Commit | Line | Data |
---|---|---|
84c84759 | 1 | @c Copyright 1991, 1992, 1993, 1994, 1995, 1998, 2004 |
f7e42eb4 | 2 | @c Free Software Foundation, Inc. |
252b5132 RH |
3 | @c This is part of the GAS manual. |
4 | @c For copying conditions, see the file as.texinfo. | |
5 | @page | |
6 | @node HPPA-Dependent | |
7 | @chapter HPPA Dependent Features | |
8 | ||
9 | @cindex support | |
10 | @menu | |
11 | * HPPA Notes:: Notes | |
12 | * HPPA Options:: Options | |
13 | * HPPA Syntax:: Syntax | |
14 | * HPPA Floating Point:: Floating Point | |
15 | * HPPA Directives:: HPPA Machine Directives | |
16 | * HPPA Opcodes:: Opcodes | |
17 | @end menu | |
18 | ||
19 | @node HPPA Notes | |
20 | @section Notes | |
21 | As a back end for @sc{gnu} @sc{cc} @code{@value{AS}} has been throughly tested and should | |
22 | work extremely well. We have tested it only minimally on hand written assembly | |
23 | code and no one has tested it much on the assembly output from the HP | |
24 | compilers. | |
25 | ||
26 | The format of the debugging sections has changed since the original | |
27 | @code{@value{AS}} port (version 1.3X) was released; therefore, | |
28 | you must rebuild all HPPA objects and libraries with the new | |
29 | assembler so that you can debug the final executable. | |
30 | ||
31 | The HPPA @code{@value{AS}} port generates a small subset of the relocations | |
32 | available in the SOM and ELF object file formats. Additional relocation | |
33 | support will be added as it becomes necessary. | |
34 | ||
35 | @node HPPA Options | |
36 | @section Options | |
37 | @code{@value{AS}} has no machine-dependent command-line options for the HPPA. | |
38 | ||
39 | @cindex HPPA Syntax | |
40 | @node HPPA Syntax | |
41 | @section Syntax | |
42 | The assembler syntax closely follows the HPPA instruction set | |
43 | reference manual; assembler directives and general syntax closely follow the | |
44 | HPPA assembly language reference manual, with a few noteworthy differences. | |
45 | ||
46 | First, a colon may immediately follow a label definition. This is | |
47 | simply for compatibility with how most assembly language programmers | |
48 | write code. | |
49 | ||
50 | Some obscure expression parsing problems may affect hand written code which | |
51 | uses the @code{spop} instructions, or code which makes significant | |
52 | use of the @code{!} line separator. | |
53 | ||
54 | @code{@value{AS}} is much less forgiving about missing arguments and other | |
55 | similar oversights than the HP assembler. @code{@value{AS}} notifies you | |
56 | of missing arguments as syntax errors; this is regarded as a feature, not a | |
57 | bug. | |
58 | ||
59 | Finally, @code{@value{AS}} allows you to use an external symbol without | |
60 | explicitly importing the symbol. @emph{Warning:} in the future this will be | |
61 | an error for HPPA targets. | |
62 | ||
63 | Special characters for HPPA targets include: | |
64 | ||
65 | @samp{;} is the line comment character. | |
66 | ||
67 | @samp{!} can be used instead of a newline to separate statements. | |
68 | ||
69 | Since @samp{$} has no special meaning, you may use it in symbol names. | |
70 | ||
71 | @node HPPA Floating Point | |
72 | @section Floating Point | |
73 | @cindex floating point, HPPA (@sc{ieee}) | |
74 | @cindex HPPA floating point (@sc{ieee}) | |
75 | The HPPA family uses @sc{ieee} floating-point numbers. | |
76 | ||
77 | @node HPPA Directives | |
78 | @section HPPA Assembler Directives | |
79 | ||
80 | @code{@value{AS}} for the HPPA supports many additional directives for | |
81 | compatibility with the native assembler. This section describes them only | |
82 | briefly. For detailed information on HPPA-specific assembler directives, see | |
83 | @cite{HP9000 Series 800 Assembly Language Reference Manual} (HP 92432-90001). | |
84 | ||
85 | @cindex HPPA directives not supported | |
86 | @code{@value{AS}} does @emph{not} support the following assembler directives | |
87 | described in the HP manual: | |
88 | ||
89 | @example | |
90 | .endm .liston | |
91 | .enter .locct | |
92 | .leave .macro | |
93 | .listoff | |
94 | @end example | |
95 | ||
96 | @cindex @code{.param} on HPPA | |
97 | Beyond those implemented for compatibility, @code{@value{AS}} supports one | |
98 | additional assembler directive for the HPPA: @code{.param}. It conveys | |
99 | register argument locations for static functions. Its syntax closely follows | |
100 | the @code{.export} directive. | |
101 | ||
102 | @cindex HPPA-only directives | |
103 | These are the additional directives in @code{@value{AS}} for the HPPA: | |
104 | ||
105 | @table @code | |
106 | @item .block @var{n} | |
107 | @itemx .blockz @var{n} | |
108 | Reserve @var{n} bytes of storage, and initialize them to zero. | |
109 | ||
110 | @item .call | |
111 | Mark the beginning of a procedure call. Only the special case with @emph{no | |
112 | arguments} is allowed. | |
113 | ||
114 | @item .callinfo [ @var{param}=@var{value}, @dots{} ] [ @var{flag}, @dots{} ] | |
115 | Specify a number of parameters and flags that define the environment for a | |
116 | procedure. | |
117 | ||
118 | @var{param} may be any of @samp{frame} (frame size), @samp{entry_gr} (end of | |
119 | general register range), @samp{entry_fr} (end of float register range), | |
120 | @samp{entry_sr} (end of space register range). | |
121 | ||
122 | The values for @var{flag} are @samp{calls} or @samp{caller} (proc has | |
123 | subroutines), @samp{no_calls} (proc does not call subroutines), @samp{save_rp} | |
124 | (preserve return pointer), @samp{save_sp} (proc preserves stack pointer), | |
125 | @samp{no_unwind} (do not unwind this proc), @samp{hpux_int} (proc is interrupt | |
126 | routine). | |
127 | ||
128 | @item .code | |
129 | Assemble into the standard section called @samp{$TEXT$}, subsection | |
130 | @samp{$CODE$}. | |
131 | ||
132 | @ifset SOM | |
133 | @item .copyright "@var{string}" | |
134 | In the SOM object format, insert @var{string} into the object code, marked as a | |
135 | copyright string. | |
136 | @end ifset | |
137 | ||
138 | @ifset ELF | |
139 | @item .copyright "@var{string}" | |
140 | In the ELF object format, insert @var{string} into the object code, marked as a | |
141 | version string. | |
142 | @end ifset | |
143 | ||
144 | @item .enter | |
145 | Not yet supported; the assembler rejects programs containing this directive. | |
146 | ||
147 | @item .entry | |
148 | Mark the beginning of a procedure. | |
149 | ||
150 | @item .exit | |
151 | Mark the end of a procedure. | |
152 | ||
153 | @item .export @var{name} [ ,@var{typ} ] [ ,@var{param}=@var{r} ] | |
154 | Make a procedure @var{name} available to callers. @var{typ}, if present, must | |
155 | be one of @samp{absolute}, @samp{code} (ELF only, not SOM), @samp{data}, | |
156 | @samp{entry}, @samp{data}, @samp{entry}, @samp{millicode}, @samp{plabel}, | |
157 | @samp{pri_prog}, or @samp{sec_prog}. | |
158 | ||
159 | @var{param}, if present, provides either relocation information for the | |
160 | procedure arguments and result, or a privilege level. @var{param} may be | |
161 | @samp{argw@var{n}} (where @var{n} ranges from @code{0} to @code{3}, and | |
162 | indicates one of four one-word arguments); @samp{rtnval} (the procedure's | |
163 | result); or @samp{priv_lev} (privilege level). For arguments or the result, | |
164 | @var{r} specifies how to relocate, and must be one of @samp{no} (not | |
165 | relocatable), @samp{gr} (argument is in general register), @samp{fr} (in | |
166 | floating point register), or @samp{fu} (upper half of float register). | |
167 | For @samp{priv_lev}, @var{r} is an integer. | |
168 | ||
169 | @item .half @var{n} | |
170 | Define a two-byte integer constant @var{n}; synonym for the portable | |
171 | @code{@value{AS}} directive @code{.short}. | |
172 | ||
173 | @item .import @var{name} [ ,@var{typ} ] | |
174 | Converse of @code{.export}; make a procedure available to call. The arguments | |
175 | use the same conventions as the first two arguments for @code{.export}. | |
176 | ||
177 | @item .label @var{name} | |
178 | Define @var{name} as a label for the current assembly location. | |
179 | ||
180 | @item .leave | |
181 | Not yet supported; the assembler rejects programs containing this directive. | |
182 | ||
183 | @item .origin @var{lc} | |
84c84759 | 184 | Advance location counter to @var{lc}. Synonym for the @code{@value{AS}} |
252b5132 RH |
185 | portable directive @code{.org}. |
186 | ||
187 | @item .param @var{name} [ ,@var{typ} ] [ ,@var{param}=@var{r} ] | |
188 | @c Not in HP manual; @sc{gnu} HPPA extension | |
189 | Similar to @code{.export}, but used for static procedures. | |
190 | ||
191 | @item .proc | |
192 | Use preceding the first statement of a procedure. | |
193 | ||
194 | @item .procend | |
195 | Use following the last statement of a procedure. | |
196 | ||
197 | @item @var{label} .reg @var{expr} | |
198 | @c ?? Not in HP manual (Jan 1988 vn) | |
199 | Synonym for @code{.equ}; define @var{label} with the absolute expression | |
200 | @var{expr} as its value. | |
201 | ||
202 | @item .space @var{secname} [ ,@var{params} ] | |
203 | Switch to section @var{secname}, creating a new section by that name if | |
204 | necessary. You may only use @var{params} when creating a new section, not | |
205 | when switching to an existing one. @var{secname} may identify a section by | |
206 | number rather than by name. | |
207 | ||
208 | If specified, the list @var{params} declares attributes of the section, | |
209 | identified by keywords. The keywords recognized are @samp{spnum=@var{exp}} | |
210 | (identify this section by the number @var{exp}, an absolute expression), | |
211 | @samp{sort=@var{exp}} (order sections according to this sort key when linking; | |
212 | @var{exp} is an absolute expression), @samp{unloadable} (section contains no | |
213 | loadable data), @samp{notdefined} (this section defined elsewhere), and | |
214 | @samp{private} (data in this section not available to other programs). | |
215 | ||
216 | @item .spnum @var{secnam} | |
217 | @c ?? Not in HP manual (Jan 1988) | |
218 | Allocate four bytes of storage, and initialize them with the section number of | |
219 | the section named @var{secnam}. (You can define the section number with the | |
220 | HPPA @code{.space} directive.) | |
221 | ||
222 | @cindex @code{string} directive on HPPA | |
223 | @item .string "@var{str}" | |
224 | Copy the characters in the string @var{str} to the object file. | |
225 | @xref{Strings,,Strings}, for information on escape sequences you can use in | |
226 | @code{@value{AS}} strings. | |
227 | ||
228 | @emph{Warning!} The HPPA version of @code{.string} differs from the | |
229 | usual @code{@value{AS}} definition: it does @emph{not} write a zero byte | |
230 | after copying @var{str}. | |
231 | ||
232 | @item .stringz "@var{str}" | |
233 | Like @code{.string}, but appends a zero byte after copying @var{str} to object | |
234 | file. | |
235 | ||
236 | @item .subspa @var{name} [ ,@var{params} ] | |
237 | @itemx .nsubspa @var{name} [ ,@var{params} ] | |
238 | Similar to @code{.space}, but selects a subsection @var{name} within the | |
239 | current section. You may only specify @var{params} when you create a | |
240 | subsection (in the first instance of @code{.subspa} for this @var{name}). | |
241 | ||
242 | If specified, the list @var{params} declares attributes of the subsection, | |
243 | identified by keywords. The keywords recognized are @samp{quad=@var{expr}} | |
244 | (``quadrant'' for this subsection), @samp{align=@var{expr}} (alignment for | |
245 | beginning of this subsection; a power of two), @samp{access=@var{expr}} (value | |
246 | for ``access rights'' field), @samp{sort=@var{expr}} (sorting order for this | |
247 | subspace in link), @samp{code_only} (subsection contains only code), | |
351e2b5a DA |
248 | @samp{unloadable} (subsection cannot be loaded into memory), @samp{comdat} |
249 | (subsection is comdat), @samp{common} (subsection is common block), | |
250 | @samp{dup_comm} (subsection may have duplicate names), or @samp{zero} | |
251 | (subsection is all zeros, do not write in object file). | |
252b5132 RH |
252 | |
253 | @code{.nsubspa} always creates a new subspace with the given name, even | |
254 | if one with the same name already exists. | |
255 | ||
351e2b5a DA |
256 | @samp{comdat}, @samp{common} and @samp{dup_comm} can be used to implement |
257 | various flavors of one-only support when using the SOM linker. The SOM | |
258 | linker only supports specific combinations of these flags. The details | |
259 | are not documented. A brief description is provided here. | |
260 | ||
261 | @samp{comdat} provides a form of linkonce support. It is useful for | |
262 | both code and data subspaces. A @samp{comdat} subspace has a key symbol | |
263 | marked by the @samp{is_comdat} flag or @samp{ST_COMDAT}. Only the first | |
264 | subspace for any given key is selected. The key symbol becomes universal | |
265 | in shared links. This is similar to the behavior of @samp{secondary_def} | |
266 | symbols. | |
267 | ||
268 | @samp{common} provides Fortran named common support. It is only useful | |
269 | for data subspaces. Symbols with the flag @samp{is_common} retain this | |
270 | flag in shared links. Referencing a @samp{is_common} symbol in a shared | |
271 | library from outside the library doesn't work. Thus, @samp{is_common} | |
272 | symbols must be output whenever they are needed. | |
273 | ||
274 | @samp{common} and @samp{dup_comm} together provide Cobol common support. | |
275 | The subspaces in this case must all be the same length. Otherwise, this | |
276 | support is similar to the Fortran common support. | |
277 | ||
278 | @samp{dup_comm} by itself provides a type of one-only support for code. | |
279 | Only the first @samp{dup_comm} subspace is selected. There is a rather | |
280 | complex algorithm to compare subspaces. Code symbols marked with the | |
281 | @samp{dup_common} flag are hidden. This support was intended for "C++ | |
282 | duplicate inlines". | |
283 | ||
284 | A simplified technique is used to mark the flags of symbols based on | |
285 | the flags of their subspace. A symbol with the scope SS_UNIVERSAL and | |
286 | type ST_ENTRY, ST_CODE or ST_DATA is marked with the corresponding | |
287 | settings of @samp{comdat}, @samp{common} and @samp{dup_comm} from the | |
288 | subspace, respectively. This avoids having to introduce additional | |
289 | directives to mark these symbols. The HP assembler sets @samp{is_common} | |
290 | from @samp{common}. However, it doesn't set the @samp{dup_common} from | |
291 | @samp{dup_comm}. It doesn't have @samp{comdat} support. | |
292 | ||
252b5132 RH |
293 | @item .version "@var{str}" |
294 | Write @var{str} as version identifier in object code. | |
295 | @end table | |
296 | ||
297 | @node HPPA Opcodes | |
298 | @section Opcodes | |
299 | For detailed information on the HPPA machine instruction set, see | |
300 | @cite{PA-RISC Architecture and Instruction Set Reference Manual} | |
301 | (HP 09740-90039). |