[gcc(refs/users/marxin/heads/marxin-gcc-benchmark-branch)] rs6000: Fix -mlong-double documentation

[Martin Liska]

https://gcc.gnu.org/g:9439378f7a08cf9c8f524c9f3758a37d804ac106

commit 9439378f7a08cf9c8f524c9f3758a37d804ac106
Author: Carl Love <cel@us.ibm.com>
Date:   Thu Mar 5 12:52:35 2020 -0600

    rs6000: Fix -mlong-double documentation
    
    gcc/ChangeLog
    
    2020-03-09  Carl Love  <cel@us.ibm.com>
    
            * config/rs6000/rs6000.opt: Update the description of the
            command line option.

Diff:
---
 gcc/config/rs6000/rs6000.opt | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gcc/config/rs6000/rs6000.opt b/gcc/config/rs6000/rs6000.opt
index ed3b44a04a6..f95b8279270 100644
--- a/gcc/config/rs6000/rs6000.opt
+++ b/gcc/config/rs6000/rs6000.opt
@@ -414,7 +414,8 @@ Warn about deprecated 'vector long ...' AltiVec type usage.
 
 mlong-double-
 Target RejectNegative Joined UInteger Var(rs6000_long_double_type_size) Save
--mlong-double-[64,128]	Specify size of long double.
+Use -mlong-double-64 for 64-bit IEEE floating point format.  Use
+-mlong-double-128 for 128-bit floating point format (either IEEE or IBM).
 
 ; This option existed in the past, but now is always on.
 mlra