strlen: Handle vector CONSTRUCTORs [PR117057]

The following patch handles VECTOR_TYPE_P CONSTRUCTORs in
count_nonzero_bytes, including handling them if they have some elements
non-constant.
If there are still some constant elements before it (in the range queried),
we derive info at least from those bytes and consider the rest as unknown.

The first 3 hunks just punt in IMHO problematic cases, the spaghetti code
considers byte_size 0 as unknown size, determine yourself, so if offset
is equal to exp size, there are 0 bytes to consider (so nothing useful
to determine), but using byte_size 0 would mean use any size.
Similarly, native_encode_expr uses int type for offset (and size), so
padding it offset larger than INT_MAX could be silent miscompilation.

I've guarded the test to just a couple of targets known to handle it,
because e.g. on ia32 without -msse forwprop1 seems to lower the CONSTRUCTOR
into 4 BIT_FIELD_REF stores and I haven't figured out on what exactly
that depends on (e.g. powerpc* is fine on any CPUs, even with -mno-altivec
-mno-vsx, even -m32).

2024-11-30  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/117057
	* tree-ssa-strlen.cc (strlen_pass::count_nonzero_bytes): Punt also
	when byte_size is equal to offset or nchars.  Punt if offset is bigger
	than INT_MAX.  Handle vector CONSTRUCTOR with some elements constant,
	possibly followed by non-constant.

	* gcc.dg/strlenopt-32.c: Remove xfail and vect_slp_v2qi_store_unalign
	specific scan-tree-dump-times directive.
	* gcc.dg/strlenopt-96.c: New test.

0 files changed, 0 insertions, 0 deletions