| Message ID | 55851248.3010408@linaro.org |
|---|---|
| State | New |
| Headers | show |
On Sat, Jun 20, 2015 at 9:12 AM, Kugan <kugan.vivekanandarajah@linaro.org> wrote: > As discussed in PR64130, this patch improves the VRP value ranges for > unsigned division. > > Bootstrapped and regression tested on x86_64-linux-gnu and regression > tested on arm-none-linux-gnu with no new regression. > > Is this OK for trunk? Hum, the patch is at least incomplete not covering the cmp == -1 case in the max value computation, no? Also I wonder if we have two VR_RANGEs as you require the code using extract_range_from_multiplicative_op_1 isn't better suited and already handles the case properly? Richard. > Thanks, > Kugan > > gcc/ChangeLog: > > 2015-06-20 Kugan Vivekanandarajah <kuganv@linaro.org> > > PR middle-end/64130 > * tree-vrp.c (extract_range_from_binary_expr_1): For unsigned > division, compute minimum when value ranges for dividend and > divisor are available. > > > gcc/testsuite/ChangeLog: > > 2015-06-20 Kugan Vivekanandarajah <kuganv@linaro.org> > > PR middle-end/64130 > * gcc.dg/tree-ssa/pr64130.c: New test.
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr64130.c b/gcc/testsuite/gcc.dg/tree-ssa/pr64130.c index e69de29..9e96abb 100644 --- a/gcc/testsuite/gcc.dg/tree-ssa/pr64130.c +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr64130.c @@ -0,0 +1,11 @@ + +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-vrp1" } */ + +int funsigned(unsigned a) +{ + return 0x1ffffffffL / a == 0; +} + +/* { dg-final { scan-tree-dump ": \\\[2, 8589934591\\\]" "vrp1" } } */ + diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c index b517363..2e1c84b 100644 --- a/gcc/tree-vrp.c +++ b/gcc/tree-vrp.c @@ -3158,7 +3158,16 @@ extract_range_from_binary_expr_1 (value_range_t *vr, type = VR_VARYING; cmp = compare_values (vr0.min, zero); if (cmp == 1) - min = zero; + { + /* For unsigned division when value ranges for dividend + and divisor are available. */ + if (vr1.type == VR_RANGE + && !symbolic_range_p (&vr0) + && !symbolic_range_p (&vr1)) + min = int_const_binop (code, vr0.min, vr1.max); + else + min = zero; + } else if (cmp == 0 || cmp == -1) min = vr0.min; else