| Message ID | d5cea256-62d2-3576-480e-6902e378861a@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | VRP: normalize VR_VARYING in PLUS/MINUS_EXPR handling | expand |
On Tue, Sep 11, 2018 at 12:34 PM Aldy Hernandez <aldyh@redhat.com> wrote: > > For addition and subtraction, we're currently punting on things like > [0,0] - VR_VARYING. However, if we normalize VR_VARYING to the entire > domain, we can see that the above is actually [-MIN+1, +MAX]. > > We would've normally caught this sort of things with my rewrite of the > binary operators, but PLUS/MINUS are special in that they're pretty much > the only operator that keeps symbolics through it's calculations. This > is why we can't just blindly treat symbolics as [-MIN, +MAX] as I've > done elsewhere. PLUS/MINUS are handled specially (ugly) :-/. > > OK for trunk? OK. >
gcc/ * tree-vrp.c (extract_range_from_binary_expr_1): Normalize VR_VARYING for PLUS/MINUS_EXPR. diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c index 8f16713300c..27ef96c27e7 100644 --- a/gcc/tree-vrp.c +++ b/gcc/tree-vrp.c @@ -1426,6 +1426,22 @@ extract_range_from_binary_expr_1 (value_range *vr, range and see what we end up with. */ if (code == PLUS_EXPR || code == MINUS_EXPR) { + /* This will normalize things such that calculating + [0,0] - VR_VARYING is not dropped to varying, but is + calculated as [MIN+1, MAX]. */ + if (vr0.type == VR_VARYING) + { + vr0.type = VR_RANGE; + vr0.min = vrp_val_min (expr_type); + vr0.max = vrp_val_max (expr_type); + } + if (vr1.type == VR_VARYING) + { + vr1.type = VR_RANGE; + vr1.min = vrp_val_min (expr_type); + vr1.max = vrp_val_max (expr_type); + } + const bool minus_p = (code == MINUS_EXPR); tree min_op0 = vr0.min; tree min_op1 = minus_p ? vr1.max : vr1.min;