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Make it easier to use shared libraries on x86 with
`mmc --make'.
There is now a third kind of object file, `.lpic_o'.
These files are compiled with `--pic-reg' but not with
CFLAGS_FOR_PIC, so they can be linked with shared Mercury
libraries.
On x86, executables which are linked with shared Mercury
libraries now depend on $(main_module.lpic_os), not
$(main_module.os).
This doesn't work with Mmake because ml doesn't know
which libraries are Mercury libraries, so it can't
link with the static versions of those libraries if
MERCURY_LINKAGE is set to "static".
configure.in:
bindist/bindist.configure.in:
bindist/bindist.build_vars.in:
Work out whether `.lpic_o' files are needed.
compiler/modules.m:
Add `.lpic_o' to the list of grade or architecture
dependent files.
NEWS:
README.Linux:
compiler/options.m:
doc/user_guide.texi:
Document MERCURY_LINKAGE, LINKAGE, --linkage,
--mercury-linkage and -R.
compiler/options_file.m:
compiler/make.program_target.m:
Handle LINKAGE and MERCURY_LINKAGE variables.
Allow LIBGRADES, LINKAGE and MERCURY_LINKAGE to be target-specific.
scripts/mmc.in:
Set up the default linkage using the MERCURY_LINKAGE
variable.
compiler/compile_target_code.m:
Build `.lpic_o' files.
Work out which type of object files to link with.
When linking statically with Mercury libraries,
find the absolute pathname for the `.a' file
for each Mercury library, and pass that to ml,
rather than just using `-lname'.
Pass `-R' options to ml for each `-R' option to mmc.
compiler/make.module_target.m:
compiler/make.program_target.m:
compiler/mercury_compile.m:
Specify which type of object files to build.
compiler/make.program_target.m:
compiler/make.module_target.m:
Make sure all generated object files are cleaned up.
compiler/prog_io.m:
Add a better message for files which can't be found.
compiler/make.util.m:
Add `.lpic_o' to the list of extensions.
compiler/Mmakefile:
profiler/Mmakefile:
deep_profiler/Mmakefile:
Pass `--linkage shared' to mmc (`--shared' is in MLFLAGS).
tests/Mmakefile:
tests/mmc_make/Mmakefile:
tests/mmc_make/Mercury.options:
tests/mmc_make/complex_test.{m,exp}:
tests/mmc_make/hello.{m,exp}:
Test `mmc --make'.
tests/lib/complex*.m:
The complex numbers library from the extras distribution,
for use in the mmc_make tests.
47 lines
2.5 KiB
Plaintext
47 lines
2.5 KiB
Plaintext
This file documents just the Linux/x86 port.
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For the Linux/PowerPC port, see README.Linux-PPC.
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For the Linux/Alpha port, see README.Linux-Alpha.
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(Ports to Linux on other architectures have not yet
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been attempted, but should not be difficult.)
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On Linux with a.out, shared libraries are not supported.
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If you still have an old a.out system, the auto-configuration might
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wrongly assume your Linux system uses ELF; if that happens, you will you
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have to manually edit the EXT_FOR_SHARED_LIB variable in Mmake.common.
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On Linux with ELF, shared libraries are supported. However, ELF shared
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libraries require position-independent code, and (partly due to
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limitations in our current compilation technology, but partly due to
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limitations in the x86 architecture) this is quite costly for Mercury --
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probably considerably more costly than it is for C.
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Nevertheless, since shared libraries reduces disk usage, improve link
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times, and allow run-time sharing of the Mercury libraries between
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different applications, using them is a good idea.
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Currently the default is that programs do *not* use the Mercury shared
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libraries. (Probably it ought to be the other way around, but that
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happened to be a little bit harder to implement. We may change this in
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a future release.)
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To use the shared libraries, you must compile your program with
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`mmc --pic-reg' and link with `ml --shared' or add
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`MGNUCFLAGS=--pic-reg' and `MLFLAGS=--shared' to your Mmake file.
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If you are using `mmc --make' you can set the MERCURY_LINKAGE Mmake
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variable to "shared" in the Mercury.options file or the environment,
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or use `mmc --make --linkage shared'.
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Mercury code compiled with `--pic-reg' or with gcc's `-fpic' option has
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what we shall call "PIC linkage", whereas Mercury code compiled without
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these options has "non-PIC linkage". The static version of the Mercury
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libraries has non-PIC linkage, while the shared version has PIC linkage.
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Be careful that you do not try to link Mercury code with PIC linkage and
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Mercury code with non-PIC linkage into the same executable, otherwise you
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will probably get an obscure link error about `MR_grade_...' undefined
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or `MR_runtime_grade' multiply defined.
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(The reason for this is that standard non-PIC Mercury code uses the
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`ebx' register in ways that are incompatible with its uses as the global
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offset table pointer register in PIC code. If only the Intel
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architecture wasn't so register-starved, we wouldn't need to use `ebx',
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and then PIC and non-PIC code could be mixed without any problems.)
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