middle-end: fix 0 offset creation and folding [PR115936]

As shown in PR115936 SCEV and IVOPTS create an invalidate IV when the IV is
a pointer type:

ivtmp.39_65 = ivtmp.39_59 + 0B;

where the IVs are DI mode and the offset is a pointer.
This comes from this weird candidate:

Candidate 8:
  Var befor: ivtmp.39_59
  Var after: ivtmp.39_65
  Incr POS: before exit test
  IV struct:
    Type:       sizetype
    Base:       0
    Step:       0B
    Biv:        N
    Overflowness wrto loop niter:       No-overflow

This IV was always created just ended up not being used.

This is created by SCEV.

simple_iv_with_niters in the case where no CHREC is found creates an IV with
base == ev, offset == 0;

however in this case EV is a POINTER_PLUS_EXPR and so the type is a pointer.
it ends up creating an unusable expression.

gcc/ChangeLog:

	PR tree-optimization/115936
	* tree-scalar-evolution.cc (simple_iv_with_niters): Use sizetype for
	pointers.

0 files changed, 0 insertions, 0 deletions