GCC后端及汇编发布（19）

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9.3.7. 读入DEFINE_BYPASS模式

DEFINE_INSN_RESERVATION模式的概览一节描述了define_bypass模式的细节。对于这个模式，我们使用以下的例子：

188 (define_bypass 0 "pent_push,pent_pop""pent_push,pent_pop,pent_call") in pentium.md

t44

图44：DEFINE_BYPASS模式的例子

这个模式是构建基于DFA识别器的流水线危险描述的一部分，该模式不应该与define_function_unit共存于同一个机器描述文件里。

在经过init_md_reader_args的处理后，上面的模式将作为上面的rtx对象载入内存。这里对define_bypass的处理类似于define_cup_unit。并且所构建的decl同样链入由decls所指向的链表。

1713 void

1714 gen_bypass (rtx def) ingenattrtab.c

1715 {

1716 decl_t decl;

1717 char **out_insns;

1718 int out_length;

1719 char **in_insns;

1720 int in_length;

1721 int i, j;

1722

1723 out_insns = get_str_vect ((char *) XSTR (def,1), &out_length, ',', FALSE);

1724 if (out_insns == NULL)

1725 fatal ("invalid string `%s' indefine_bypass", XSTR (def, 1));

1726 in_insns = get_str_vect ((char*) XSTR (def, 2), &in_length, ',', FALSE);

1727 if (in_insns == NULL)

1728 fatal ("invalid string `%s' indefine_bypass", XSTR (def, 2));

1729 for (i = 0; i< out_length; i++)

1730 for (j = 0;j < in_length; j++)

1731 {

1732 decl = create_node (sizeof (structdecl));

1733 decl->mode = dm_bypass;

1734 decl->pos = 0;

1735 DECL_BYPASS (decl)->latency = XINT (def, 0);

1736 DECL_BYPASS (decl)->out_insn_name = out_insns [i];

1737 DECL_BYPASS (decl)->in_insn_name = in_insns [j];

1738 DECL_BYPASS (decl)->bypass_guard_name = (char *) XSTR (def, 3);

1739 VLA_PTR_ADD (decls, decl);

1740 num_dfa_decls++;

1741 }

1742 }

上面，DECL_BYPASS访问decl的bypass域，它具有如下的定义：

788 struct bypass_decl ingenautomata.c

789 {

790 int latency;

791 char *out_insn_name;

792 char *in_insn_name;

793 char *bypass_guard_name;

794

795 /* The following fields are defined bychecker. */

796

797 /* output and input insns of givenbypass. */

798 struct insn_reserv_decl*out_insn_reserv;

799 struct insn_reserv_decl*in_insn_reserv;

800 /* The next bypass for given output insn. */

801 struct bypass_decl *next;

802 };

9.3.8. 读入EXCLUSION_SET模式

DEFINE_INSN_RESERVATION模式的概览一节描述了EXCLUSION_SET模式的细节。对于这个模式，我们使用以下的例子：

211 (exclusion_set "1_0m.ii" initanium.md

212 "1_0m.mi, 1_0m.fi, 1_0m.mf, 1_0b.bb, 1_0m.bb, 1_0m.ib,1_0m.mb, 1_0m.fb,/

213 1_0m.lx")

这个模式是构建基于DFA识别器的流水线危险描述的一部分，该模式不应该与define_function_unit共存于同一个机器描述文件里。

在经过init_md_reader_args的处理后，上面的模式将作为以下的rtx对象载入内存。这里对exclusion_set的处理类似于define_cup_unit。并且所构建的decl同样链入由decls所指向的链表。

t45

图45：EXCLUSION_SET模式的例子

1749 void

1750 gen_excl_set (rtx def) ingenattrtab.c

1751 {

1752 decl_t decl;

1753 char **first_str_cpu_units;

1754 char **second_str_cpu_units;

1755 int first_vect_length;

1756 int length;

1757 int i;

1758

1759 first_str_cpu_units

1760 = get_str_vect ((char *) XSTR (def, 0),&first_vect_length, ',', FALSE);

1761 if (first_str_cpu_units == NULL)

1762 fatal ("invalid first string `%s' inexclusion_set", XSTR (def, 0));

1763 second_str_cpu_units = get_str_vect ((char *)XSTR (def, 1), &length, ',',

1764 FALSE);

1765 if (second_str_cpu_units == NULL)

1766 fatal ("invalid second string `%s' inexclusion_set", XSTR (def, 1));

1767 length += first_vect_length;

1768 decl = create_node (sizeof(struct decl) + (length - 1) * sizeof (char *));

1769 decl->mode = dm_excl;

1770 decl->pos = 0;

1771 DECL_EXCL (decl)->all_names_num = length;

1772 DECL_EXCL (decl)->first_list_length = first_vect_length;

1773 for (i = 0; i< length; i++)

1774 if (i < first_vect_length)

1775 DECL_EXCL (decl)->names [i] = first_str_cpu_units [i];

1776 else

1777 DECL_EXCL (decl)->names [i]

1778 = second_str_cpu_units [i -first_vect_length];

1779 VLA_PTR_ADD(decls,decl);

1780 num_dfa_decls++;

1781 }

DECL_EXCL访问decl的excl_rel_decl域。excl_rel_decl具有如下定义，看到names域实际上是可变长度数组，其元素对应单元名。

826 struct excl_rel_decl ingenautomata.c

827 {

828 int all_names_num;

829 int first_list_length;

830 char *names [1];

831 };

前面看过，模式PRESENCE_SET，FINAL_PRESENCE_SET，ABSENCE_SET及FINAL_ABSENCE_SET使用相同的格式，因此它们的处理是类似的。

下面的函数处理PRESENCE_SET，FINAL_PRESENCE_SET，ABSENCE_SET及FINAL_ABSENCE_SET。

1857 void

1858 gen_presence_set (rtx def) ingenautomata.c

1859 {

1860 gen_presence_absence_set (def, TRUE,FALSE);

1861 }

1868 void

1869 gen_final_presence_set (rtx def) ingenautomata.c

1870 {

1871 gen_presence_absence_set (def, TRUE,TRUE);

1872 }

1879 void

1880 gen_absence_set (rtx def) ingenautomata.c

1881 {

1882 gen_presence_absence_set (def, FALSE,FALSE);

1883 }

1890 void

1891 gen_final_absence_set (rtx def) ingenautomata.c

1892 {

1893 gen_presence_absence_set (def,TRUE, TRUE);

1894 }

注意对于exclude_set之外，其它模式的第二个操作数都是‘PATTERNS’，即功能单元模式列表，每个功能单元模式是一个单元或由空格分隔的多个单元（exclude_set中则是‘UNIT-NAMES’，即单元列表）。

1789 static void

1790 gen_presence_absence_set (rtx def, intpresence_p, int final_p) in genautomata.c

1791 {

1792 decl_t decl;

1793 char **str_cpu_units;

1794 char ***str_patterns;

1795 int cpu_units_length;

1796 int length;

1797 int patterns_length;

1798 int i;

1799

1800 str_cpu_units = get_str_vect ((char *) XSTR(def, 0), &cpu_units_length, ',',

1801 FALSE);

1802 if (str_cpu_units == NULL)

1803 fatal ((presence_p

1804 ?(final_p

1805 ?"invalid first string `%s' in final_presence_set"

1806 : "invalid first string `%s' inpresence_set")

1807 :(final_p

1808 ? "invalid first string `%s' infinal_absence_set"

1809 : "invalid first string `%s' inabsence_set")),

1810 XSTR(def, 0));

1811 str_patterns = (char ***) get_str_vect ((char*) XSTR (def, 1),

1812 &patterns_length,',', FALSE);

1813 if (str_patterns == NULL)

1814 fatal ((presence_p

1815 ?(final_p

1816 ? "invalid second string `%s' infinal_presence_set"

1817 : "invalid second string `%s' inpresence_set")

1818 :(final_p

1819 ? "invalid second string `%s' infinal_absence_set"

1820 : "invalid second string `%s' inabsence_set")), XSTR (def, 1));

1821 for (i = 0; i< patterns_length; i++)

1822 {

1823 str_patterns [i] = get_str_vect ((char *)str_patterns [i], &length, ' ',

1824 FALSE);

1825 if (str_patterns [i] == NULL)

1826 abort ();

1827 }

1828 decl = create_node (sizeof(struct decl));

1829 decl->pos = 0;

1830 if (presence_p)

1831 {

1832 decl->mode = dm_presence;

1833 DECL_PRESENCE (decl)->names_num =cpu_units_length;

1834 DECL_PRESENCE (decl)->names =str_cpu_units;

1835 DECL_PRESENCE (decl)->patterns =str_patterns;

1836 DECL_PRESENCE (decl)->patterns_num= patterns_length;

1837 DECL_PRESENCE (decl)->final_p = final_p;

1838 }

1839 else

1840 {

1841 decl->mode = dm_absence;

1842 DECL_ABSENCE (decl)->names_num =cpu_units_length;

1843 DECL_ABSENCE (decl)->names =str_cpu_units;

1844 DECL_ABSENCE (decl)->patterns =str_patterns;

1845 DECL_ABSENCE (decl)->patterns_num= patterns_length;

1846 DECL_ABSENCE (decl)->final_p = final_p;

1847 }

1848 VLA_PTR_ADD (decls, decl);

1849 num_dfa_decls++;

1850 }

DECL_PRESENT访问decl的presence域，而DECL_ABSENT访问decl的absence域。两者都具有类型unit_pattern_rel_decl。

835 struct unit_pattern_rel_decl ingenautomata.c

836 {

837 int final_p;

838 int names_num;

839 int patterns_num;

840 char **names;

841 char ***patterns;

842 };

9.3.9. 读入DEFINE_AUTOMATON模式

DEFINE_INSN_RESERVATION模式的概览一节描述了DEFINE_AUTOMATON模式的细节。对于这个模式，我们使用以下例子：

71 (define_automaton "pentium,pentium_fpu") in pentium.md

这个模式是构建基于DFA识别器的流水线危险描述的一部分，该模式不应该与define_function_unit共存于同一个机器描述文件里。

在经过init_md_reader_args的处理后，上面的模式将作为以下的rtx对象载入内存。

t46

图46：DEFINE_AUTOMATON模式的例子

我们需要把这个rtx对象通过gen_automaton转换为decl_t对象。

1901 void

1902 gen_automaton (rtx def) ingenautomata.c

1903 {

1904 decl_t decl;

1905 char **str_automata;

1906 int vect_length;

1907 int i;

1908

1909 str_automata = get_str_vect ((char *) XSTR(def, 0), &vect_length, ',',

1910 FALSE);

1911 if (str_automata == NULL)

1912 fatal ("invalid string `%s' indefine_automaton", XSTR (def, 0));

1913 for (i = 0; i< vect_length; i++)

1914 {

1915 decl = create_node (sizeof (struct decl));

1916 decl->mode = dm_automaton;

1917 decl->pos = 0;

1918 DECL_AUTOMATON (decl)->name = check_name (str_automata [i], decl->pos);

1919 VLA_PTR_ADD (decls, decl);

1920 num_dfa_decls++;

1921 }

1922 }

DECL_AUTOMATON访问decl的automaton域，这个域具有如下的定义。

803 struct automaton_decl ingenautomata.c

804 {

805 char *name;

806

807 /* The following fields are defined byautomaton generator. */

808

809 /* The following field value is nonzero if theautomaton is used in

810 an regexp definition. */

811 char automaton_is_used;

812

813 /* The following fields are defined bychecker. */

814

815 /* The following field value is thecorresponding automaton. This

816 field is not NULL only if the automaton ispresent in unit

817 declarations and the automatic partition onautomata is not

818 used. */

819 automaton_t corresponding_automaton;

820 };

automaton_t域指向后面所构建的automaton对象。我们将在后面看到它。

9.3.10. 读入AUTOMATA_OPTION模式

As we see before, we can use AUTOMATA_OPTION pattern to instruct theautomaton generation.

1928 void

1929 gen_automata_option (rtx def) ingenautomata.c

1930 {

1931 if (strcmp (XSTR (def, 0),NO_MINIMIZATION_OPTION + 1) == 0)

1932 no_minimization_flag = 1;

1933 else if (strcmp (XSTR (def, 0), TIME_OPTION +1) == 0)

1934 time_flag= 1;

1935 else if (strcmp (XSTR (def, 0), V_OPTION + 1)== 0)

1936 v_flag = 1;

1937 else if (strcmp (XSTR (def, 0), W_OPTION + 1)== 0)

1938 w_flag = 1;

1939 else if (strcmp (XSTR (def, 0), NDFA_OPTION +1) == 0)

1940 ndfa_flag = 1;

1941 else if (strcmp (XSTR (def, 0),PROGRESS_OPTION + 1) == 0)

1942 progress_flag = 1;

1943 else

1944 fatal ("invalid option `%s' inautomata_option", XSTR (def, 0));

1945 }

这个模式是构建基于DFA识别器的流水线危险描述的一部分，该模式不应该与define_function_unit共存于同一个机器描述文件里。

注意为了指明多个选项，应该使用多个AUTOMATA_OPTION模式。