On 11/06/2015 08:04 PM, Steve Ellcey wrote:
When I made this change I had one regression in the GCC testsuite
(gcc.dg/fixed-point/convert-sat.c). I tracked this down to the
fact that emit_library_call_value_1 does not do any argument promotion
because it does not have the original tree type information for library
calls. It only knows about modes. I can't change emit_library_call_value_1
to do the promotion because it does not know whether to do a signed or
unsigned promotion, but expand_fixed_convert could do the conversion
before calling emit_library_call_value_1 and that is what this patch does.
Hmm, difficult. I can see how there would be a problem, but considering
how many calls to emit_library_call_* we have, I'm slightly worried
whether this is really is a good approach.
On the other hand, there seems to be precedent in this file:
if (GET_MODE_PRECISION (GET_MODE (from)) < GET_MODE_PRECISION
(SImode))
from = convert_to_mode (SImode, from, unsignedp);
The 'real' long term fix for this problem is to have tree types for builtin
functions so the proper promotions can always be done but that is a fairly
large change that I am not willing to tackle right now and it could probably
not be done in time for GCC 6.0 anyway.
Yeah, but I agree that this is the real fix. We should aim to get rid of
the emit_library_call functions.
+ if (SCALAR_INT_MODE_P (from_mode))
+ {
+ /* If we need to promote the integer function argument we need to do
Extra space at the start of the comment.
+ it here instead of inside emit_library_call_value because here we
+ know if we should be doing a signed or unsigned promotion. */
+
+ machine_mode arg_mode;
+ int unsigned_p = 0;
+
+ arg_mode = promote_function_mode (NULL_TREE, from_mode,
+ &unsigned_p, NULL_TREE, 0);
+ if (arg_mode != from_mode)
+ {
+ from = convert_to_mode (arg_mode, from, uintp);
+ from_mode = arg_mode;
+ }
+ }
Move this into a separate function (prepare_libcall_arg)? I'll think
about it over the weekend and let others chime in if they want, but I
think I'll probably end up approving it with that change.
Bernd
