `%s': Insn
`%s' will never be issued",

9709

automaton->corresponding_automaton_decl->name,

9710

reserv_ainsn->insn_reserv_decl->name);

9711

else

9712

warning

9713

("Automaton `%s': Insn
`%s' will never be issued",

9714

automaton->corresponding_automaton_decl->name,

9715

reserv_ainsn->insn_reserv_decl->name);

9716

}

9717

else

9718

{

9719

if (!w_flag

)

9720

error ("Insn `%s' will never
be issued",

9721

reserv_ainsn->insn_reserv_decl->name);

9722

else

9723

warning ("Insn `%s' will
never be issued",

9724

reserv_ainsn->insn_reserv_decl->name);

9725

}

9726

}

9727

}

9728

}

接着在
expand_automata

的
9854
行，
form_important_insn_automata_lists

过滤掉不包含有效状态迁移的自动机。

9744

static
void

9745

form_important_insn_automata_lists

(void)

in genautomata.c

9746

{

9747

automaton_t
automaton;

9748

state_t
*state_ptr;

9749

decl_t decl;

9750

ainsn_t ainsn;

9751

arc_t arc;

9752

int i;

9753

9754

VLA_PTR_CREATE (automaton_states

, 1500,

9755

"automaton states for
forming important insn automata sets");

9756

/* Mark important
ainsns.
*/

9757

for
(automaton = description

->first_automaton;

9758

automaton != NULL;

9759

automaton = automaton->next_automaton)

9760

{

9761

VLA_PTR_NULLIFY (automaton_states

);

9762

pass_states

(automaton,
add_automaton_state

);

9763

for
(state_ptr = VLA_PTR_BEGIN (automaton_states

);

9764

state_ptr <= (
state_t

*)
VLA_PTR_LAST (automaton_states

);

9765

state_ptr++)

9766

{

9767

for
(arc
= first_out_arc (*state_ptr);

9768

arc != NULL;

9769

arc = next_out_arc (arc))

9770

if (arc->to_state != *state_ptr)

9771

{

9772

if
(!arc->insn->first_insn_with_same_reservs)

9773

abort ();

9774

for
(ainsn = arc->insn;

9775

ainsn != NULL;

9776

ainsn =
ainsn->next_same_reservs_insn)

9777

ainsn->important_p = TRUE;

9778

}

9779

}

9780

}

9781

VLA_PTR_DELETE (automaton_states

);

9782

/* Create automata
sets for the insns.

*/

9783

for
(i = 0; i < description

->decls_num; i++)

9784

{

9785

decl = description

->decls [i];

9786

if (decl->mode == dm_insn_reserv)

9787

{

9788

automata_list_start ();

9789

for
(automaton = description->first_automaton;

9790

automaton != NULL;

9791

automaton =
automaton->next_automaton)

9792

for
(ainsn
= automaton->ainsn_list;

9793

ainsn != NULL;

9794

ainsn = ainsn->next_ainsn)

9795

if (ainsn->important_p

9796

&& ainsn->insn_reserv_decl ==
DECL_INSN_RESERV (decl))

9797

{

9798

automata_list_add (automaton);

9799

break
;

9800

}

9801

DECL_INSN_RESERV (decl)->important_automata_list

9802

= automata_list_finish ();

9803

}

9804

}

9805

}

上面在
9762
行
，
pass_states

从自动机的
start_state

开始通过状态迁移遍历所有的状态
，
并把所遇到的状态放入新创建的缓存
automaton_states

中。

9736

static
void

9737

add_automaton_state

(
state_t

state)
in
genautomata.c

9738

{

9739

VLA_PTR_ADD (automaton_states, state);

9740

}

在这之后，在
9763
行的
FOR

循环接着访问在
automaton_states

中的状态，如果从这个状态我们可以到达其它状态，我们就认为关联的指令是重要的。通过这个方式，我们过滤出单个迁移构成的封闭的环。

接着在
9783
行的
FOR

循环找出上面找到的包含重要
ainsn

的自动机。最后，这个自动机列表将被保存在
automata_list_table

中，这个表构建在
initiate_automata_lists

中。

然后在
expand_automata

的
9857
行，
make_internal_dfa_insn_code_attr

构建一个深度嵌套的条件表达式，它为所有的
define_insn_reservation
返回
insn_num
（模式的序列号，在
gen_insn_reserv

中产生），然后通过名字为“
*internal_dfa_insn_code
”的属性保存之。

9474

static
void

9475

make_internal_dfa_insn_code_attr

(void)
in
genautomata.c

9476

{

9477

int i, insn_num;

9478

decl_t

decl;

9479

rtx condexp;

9480

9481

condexp = rtx_alloc (COND);

9482

XVEC (condexp, 0) = rtvec_alloc ((description

->insns_num - 1) * 2);

9483

XEXP (condexp, 1)

9484

=
make_numeric_value

(DECL_INSN_RESERV
(advance_cycle_insn_decl

)

9485

->insn_num + 1);

9486

for
(i = insn_num = 0; i < description

->decls_num; i++)

9487

{

9488

decl = description

->decls [i];

9489

if (decl->mode == dm_insn_reserv
&& decl != advance_cycle_insn_decl

)

9490

{

9491

XVECEXP (condexp, 0, 2 * insn_num)

9492

= DECL_INSN_RESERV
(decl)->condexp;

9493

XVECEXP (condexp, 0, 2 * insn_num + 1)

9494

=
make_numeric_value

(DECL_INSN_RESERV (decl)->insn_num);

9495

insn_num++;

9496

}

9497

}

9498

if (description

->insns_num != insn_num + 1)

9499

abort ();

9500

make_internal_attr

9501

(attr_printf (sizeof ("*")

9502

+ strlen
(INTERNAL_DFA_INSN_CODE_FUNC_NAME) + 1,

9503

"*%s",
INTERNAL_DFA_INSN_CODE_FUNC_NAME),

9504

condexp, ATTR_STATIC);

9505

}

在上面的
9482
行，
description

的
insns_num

记录了
define_insn_reservation
，包括
advance_cycle_insn_decl

的数目（参考
process_decls

及
add_advance_cycle_insn_decl

）。而在
9486
行，
decls_num

记录了所有为自动机生成所构建的
decl
（参见
expand_automata

的
9818
行，及
add_advance_cycle_insn_decl

）。

接着在
expand_automata

的
9853
行，
make_insn_alts_attr

构建另一个深度嵌套的条件表达式，它返回特定指令的替代的数目，并通过名为“
*insn_alts
”的属性保存之。

9437

static
void

9438

make_insn_alts_attr

(void)
in
genautomata.c

9439

{

9440

int i, insn_num;

9441

decl_t decl;

9442

rtx condexp;

9443

9444

condexp = rtx_alloc (COND);

9445

XVEC (condexp, 0) = rtvec_alloc ((description

->insns_num - 1) * 2);

9446

XEXP (condexp, 1) = make_numeric_value (0);

9447

for
(i = insn_num = 0; i < description

->decls_num; i++)

9448

{

9449

decl = description

->decls [i];

9450

if (decl->mode == dm_insn_reserv
&& decl != advance_cycle_insn_decl

)

9451

{

9452

XVECEXP (condexp, 0, 2 * insn_num)

9453

= DECL_INSN_RESERV
(decl)->condexp;

9454

XVECEXP (condexp, 0, 2 * insn_num + 1)

9455

= make_numeric_value

9456

(DECL_INSN_RESERV
(decl)->transformed_regexp->mode != rm_oneof

9457

? 1 : REGEXP_ONEOF
(DECL_INSN_RESERV (decl)

9458

->transformed_regexp)->regexps_num);

9459

insn_num++;

9460

}

9461

}

9462

if (description

->insns_num != insn_num + 1)

9463

abort ();

9464

make_internal_attr

(attr_printf
(sizeof ("*")

9465

+ strlen (INSN_ALTS_FUNC_NAME) + 1,

9466

"*%s",
INSN_ALTS_FUNC_NAME),

9467

condexp, ATTR_NONE);

9468

}

接着在
expand_automata

的
9854
行，
make_default_insn_latency_attr

构建了另一个条件表达式，它返回指定指令的
default_latency
，并通过名为“
*insn_default_latency
”的属性保存之。

9511

static
void

9512

make_default_insn_latency_attr

(void)
in
genautomata.c

9513

{

9514

int i, insn_num;

9515

decl_t decl;

9516

rtx condexp;

9517

9518

condexp = rtx_alloc (COND);

9519

XVEC (condexp, 0) = rtvec_alloc ((description

->insns_num - 1) * 2);

9520

XEXP (condexp, 1) = make_numeric_value (0);

9521

for
(i = insn_num = 0; i < description

->decls_num; i++)

9522

{

9523

decl = description

->decls [i];

9524

if (decl->mode == dm_insn_reserv
&& decl != advance_cycle_insn_decl

)

9525

{

9526

XVECEXP (condexp, 0, 2 * insn_num)

9527

= DECL_INSN_RESERV
(decl)->condexp;

9528

XVECEXP (condexp, 0, 2 * insn_num + 1)

9529

= make_numeric_value
(DECL_INSN_RESERV (decl)->default_latency);

9530

insn_num++;

9531

}

9532

}

9533

if (description

->insns_num != insn_num + 1)

9534

abort ();

9535

make_internal_attr

(attr_printf
(sizeof ("*")

9536

+ strlen (INSN_DEFAULT_LATENCY_FUNC_NAME)

9537

+ 1, "*%s",
INSN_DEFAULT_LATENCY_FUNC_NAME),

9538

condexp, ATTR_NONE);

9539

}

而在
expand_automata

的
9855
行，
make_bypass_attr

计算指令列表的数目（参考
process_decls

的
2962
行），如果存在指令类别，构建一个向量，它保存具有
bypass_list
的指令类别中的条件部分，并通过名为“
*bypass_p
”的属性保存之。

9545

static
void

9546

make_bypass_attr

(void)
in
genautomata.c

9547

{

9548

int i, bypass_insn;

9549

int bypass_insns_num = 0;

9550

decl_t decl;

9551

rtx result_rtx;

9552

9553

for
(i = 0; i
< description

->decls_num;
i++)

9554

{

9555

decl = description

->decls [i];

9556

if (decl->mode == dm_insn_reserv

9557

&& DECL_INSN_RESERV
(decl)->condexp != NULL

9558

&& DECL_INSN_RESERV
(decl)->bypass_list != NULL)

9559

bypass_insns_num++;

9560

}

9561

if (bypass_insns_num == 0)

9562

result_rtx =
make_numeric_value

(0);

9563

else

9564

{

9565

result_rtx = rtx_alloc (COND);

9566

XVEC (result_rtx, 0) = rtvec_alloc
(bypass_insns_num * 2);

9567

XEXP

(result_rtx, 1) =
make_numeric_value

(0);

9568

9569

for
(i =
bypass_insn = 0; i < description

->decls_num; i++)

9570

{

9571

decl = description

->decls [i];

9572

if (decl->mode == dm_insn_reserv

9573

&& DECL_INSN_RESERV
(decl)->condexp != NULL

9574

&& DECL_INSN_RESERV
(decl)->bypass_list != NULL)

9575

{

9576

XVECEXP (result_rtx, 0, 2 *
bypass_insn)

9577

= DECL_INSN_RESERV
(decl)->condexp;

9578

XVECEXP (result_rtx, 0, 2 * bypass_insn
+ 1)

9579

=
make_numeric_value

(1);

9580

bypass_insn++;

9581

}

9582

}

9583

}

9584

make_internal_attr

(attr_printf
(sizeof ("*")

9585

+ strlen (BYPASS_P_FUNC_NAME)
+ 1,

9586

"*%s",
BYPASS_P_FUNC_NAME),

9587

result_rtx, ATTR_NONE);

9588

}