+++ /dev/null
--*- text -*-
-
-PORTING:
-
-Sorry, no description of the interfaces is written up yet. Look at existing
-back ends and work from there.
-
-New hosts: The configure script, which is generated by autoconf,
-should handle all host specific configuration.
-
-New target formats: Look at the BFD_ASSEMBLER code. The a.out or ELF
-code might be a fair example. There are no "good" examples yet,
-unfortunately, nor any good documentation of the changes.
-
-New target processors: Check first to see if the BFD_ASSEMBLER interface is
-supported by the file format code you need to use.
-
-DOCUMENTATION:
-
-The internals of gas need documenting.
-
-The documentation should also contain a "Trouble" section similar to gcc's
-manual: real bugs, common problems, incompatibilities, etc.
-
-Anyone want to offer to maintain a man page?
-
-BFD CONVERSION:
-
-The "#ifdef BFD_ASSEMBLER" code is on its way in; the "#ifndef BFD_ASSEMBLER"
-code is on its way out. The new code uses BFD data structures, and calls BFD
-for anything that needs to be written to the output file. The old code did all
-the writing itself, or in a couple of cases, used BFD as a slightly higher
-level than stdio (i.e., bfd_seek, bfd_write -- these are not the preferred
-interface).
-
-Because of this, some of this code is messy. Lots of ifdef's, and the
-non-BFD_ASSEMBLER version often has multiple conditional tests inside it for
-various processors or formats. As the various targets get converted over,
-these will gradually go away.
-
-TO DO:
-
-Remove DONTDEF code, commented-out code.
-
-Eliminate, as much as possible, anything not in config that is conditionalized
-on a CPU, format, or environment.
-
-Merge COFF support into one version, supporting all the pseudo-ops used in
-either versions now, but using BFD for high-level operations. (See second
-following item.) Currently there are two versions (plus the new BFD code),
-which support different features, and are used on different targets.
-
-Convert remaining a.out/b.out targets to using the BFD_ASSEMBLER code by
-default.
-
-Finish conversion to using BFD for all object file writing. (This is the
-BFD_ASSEMBLER code, not BFD or BFD_HEADERS.) VMS might be the tough one here,
-since there's no BFD support for it at all yet. Eliminate the old code. Some
-of this can be done target by target, so doing a target where the CPU or
-format already supports BFD_ASSEMBLER mode may be easiest.
-
-Fix lots of uses of empty strings to use null pointers. Will improve
-efficiency, and should make code clearer too.
-
-Clean up comments; lots of 'em are one previous maintainer griping about
-another previous maintainer, unrelated to the code. (And with no names,
-they're not so fun to read. :-)
-
-For sparc: "call 0" becomes "jmpl %g0,%l7", and similarly for absolute
-addresses in -4096...4095. (Solaris assembler does this. No
-relocation required, no absolute symbol needed.) For addresses
-outside the range, for COFF, keep generating an absolute symbol to use
-for relocs.
-
-Get Steve to document H8/500 stuff (and others).
-
-Improve test suite. Incorporate more reported net bugs, and non-confidential
-Cygnus customer bugs, and anything else.
-
-Add support for i386/i486 16-bit mode, so operating system initialization code
-doesn't require a separate assembler nor lots of `.byte' directives.
-
-See if it's more maintainable (and not too much of a performance loss) to use
-a yacc grammar for parsing input. The lexer will have to be flexible, and the
-grammar will have to contain any construct used on any platform, but it may be
-easier to maintain, instead of having code in most of the back ends.
-
-PIC support.
-
-Torbjorn Granlund <tege@cygnus.com> writes, regarding alpha .align:
-
- Please make sure the .align directive works as in digital's assembler.
- They fill the space with a sequence of "bis $31,$31,$31;ldq_u $31,0($30)"
- since these two instructions can dual-issue. Since .align is ued a lot by
- gcc, it is an important optimization.
-
-(From old "NOTES" file to-do list, not really reviewed:)
-
-fix relocation types for i860, perhaps by adding a ref pointer to fixS?
-
-remove the ifdef's from fx_callj tests?
-
-space tighten sparc alignment?
-
-md_ => tc_
-
-share b.out with a.out.
+++ /dev/null
-
- The GAS Configuration Plan
-
-Theory:
-
-The goal of the new configuration scheme is to bury all object format
-and target processor dependancies in object and target specific files.
-That is, to move all #ifdef's out of the gas common code.
-
-Here's how it works. There is a .h and a .c file for each object file
-format and a .h and a .c file for each target processor. The
-configure script creates symlinks in the current directory to the
-appropriate files in the config directory. configure also serves as a
-list of triplets {host, target, object-format} that have been tested
-at one time or another. I also recommend that configure be used to
-document triplet specific notes as to purpose of the triplet, etc.
-
-Implementation:
-
-obj-format.h is a {sym}link to .../config/obj-something.h. It is intended
-
-All gas .c files include as.h.
-
-as.h #define's "GAS", includes config.h, defines a number of gas
-specific structures and types, and then includes tc.h, obj.h, and
-targ-env.h.
-
-targ-env.h defines a target environment specific preprocessor flag,
-eg, TE_SUN, and then includes obj-format.h.
-
-obj-format.h defines an object format specific preprocessor flag, eg,
-OBJ_AOUT, OBJ_BOUT, OBJ_COFF, includes "targ-cpu.h", and then defines
-the object specific macros, functions, types, and structures.
-
-targ-cpu.h
-
-targ-cpu.c
-
-Porting:
-
-There appear to be four major types of ports; new hosts, new target
-processors, new object file formats, and new target environments.
projects / binutils-gdb.git / commitdiff