-@c Copyright (C) 1991, 1992, 1993, 1994, 1995 Free Software Foundation, Inc.
+@c Copyright (C) 1991-2015 Free Software Foundation, Inc.
@c This is part of the GAS manual.
@c For copying conditions, see the file as.texinfo.
@page
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} ]
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