tree-ssa-math-opts: Fix up uaddc/usubc pattern matching [PR110271]

The following testcase ICEs, because I misremembered what the return value
from match_arith_overflow is.  It isn't true if __builtin_*_overflow was
matched, but it is true only in the BIT_NOT_EXPR case if stmt was removed.

So, if match_arith_overflow matches something, gsi_stmt (gsi) will not
be stmt and match_uaddc_usubc will be confused and can ICE.

The following patch fixes it by checking if gsi_stmt (gsi) == stmt,
in that case we know it is still a PLUS_EXPR/MINUS_EXPR and we can try to
pattern match it further as UADDC/USUBC.

2023-06-16  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/110271
	* tree-ssa-math-opts.cc (math_opts_dom_walker::after_dom_children)
	<case PLUS_EXPR>: Ignore return value from match_arith_overflow,
	instead call match_uaddc_usubc only if gsi_stmt (gsi) is still stmt.

	* gcc.c-torture/compile/pr110271.c: New test.

0 files changed, 0 insertions, 0 deletions