-@c Copyright (C) 1991, 1992, 1993, 1994, 1995 Free Software Foundation, Inc.
+@c Copyright (C) 1991-2019 Free Software Foundation, Inc.
@c This is part of the GAS manual.
@c For copying conditions, see the file as.texinfo.
@page
@node HPPA Notes
@section Notes
-As a back end for @sc{gnu} @sc{cc} @code{@value{AS}} has been throughly tested and should
+As a back end for @sc{gnu} @sc{cc} @code{@value{AS}} has been thoroughly tested and should
work extremely well. We have tested it only minimally on hand written assembly
code and no one has tested it much on the assembly output from the HP
compilers.
The format of the debugging sections has changed since the original
@code{@value{AS}} port (version 1.3X) was released; therefore,
-you must rebuild all HPPA objects and libraries with the new
+you must rebuild all HPPA objects and libraries with the new
assembler so that you can debug the final executable.
The HPPA @code{@value{AS}} port generates a small subset of the relocations
available in the SOM and ELF object file formats. Additional relocation
-support will be added as it becomes necessary.
+support will be added as it becomes necessary.
@node HPPA Options
@section Options
@example
.endm .liston
.enter .locct
-.leave .macro
+.leave .macro
.listoff
@end example
@itemx .blockz @var{n}
Reserve @var{n} bytes of storage, and initialize them to zero.
-@item .call
+@item .call
Mark the beginning of a procedure call. Only the special case with @emph{no
arguments} is allowed.
Not yet supported; the assembler rejects programs containing this directive.
@item .origin @var{lc}
-Advance location counter to @var{lc}. Synonym for the @code{@value{as}}
+Advance location counter to @var{lc}. Synonym for the @code{@value{AS}}
portable directive @code{.org}.
@item .param @var{name} [ ,@var{typ} ] [ ,@var{param}=@var{r} ]
-@c Not in HP manual; GNU HPPA extension
+@c Not in HP manual; @sc{gnu} HPPA extension
Similar to @code{.export}, but used for static procedures.
@item .proc
the section named @var{secnam}. (You can define the section number with the
HPPA @code{.space} directive.)
-@item .string "@var{str}"
@cindex @code{string} directive on HPPA
+@item .string "@var{str}"
Copy the characters in the string @var{str} to the object file.
@xref{Strings,,Strings}, for information on escape sequences you can use in
@code{@value{AS}} strings.
file.
@item .subspa @var{name} [ ,@var{params} ]
-@item .nsubspa @var{name} [ ,@var{params} ]
+@itemx .nsubspa @var{name} [ ,@var{params} ]
Similar to @code{.space}, but selects a subsection @var{name} within the
current section. You may only specify @var{params} when you create a
subsection (in the first instance of @code{.subspa} for this @var{name}).
beginning of this subsection; a power of two), @samp{access=@var{expr}} (value
for ``access rights'' field), @samp{sort=@var{expr}} (sorting order for this
subspace in link), @samp{code_only} (subsection contains only code),
-@samp{unloadable} (subsection cannot be loaded into memory), @samp{common}
-(subsection is common block), @samp{dup_comm} (initialized data may have
-duplicate names), or @samp{zero} (subsection is all zeros, do not write in
-object file).
+@samp{unloadable} (subsection cannot be loaded into memory), @samp{comdat}
+(subsection is comdat), @samp{common} (subsection is common block),
+@samp{dup_comm} (subsection may have duplicate names), or @samp{zero}
+(subsection is all zeros, do not write in object file).
@code{.nsubspa} always creates a new subspace with the given name, even
if one with the same name already exists.
+@samp{comdat}, @samp{common} and @samp{dup_comm} can be used to implement
+various flavors of one-only support when using the SOM linker. The SOM
+linker only supports specific combinations of these flags. The details
+are not documented. A brief description is provided here.
+
+@samp{comdat} provides a form of linkonce support. It is useful for
+both code and data subspaces. A @samp{comdat} subspace has a key symbol
+marked by the @samp{is_comdat} flag or @samp{ST_COMDAT}. Only the first
+subspace for any given key is selected. The key symbol becomes universal
+in shared links. This is similar to the behavior of @samp{secondary_def}
+symbols.
+
+@samp{common} provides Fortran named common support. It is only useful
+for data subspaces. Symbols with the flag @samp{is_common} retain this
+flag in shared links. Referencing a @samp{is_common} symbol in a shared
+library from outside the library doesn't work. Thus, @samp{is_common}
+symbols must be output whenever they are needed.
+
+@samp{common} and @samp{dup_comm} together provide Cobol common support.
+The subspaces in this case must all be the same length. Otherwise, this
+support is similar to the Fortran common support.
+
+@samp{dup_comm} by itself provides a type of one-only support for code.
+Only the first @samp{dup_comm} subspace is selected. There is a rather
+complex algorithm to compare subspaces. Code symbols marked with the
+@samp{dup_common} flag are hidden. This support was intended for "C++
+duplicate inlines".
+
+A simplified technique is used to mark the flags of symbols based on
+the flags of their subspace. A symbol with the scope SS_UNIVERSAL and
+type ST_ENTRY, ST_CODE or ST_DATA is marked with the corresponding
+settings of @samp{comdat}, @samp{common} and @samp{dup_comm} from the
+subspace, respectively. This avoids having to introduce additional
+directives to mark these symbols. The HP assembler sets @samp{is_common}
+from @samp{common}. However, it doesn't set the @samp{dup_common} from
+@samp{dup_comm}. It doesn't have @samp{comdat} support.
+
@item .version "@var{str}"
Write @var{str} as version identifier in object code.
@end table
@node HPPA Opcodes
@section Opcodes
For detailed information on the HPPA machine instruction set, see
-@cite{PA-RISC Architecture and Instruction Set Reference Manual}
+@cite{PA-RISC Architecture and Instruction Set Reference Manual}
(HP 09740-90039).
projects / deliverable / binutils-gdb.git / blobdiff