[Bug target/47812] [x32] __builtin_strlen is miscompiled at -O2

[xinliangli at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47812

--- Comment #2 from davidxl <xinliangli at gmail dot com> 2011-02-19 07:44:03 
UTC ---
In ix86_expand_strlen:

if (GET_MODE (out) != Pmode)
   out = convert_to_mode (Pmode, out, 1);


Here out is REG:SI 59 -- the result register for strlen. After conversion, new
reg:DI 64 is created. There are two problems here:

1) the result is now 64, but the caller 'expand_builtin_strlen' still uses reg
59
2) the conversion itself generates an uninitialized use.

David