1 @c Copyright (C) 1991-2016 Free Software Foundation, Inc. 2 @c This is part of the GAS manual. 3 @c For copying conditions, see the file as.texinfo. 4 @page 5 @node HPPA-Dependent 6 @chapter HPPA Dependent Features 7 8 @cindex support 9 @menu 10 * HPPA Notes:: Notes 11 * HPPA Options:: Options 12 * HPPA Syntax:: Syntax 13 * HPPA Floating Point:: Floating Point 14 * HPPA Directives:: HPPA Machine Directives 15 * HPPA Opcodes:: Opcodes 16 @end menu 17 18 @node HPPA Notes 19 @section Notes 20 As a back end for @sc{gnu} @sc{cc} @code{@value{AS}} has been throughly tested and should 21 work extremely well. We have tested it only minimally on hand written assembly 22 code and no one has tested it much on the assembly output from the HP 23 compilers. 24 25 The format of the debugging sections has changed since the original 26 @code{@value{AS}} port (version 1.3X) was released; therefore, 27 you must rebuild all HPPA objects and libraries with the new 28 assembler so that you can debug the final executable. 29 30 The HPPA @code{@value{AS}} port generates a small subset of the relocations 31 available in the SOM and ELF object file formats. Additional relocation 32 support will be added as it becomes necessary. 33 34 @node HPPA Options 35 @section Options 36 @code{@value{AS}} has no machine-dependent command-line options for the HPPA. 37 38 @cindex HPPA Syntax 39 @node HPPA Syntax 40 @section Syntax 41 The assembler syntax closely follows the HPPA instruction set 42 reference manual; assembler directives and general syntax closely follow the 43 HPPA assembly language reference manual, with a few noteworthy differences. 44 45 First, a colon may immediately follow a label definition. This is 46 simply for compatibility with how most assembly language programmers 47 write code. 48 49 Some obscure expression parsing problems may affect hand written code which 50 uses the @code{spop} instructions, or code which makes significant 51 use of the @code{!} line separator. 52 53 @code{@value{AS}} is much less forgiving about missing arguments and other 54 similar oversights than the HP assembler. @code{@value{AS}} notifies you 55 of missing arguments as syntax errors; this is regarded as a feature, not a 56 bug. 57 58 Finally, @code{@value{AS}} allows you to use an external symbol without 59 explicitly importing the symbol. @emph{Warning:} in the future this will be 60 an error for HPPA targets. 61 62 Special characters for HPPA targets include: 63 64 @samp{;} is the line comment character. 65 66 @samp{!} can be used instead of a newline to separate statements. 67 68 Since @samp{$} has no special meaning, you may use it in symbol names. 69 70 @node HPPA Floating Point 71 @section Floating Point 72 @cindex floating point, HPPA (@sc{ieee}) 73 @cindex HPPA floating point (@sc{ieee}) 74 The HPPA family uses @sc{ieee} floating-point numbers. 75 76 @node HPPA Directives 77 @section HPPA Assembler Directives 78 79 @code{@value{AS}} for the HPPA supports many additional directives for 80 compatibility with the native assembler. This section describes them only 81 briefly. For detailed information on HPPA-specific assembler directives, see 82 @cite{HP9000 Series 800 Assembly Language Reference Manual} (HP 92432-90001). 83 84 @cindex HPPA directives not supported 85 @code{@value{AS}} does @emph{not} support the following assembler directives 86 described in the HP manual: 87 88 @example 89 .endm .liston 90 .enter .locct 91 .leave .macro 92 .listoff 93 @end example 94 95 @cindex @code{.param} on HPPA 96 Beyond those implemented for compatibility, @code{@value{AS}} supports one 97 additional assembler directive for the HPPA: @code{.param}. It conveys 98 register argument locations for static functions. Its syntax closely follows 99 the @code{.export} directive. 100 101 @cindex HPPA-only directives 102 These are the additional directives in @code{@value{AS}} for the HPPA: 103 104 @table @code 105 @item .block @var{n} 106 @itemx .blockz @var{n} 107 Reserve @var{n} bytes of storage, and initialize them to zero. 108 109 @item .call 110 Mark the beginning of a procedure call. Only the special case with @emph{no 111 arguments} is allowed. 112 113 @item .callinfo [ @var{param}=@var{value}, @dots{} ] [ @var{flag}, @dots{} ] 114 Specify a number of parameters and flags that define the environment for a 115 procedure. 116 117 @var{param} may be any of @samp{frame} (frame size), @samp{entry_gr} (end of 118 general register range), @samp{entry_fr} (end of float register range), 119 @samp{entry_sr} (end of space register range). 120 121 The values for @var{flag} are @samp{calls} or @samp{caller} (proc has 122 subroutines), @samp{no_calls} (proc does not call subroutines), @samp{save_rp} 123 (preserve return pointer), @samp{save_sp} (proc preserves stack pointer), 124 @samp{no_unwind} (do not unwind this proc), @samp{hpux_int} (proc is interrupt 125 routine). 126 127 @item .code 128 Assemble into the standard section called @samp{$TEXT$}, subsection 129 @samp{$CODE$}. 130 131 @ifset SOM 132 @item .copyright "@var{string}" 133 In the SOM object format, insert @var{string} into the object code, marked as a 134 copyright string. 135 @end ifset 136 137 @ifset ELF 138 @item .copyright "@var{string}" 139 In the ELF object format, insert @var{string} into the object code, marked as a 140 version string. 141 @end ifset 142 143 @item .enter 144 Not yet supported; the assembler rejects programs containing this directive. 145 146 @item .entry 147 Mark the beginning of a procedure. 148 149 @item .exit 150 Mark the end of a procedure. 151 152 @item .export @var{name} [ ,@var{typ} ] [ ,@var{param}=@var{r} ] 153 Make a procedure @var{name} available to callers. @var{typ}, if present, must 154 be one of @samp{absolute}, @samp{code} (ELF only, not SOM), @samp{data}, 155 @samp{entry}, @samp{data}, @samp{entry}, @samp{millicode}, @samp{plabel}, 156 @samp{pri_prog}, or @samp{sec_prog}. 157 158 @var{param}, if present, provides either relocation information for the 159 procedure arguments and result, or a privilege level. @var{param} may be 160 @samp{argw@var{n}} (where @var{n} ranges from @code{0} to @code{3}, and 161 indicates one of four one-word arguments); @samp{rtnval} (the procedure's 162 result); or @samp{priv_lev} (privilege level). For arguments or the result, 163 @var{r} specifies how to relocate, and must be one of @samp{no} (not 164 relocatable), @samp{gr} (argument is in general register), @samp{fr} (in 165 floating point register), or @samp{fu} (upper half of float register). 166 For @samp{priv_lev}, @var{r} is an integer. 167 168 @item .half @var{n} 169 Define a two-byte integer constant @var{n}; synonym for the portable 170 @code{@value{AS}} directive @code{.short}. 171 172 @item .import @var{name} [ ,@var{typ} ] 173 Converse of @code{.export}; make a procedure available to call. The arguments 174 use the same conventions as the first two arguments for @code{.export}. 175 176 @item .label @var{name} 177 Define @var{name} as a label for the current assembly location. 178 179 @item .leave 180 Not yet supported; the assembler rejects programs containing this directive. 181 182 @item .origin @var{lc} 183 Advance location counter to @var{lc}. Synonym for the @code{@value{AS}} 184 portable directive @code{.org}. 185 186 @item .param @var{name} [ ,@var{typ} ] [ ,@var{param}=@var{r} ] 187 @c Not in HP manual; @sc{gnu} HPPA extension 188 Similar to @code{.export}, but used for static procedures. 189 190 @item .proc 191 Use preceding the first statement of a procedure. 192 193 @item .procend 194 Use following the last statement of a procedure. 195 196 @item @var{label} .reg @var{expr} 197 @c ?? Not in HP manual (Jan 1988 vn) 198 Synonym for @code{.equ}; define @var{label} with the absolute expression 199 @var{expr} as its value. 200 201 @item .space @var{secname} [ ,@var{params} ] 202 Switch to section @var{secname}, creating a new section by that name if 203 necessary. You may only use @var{params} when creating a new section, not 204 when switching to an existing one. @var{secname} may identify a section by 205 number rather than by name. 206 207 If specified, the list @var{params} declares attributes of the section, 208 identified by keywords. The keywords recognized are @samp{spnum=@var{exp}} 209 (identify this section by the number @var{exp}, an absolute expression), 210 @samp{sort=@var{exp}} (order sections according to this sort key when linking; 211 @var{exp} is an absolute expression), @samp{unloadable} (section contains no 212 loadable data), @samp{notdefined} (this section defined elsewhere), and 213 @samp{private} (data in this section not available to other programs). 214 215 @item .spnum @var{secnam} 216 @c ?? Not in HP manual (Jan 1988) 217 Allocate four bytes of storage, and initialize them with the section number of 218 the section named @var{secnam}. (You can define the section number with the 219 HPPA @code{.space} directive.) 220 221 @cindex @code{string} directive on HPPA 222 @item .string "@var{str}" 223 Copy the characters in the string @var{str} to the object file. 224 @xref{Strings,,Strings}, for information on escape sequences you can use in 225 @code{@value{AS}} strings. 226 227 @emph{Warning!} The HPPA version of @code{.string} differs from the 228 usual @code{@value{AS}} definition: it does @emph{not} write a zero byte 229 after copying @var{str}. 230 231 @item .stringz "@var{str}" 232 Like @code{.string}, but appends a zero byte after copying @var{str} to object 233 file. 234 235 @item .subspa @var{name} [ ,@var{params} ] 236 @itemx .nsubspa @var{name} [ ,@var{params} ] 237 Similar to @code{.space}, but selects a subsection @var{name} within the 238 current section. You may only specify @var{params} when you create a 239 subsection (in the first instance of @code{.subspa} for this @var{name}). 240 241 If specified, the list @var{params} declares attributes of the subsection, 242 identified by keywords. The keywords recognized are @samp{quad=@var{expr}} 243 (``quadrant'' for this subsection), @samp{align=@var{expr}} (alignment for 244 beginning of this subsection; a power of two), @samp{access=@var{expr}} (value 245 for ``access rights'' field), @samp{sort=@var{expr}} (sorting order for this 246 subspace in link), @samp{code_only} (subsection contains only code), 247 @samp{unloadable} (subsection cannot be loaded into memory), @samp{comdat} 248 (subsection is comdat), @samp{common} (subsection is common block), 249 @samp{dup_comm} (subsection may have duplicate names), or @samp{zero} 250 (subsection is all zeros, do not write in object file). 251 252 @code{.nsubspa} always creates a new subspace with the given name, even 253 if one with the same name already exists. 254 255 @samp{comdat}, @samp{common} and @samp{dup_comm} can be used to implement 256 various flavors of one-only support when using the SOM linker. The SOM 257 linker only supports specific combinations of these flags. The details 258 are not documented. A brief description is provided here. 259 260 @samp{comdat} provides a form of linkonce support. It is useful for 261 both code and data subspaces. A @samp{comdat} subspace has a key symbol 262 marked by the @samp{is_comdat} flag or @samp{ST_COMDAT}. Only the first 263 subspace for any given key is selected. The key symbol becomes universal 264 in shared links. This is similar to the behavior of @samp{secondary_def} 265 symbols. 266 267 @samp{common} provides Fortran named common support. It is only useful 268 for data subspaces. Symbols with the flag @samp{is_common} retain this 269 flag in shared links. Referencing a @samp{is_common} symbol in a shared 270 library from outside the library doesn't work. Thus, @samp{is_common} 271 symbols must be output whenever they are needed. 272 273 @samp{common} and @samp{dup_comm} together provide Cobol common support. 274 The subspaces in this case must all be the same length. Otherwise, this 275 support is similar to the Fortran common support. 276 277 @samp{dup_comm} by itself provides a type of one-only support for code. 278 Only the first @samp{dup_comm} subspace is selected. There is a rather 279 complex algorithm to compare subspaces. Code symbols marked with the 280 @samp{dup_common} flag are hidden. This support was intended for "C++ 281 duplicate inlines". 282 283 A simplified technique is used to mark the flags of symbols based on 284 the flags of their subspace. A symbol with the scope SS_UNIVERSAL and 285 type ST_ENTRY, ST_CODE or ST_DATA is marked with the corresponding 286 settings of @samp{comdat}, @samp{common} and @samp{dup_comm} from the 287 subspace, respectively. This avoids having to introduce additional 288 directives to mark these symbols. The HP assembler sets @samp{is_common} 289 from @samp{common}. However, it doesn't set the @samp{dup_common} from 290 @samp{dup_comm}. It doesn't have @samp{comdat} support. 291 292 @item .version "@var{str}" 293 Write @var{str} as version identifier in object code. 294 @end table 295 296 @node HPPA Opcodes 297 @section Opcodes 298 For detailed information on the HPPA machine instruction set, see 299 @cite{PA-RISC Architecture and Instruction Set Reference Manual} 300 (HP 09740-90039). 301
