Is vec_init<mode> allowed to FAIL?

[Jim Wilson]

Jan Hoogerbrugge wrote:
> I see however that no code is generated if trimedia_expand_vector_init()
> returns 0 and the define_expand FAILs. I also see in other targets that a
> vec_init always ends with a DONE. Could it be that vec_init is not allowed to
> FAIL?

Grep for "vec_init", and we see that it is used in expr.c, 
store_constructor(), case VECTOR_TYPE.  It calls optab_handler to set 
icode, and then at the end calls GEN_FCN (icode).  There is no provision 
for the GEN_FCN (icode) call returning failure, so yes, vec_init is not 
allowed to fail.

This could probably be fixed with a little code rearrangement.  For 
instance, you could try putting all code starting with the line that 
tests "need_to_clear && size > 0 && !vector" into a loop that iterates 
twice.  If vector is not set, then we exit the loop after emitting code. 
  If vector is set, and the GEN_FCN call succeeded, then we exit the 
loop.  If vector is set, and the GEN_FCN call fails, then we clear 
vector, throw away any RTL that may have been emitted, and loop back for 
a second pass using the non-vector code, which always succeeds. 
Throwing away the temporary RTL can be accomplished by using 
start_sequence and end_sequence.  There may also be other ways to fix this.

Jim