[gcc r13-5453] Clarify -shared effect on crtfastmath.o

[gcc r13-5453] Clarify -shared effect on crtfastmath.o

[Richard Biener]

https://gcc.gnu.org/g:b799acef461bcb78d77819dd27c8e4806177d841

commit r13-5453-gb799acef461bcb78d77819dd27c8e4806177d841
Author: Richard Biener <rguenther@suse.de>
Date:   Fri Jan 13 08:57:12 2023 +0100

    Clarify -shared effect on crtfastmath.o
    
    This rewords the note to not specifically mention crtfastmath.o
    but FP environment altering by -ffast-math or -Ofast.
    
            PR target/55522
            * doc/invoke.texi (-shared): Clarify effect on -ffast-math
            and -Ofast FP environment side-effects.

Diff:
---
 gcc/doc/invoke.texi | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 06d77983e30..a371cd91ef8 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -17696,8 +17696,9 @@ needs to build supplementary stub code for constructors to work.  On
 multi-libbed systems, @samp{gcc -shared} must select the correct support
 libraries to link against.  Failing to supply the correct flags may lead
 to subtle defects.  Supplying them in cases where they are not necessary
-is innocuous. For x86, crtfastmath.o will not be added when
-@option{-shared} is specified. }
+is innocuous.  @option{-shared} suppresses the addition of startup code
+to alter the floating-point environment as done with @option{-ffast-math},
+@option{-Ofast} or @option{-funsafe-math-optimizations} on some targets.}
 
 @item -shared-libgcc
 @itemx -static-libgcc