This patch eliminates the gen-py-const.awk variant of gen-as-const,
switching to use of gnu-as-const.py (with a new --python option) to
process .pysym files (i.e., to generate nptl_lock_constants.py), as
the syntax of those files is identical to that of .sym files.
Note that the generated nptl_lock_constants.py is *not* identical to
the version generated by the awk script. Apart from the trivial
changes (comment referencing the new script, and output being sorted),
the constant FUTEX_WAITERS, PTHREAD_MUTEXATTR_FLAG_BITS,
PTHREAD_MUTEXATTR_FLAG_PSHARED and PTHREAD_MUTEX_PRIO_CEILING_MASK are
now output as positive rather than negative constants (on x86_64
anyway; maybe not necessarily on 32-bit systems):
< FUTEX_WAITERS = -2147483648
---
> FUTEX_WAITERS = 2147483648
< PTHREAD_MUTEXATTR_FLAG_BITS = -251662336
< PTHREAD_MUTEXATTR_FLAG_PSHARED = -2147483648
---
> PTHREAD_MUTEXATTR_FLAG_BITS = 4043304960
> PTHREAD_MUTEXATTR_FLAG_PSHARED = 2147483648
< PTHREAD_MUTEX_PRIO_CEILING_MASK = -524288
---
> PTHREAD_MUTEX_PRIO_CEILING_MASK = 4294443008
This is because gen-as-const has a cast of the constant value to long
int, which gen-py-const lacks.
I think the positive values are more logically correct, since the
constants in question are in fact unsigned in C. But to reliably
produce gen-as-const.py output for constants that always (in C and
Python) reflects the signedness of values with the high bit of "long
int" set would mean more complicated logic needs to be used in
computing values.
The more correct positive values by themselves produce a failure of
nptl/test-mutexattr-printers, because masking with
~PTHREAD_MUTEXATTR_FLAG_BITS & ~PTHREAD_MUTEX_NO_ELISION_NP now leaves
a bit -1 << 32 in the Python value, resulting in a KeyError exception.
To avoid that, places masking with ~ of one of the constants in
question are changed to mask with 0xffffffff as well (this reflects
how ~ in Python applies to an infinite-precision integer whereas ~ in
C does not do any promotions beyond the width of int).
Tested for x86_64.
* scripts/gen-as-const.py (main): Handle --python option.
* scripts/gen-py-const.awk: Remove.
* Makerules (py-const-script): Use gen-as-const.py.
($(py-const)): Likewise.
* nptl/nptl-printers.py (MutexPrinter.read_status_no_robust): Mask
with 0xffffffff together with ~(PTHREAD_MUTEX_PRIO_CEILING_MASK).
(MutexAttributesPrinter.read_values): Mask with 0xffffffff
together with ~PTHREAD_MUTEXATTR_FLAG_BITS and
~PTHREAD_MUTEX_NO_ELISION_NP.
* manual/README.pretty-printers: Update reference to
gen-py-const.awk.
This patch converts the tst-signal-numbers test from shell + awk to
Python.
As with gen-as-const, the point is not so much that shell and awk are
problematic for this code, as that it's useful to build up general
infrastructure in Python for use of a range of code involving
extracting values from C headers. This patch moves some code from
gen-as-const.py to a new glibcextract.py, which also gains functions
relating to listing macros, and comparing the values of a set of
macros from compiling two different pieces of code.
It's not just signal numbers that should have such tests; pretty much
any case where glibc copies constants from Linux kernel headers should
have such tests that the values and sets of constants agree except
where differences are known to be OK. Much the same also applies to
structure layouts (although testing those without hardcoding lists of
fields to test will be more complicated).
Given this patch, another test for a set of macros would essentially
be just a call to glibcextract.compare_macro_consts (plus boilerplate
code - and we could move to having separate text files defining such
tests, like the .sym inputs to gen-as-const, so that only a single
Python script is needed for most such tests). Some such tests would
of course need new features, e.g. where the set of macros changes in
new kernel versions (so you need to allow new macro names on the
kernel side if the kernel headers are newer than the version known to
glibc, and extra macros on the glibc side if the kernel headers are
older). tst-syscall-list.sh could become a Python script that uses
common code to generate lists of macros but does other things with its
own custom logic.
There are a few differences from the existing shell + awk test.
Because the new test evaluates constants using the compiler, no
special handling is needed any more for one signal name being defined
to another. Because asm/signal.h now needs to pass through the
compiler, not just the preprocessor, stddef.h is included as well
(given the asm/signal.h issue that it requires an externally provided
definition of size_t). The previous code defined __ASSEMBLER__ with
asm/signal.h; this is removed (__ASSEMBLY__, a different macro,
eliminates the requirement for stddef.h on some but not all
architectures).
Tested for x86_64, and with build-many-glibcs.py.
* scripts/glibcextract.py: New file.
* scripts/gen-as-const.py: Do not import os.path, re, subprocess
or tempfile. Import glibcexctract.
(compute_c_consts): Remove. Moved to glibcextract.py.
(gen_test): Update reference to compute_c_consts.
(main): Likewise.
* sysdeps/unix/sysv/linux/tst-signal-numbers.py: New file.
* sysdeps/unix/sysv/linux/tst-signal-numbers.sh: Remove.
* sysdeps/unix/sysv/linux/Makefile
($(objpfx)tst-signal-numbers.out): Use tst-signal-numbers.py.
Redirect stderr as well as stdout.
It was reported in
<https://sourceware.org/ml/libc-alpha/2018-12/msg00045.html> that
gen-as-const.py fails to generate test code in the case where a .sym
file has no symbols in it, so resulting in a test failing to link for
Hurd.
The relevant difference from the old awk script is that the old script
treated '--' lines as indicating that the text to do at the start of
the test (or file used to compute constants) should be output at that
point if not already output, as well as treating lines with actual
entries for constants like that. This patch changes gen-as-const.py
accordingly, making it the sole responsibility of the code parsing
.sym files to determine when such text should be output and ensuring
it's always output at some point even if there are no symbols and no
'--' lines, since not outputting it means the test fails to link.
Handling '--' like that also avoids any problems that would arise if
the first entry for a symbol were inside #ifdef (since the text in
question must not be output inside #ifdef).
Tested for x86_64, and with build-many-glibcs.py for i686-gnu. Note
that there are still compilation test failures for i686-gnu
(linknamespace tests, possibly arising from recent posix_spawn-related
changes).
* scripts/gen-as-const.py (compute_c_consts): Take an argument
'START' to indicate that start text should be output.
(gen_test): Likewise.
(main): Generate 'START' for first symbol or '--' line, or at end
of input if not previously generated.
hurd's jmp_buf-ssp.sym does not define any symbol.
scripts/gen-as-const.py currently was emitting an empty line in that
case, and the gawk invocation was prepending "asconst_" to it, ending up
with:
.../build/glibc/setjmp/test-as-const-jmp_buf-ssp.c:1:2: error: expected « = », « , », « ; », « asm » or
« __attribute__ » at end of input
1 | asconst_
| ^~~~~~~~
* scripts/gen-as-const.py (main): Avoid emitting empty line when
there is no element in `consts'.
This patch replaces gen-as-const.awk, and some fragments of the
Makefile code that used it, by a Python script. The point is not such
much that awk is problematic for this particular script, as that I'd
like to build up a general Python infrastructure for extracting
information from C headers, for use in writing tests of such headers.
Thus, although this patch does not set up such infrastructure, the
compute_c_consts function in gen-as-const.py might be moved to a
separate Python module in a subsequent patch as a starting point for
such infrastructure.
The general idea of the code is the same as in the awk version, but no
attempt is made to make the output files textually identical. When
generating a header, a dict of constant names and values is generated
internally then defines are printed in sorted order (rather than the
order in the .sym file, which would have been used before). When
generating a test that the values computed match those from a normal
header inclusion, the test code is made into a compilation test using
_Static_assert, where previously the comparisons were done only when
the test was executed. One fragment of test generation (converting
the previously generated header to use asconst_* prefixes on its macro
names) is still in awk code in the makefiles; only the .sym processing
and subsequent execution of the compiler to extract constants have
moved to the Python script.
Tested for x86_64, and with build-many-glibcs.py.
* scripts/gen-as-const.py: New file.
* scripts/gen-as-const.awk: Remove.
* Makerules ($(common-objpfx)%.h $(common-objpfx)%.h.d): Use
gen-as-const.py.
($(objpfx)test-as-const-%.c): Likewise.
Joseph Myers
Samuel Thibault