From: Christophe Lyon <christophe.lyon@linaro.org>
To: Joseph Myers <joseph@codesourcery.com>
Cc: "gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>
Subject: Re: Fix genmultilib reuse rule checks for large sets of option combinations
Date: Wed, 28 Jun 2017 08:04:00 -0000 [thread overview]
Message-ID: <CAKdteOZmBMtic-U7667DS2+Es_cT0X6mc3QWMWNHP5zH0pjznA@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1706082027370.28164@digraph.polyomino.org.uk>
Hi Joseph,
On 8 June 2017 at 22:28, Joseph Myers <joseph@codesourcery.com> wrote:
> genmultilib computes combination_space, a list of all combinations of
> options in MULTILIB_OPTIONS that might have multilibs built for them
> (some of which may end up not having multilibs built for them, and
> some of those may end up being mapped to other multilibs with
> MULTILIB_REUSE). It is then used to validate the right hand part of
> MULTILIB_REUSE rules, checking with expr that combination_space
> matches a basic regular expression derived from that right hand part.
>
> There are two problems with this approach to validation:
>
> * It requires that right hand part to have options in the same order
> as in MULTILIB_OPTIONS, in contradiction to the documentation of
> MULTILIB_REUSE saying that order does not matter there.
>
> * combination_space can be so large that the expr call fails with an
> E2BIG error. I have a local ARM configuration with 40 multilibs but
> 3840 combinations of options from MULTILIB_OPTIONS (so 3839 listed
> in combination_space, since it doesn't list the default multilib)
> and 996 MULTILIB_REUSE rules. This generates a combination_space
> string longer than the Linux kernel's MAX_ARG_STRLEN (PAGE_SIZE *
> 32, the limit on the length of a single argv string), so that expr
> cannot be run.
>
> This patch changes the validation approach to generate a much shorter
> extended regular expression for any sequence of multilib options in
> any order, and uses that for the validation instead.
>
> Tested with a built for arm-none-eabi --with-multilib-list=aprofile
> (as a configuration that uses MULTILIB_REUSE).
>
> 2017-06-08 Joseph Myers <joseph@codesourcery.com>
>
> * genmultilib (combination_space): Remove variable.
> Validate reuse rules against regular expression for any sequence
> of multilib options in any order.
>
> Index: gcc/genmultilib
> ===================================================================
> --- gcc/genmultilib (revision 249028)
> +++ gcc/genmultilib (working copy)
> @@ -186,8 +186,7 @@
> EOF
> chmod +x tmpmultilib
>
> -combination_space=`initial=/ ./tmpmultilib ${options}`
> -combinations="$combination_space"
> +combinations=`initial=/ ./tmpmultilib ${options}`
>
> # If there exceptions, weed them out now
> if [ -n "${exceptions}" ]; then
> @@ -460,6 +459,15 @@
> echo "NULL"
> echo "};"
>
> +# Generate a regular expression to validate option combinations.
> +options_re=
> +for set in ${options}; do
> + for opt in `echo ${set} | sed -e 's_[/|]_ _g'`; do
> + options_re="${options_re}${options_re:+|}${opt}"
> + done
> +done
> +options_re="^/((${options_re})/)*\$"
> +
> # Output rules used for multilib reuse.
> echo ""
> echo "static const char *const multilib_reuse_raw[] = {"
> @@ -473,7 +481,7 @@
> # in this variable, it means no multilib will be built for current reuse
> # rule. Thus the reuse purpose specified by current rule is meaningless.
> if expr "${combinations} " : ".*/${combo}/.*" > /dev/null; then
> - if expr "${combination_space} " : ".*/${copts}/.*" > /dev/null; then
> + if echo "/${copts}/" | grep -E "${options_re}" > /dev/null; then
> combo="/${combo}/"
> dirout=`./tmpmultilib3 "${combo}" "${todirnames}" "${toosdirnames}" "${enable_multilib}"`
> copts="/${copts}/"
>
This broke my builds, where I do not use
--with-multilib-list=aprofile, and uses the default.
I suspect it would also fail for the aprofile multilibs, though.
I think there's a problem with options that have a '+' which confuses
the regexp in options_re.
For instance, I get this error message:
The rule mthumb=mthumb/mfpu.auto/march.armv5te+fp contains an option
absent from MULTILIB_OPTIONS.
A bit of manual debugging led me to:
$ echo /mthumb/mfpu=auto/march=armv5te+fp/ | grep -E
'^/((marm|mthumb|mfpu=auto|march=armv5te+fp|march=armv7+fp|mfloat-abi=hard)/)*$'
[empty result]
Replacing the '+' in armv5te+fp with either '\+' or '.' allows the
pattern to match:
/mthumb/mfpu=auto/march=armv5te+fp/
Is it a matter of adding sed -e 's/\+/./g' when building options_re ?
Or would this break something else?
Thanks,
Christophe
> --
> Joseph S. Myers
> joseph@codesourcery.com
next prev parent reply other threads:[~2017-06-28 8:04 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-08 20:28 Joseph Myers
2017-06-14 15:09 ` Ping " Joseph Myers
2017-06-27 15:48 ` Ping^2 " Joseph Myers
2017-06-27 16:14 ` Jeff Law
2017-06-28 8:04 ` Christophe Lyon [this message]
2017-06-28 8:09 ` Christophe Lyon
2017-06-28 8:14 ` Andreas Schwab
2017-06-28 9:17 ` Christophe Lyon
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