On 07/01/2024 19:32, Segher Boessenkool wrote:
On Sun, Jan 07, 2024 at 06:04:23PM +0800, LIU Hao wrote:
在 2024/1/6 2:46, Segher Boessenkool 写道:
The C constraint means "Any operand whatsoever is allowed." Here you
are saying to use it both as input and as output, and GCC does not know
how to reload wherever it chose to put it.
Would you mind elaborating a bit more? On x86 and x86-64 it's almost always
the case that an expression can be used as either a source or a destination.
This is just GCC internals. The compiler will never look at the
template string in an asm at all, anyway.
I don't know why exactly you get the error. Make a compilable
reproducer, file a bug (<https://gcc.gnu.org/bugs.html>), it sounds like
something we can improve :-)
I've filed it :
<https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113280>
I don't know if this is something that the developer will want to spend
much time on, but it might appeal to someone's curiosity!
David
