PR tree-optimization/79095
* tree-vrp.c (extract_range_from_binary_expr_1): For EXACT_DIV_EXPR,
if the numerator has the range ~[0,0] make the resultant range ~[0,0].
(extract_range_from_binary_expr): For MINUS_EXPR with no derived range,
if the operands are known to be not equal, then the resulting range
is ~[0,0].
(intersect_ranges): If the new range is ~[0,0] and the old range is
wide, then prefer ~[0,0].
* tree-vrp.c (overflow_comparison_p_1): New function.
(overflow_comparison_p): New function.
* tree-vrp.c (register_edge_assert_for_2): Register additional asserts
if NAME is used in an overflow test.
(vrp_evaluate_conditional_warnv_with_ops): If the ops represent an
overflow check that can be expressed as an equality test, then adjust
ops to be that equality test.
PR tree-optimization/79095
* g++.dg/pr79095-1.C: New test
* g++.dg/pr79095-2.C: New test
* g++.dg/pr79095-3.C: New test
* g++.dg/pr79095-4.C: New test
* g++.dg/pr79095-5.C: New test
* gcc.c-torture/execute/arith-1.c: Update with more cases.
* gcc.dg/tree-ssa/pr79095-1.c: New test.
From-SVN: r245434
