Hi Sandra,
On 18/08/16 07:00, Sandra Loosemore wrote:
On 08/11/2016 04:31 AM, Thomas Preudhomme wrote:
diff --git a/gcc/doc/fragments.texi b/gcc/doc/fragments.texi
index
b6d8541c8ca820fa732363a05221e2cd4d1251c2..abf4e128671bb4751d21f24bb69625593d3c839e
100644
--- a/gcc/doc/fragments.texi
+++ b/gcc/doc/fragments.texi
@@ -117,12 +117,15 @@ specified, there are combinations that should not be
built. In that
case, set @code{MULTILIB_EXCEPTIONS} to be all of the switch exceptions
in shell case syntax that should not be built.
-For example the ARM processor cannot execute both hardware floating
-point instructions and the reduced size THUMB instructions at the same
-time, so there is no need to build libraries with both of these
-options enabled. Therefore @code{MULTILIB_EXCEPTIONS} is set to:
+For example on ARM targets @option{-mfloat-abi=soft} requests to use a
+softfloat implementation for floating-point operations. Therefore, it
+does not make sense to find both @option{-mfloat-abi=soft} and an
+@option{mfpu} option on the command line so @code{MULTILIB_EXCEPTIONS}
+could contain the following exception (assuming that
+@option{-mfloat-abi} comes after in @code{MULTILIB_OPTIONS} and given
+that @option{-mfloat-abi=soft} is the default value):
@smallexample
-*mthumb/*mhard-float*
+*mfpu=*
@end smallexample
@findex MULTILIB_REQUIRED
This version still has a lot of copy-editing issues. I suggest rewriting as:
For example, on ARM targets @option{-mfloat-abi=soft} requests use of
software floating-point operations, so it
does not make sense to build libraries with both
@option{-mfloat-abi=soft} and an @option{-mfpu} option.
@code{MULTILIB_EXCEPTIONS} could contain the following exception
Thanks for the help. That sounds better indeed. Future readers thank you ;-)
but here I get stuck in suggesting a rewrite, because I can't parse this part at
all to figure out what you're trying to say:
(assuming that
@option{-mfloat-abi} comes after in @code{MULTILIB_OPTIONS} and given
that @option{-mfloat-abi=soft} is the default value):
"comes after in"? Comes after what? If the order is important here, the
documentation should explain why instead of just "assuming" things about it.
Actually I made a mistake in that example. What I meant is that a wildchar also
match slashes so one must consider the order of options in MULTILIB_OPTIONS when
understanding what option sets will a MULTILIB_EXCEPTION rule match.
Thinking about this, MULTILIB_EXCEPTIONS and MULTILIB_REQUIRED don't specify the
syntax of the directives (option separated by slashes) and the important of the
order of operations in MULTILIB_OPTIONS. The documentation for MULTILIB_REUSE is
a better example for that.
I think that Richard makes a good case for going away altogher from ARM as an
example to both keep things simple and be more future proof. I'll rewrite that
patch to do this and specify the syntax of MULTILIB_EXCEPTIONS and
MULTILIB_REQUIRED. Do you prefer these two aspects to be in 2 different patches?
-Sandra the confused
My mistake really.
Best regards,
Thomas
