Hello,
this patch tries to tighten a bit the range estimate for x%y. slp-perm-7.c
started failing by vectorizing more than expected, I assumed it was a good
thing and updated the test. I am less conservative than Jakub with
division by 0, but I still don't really understand how empty ranges are
supposed to be represented in VRP.
Bootstrap+testsuite on x86_64-linux-gnu.
2015-05-02 Marc Glisse <marc.gli...@inria.fr>
PR tree-optimization/64454
gcc/
* tree-vrp.c (extract_range_from_binary_expr_1) <TRUNC_MOD_EXPR>:
Rewrite.
gcc/testsuite/
* gcc.dg/tree-ssa/vrp97.c: New file.
* gcc.dg/vect/slp-perm-7.c: Update.
--
Marc GlisseIndex: gcc/testsuite/gcc.dg/tree-ssa/vrp97.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/vrp97.c (revision 0)
+++ gcc/testsuite/gcc.dg/tree-ssa/vrp97.c (working copy)
@@ -0,0 +1,13 @@
+/* PR tree-optimization/64454 */
+/* { dg-options "-O2 -fdump-tree-vrp1" } */
+
+int f(int a, int b)
+{
+ if (a < -3 || a > 13) __builtin_unreachable();
+ if (b < -6 || b > 9) __builtin_unreachable();
+ int c = a % b;
+ return c >= -3 && c <= 8;
+}
+
+/* { dg-final { scan-tree-dump "return 1;" "vrp1" } } */
+/* { dg-final { cleanup-tree-dump "vrp1" } } */
Index: gcc/testsuite/gcc.dg/vect/slp-perm-7.c
===================================================================
--- gcc/testsuite/gcc.dg/vect/slp-perm-7.c (revision 222708)
+++ gcc/testsuite/gcc.dg/vect/slp-perm-7.c (working copy)
@@ -63,15 +63,15 @@ int main (int argc, const char* argv[])
foo (input, output, input2, output2);
for (i = 0; i < N; i++)
if (output[i] != check_results[i] || output2[i] != check_results2[i])
abort ();
return 0;
}
-/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" { target
vect_perm } } } */
+/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 2 "vect" { target
vect_perm } } } */
/* { dg-final { scan-tree-dump-times "vectorizing stmts using SLP" 1 "vect" {
target vect_perm } } } */
/* { dg-final { cleanup-tree-dump "vect" } } */
Index: gcc/tree-vrp.c
===================================================================
--- gcc/tree-vrp.c (revision 222708)
+++ gcc/tree-vrp.c (working copy)
@@ -3189,40 +3189,83 @@ extract_range_from_binary_expr_1 (value_
}
}
else
{
extract_range_from_multiplicative_op_1 (vr, code, &vr0, &vr1);
return;
}
}
else if (code == TRUNC_MOD_EXPR)
{
- if (vr1.type != VR_RANGE
- || range_includes_zero_p (vr1.min, vr1.max) != 0
- || vrp_val_is_min (vr1.min))
+ if (range_is_null (&vr1))
+ {
+ set_value_range_to_undefined (vr);
+ return;
+ }
+ // Some propagation of symbolic ranges should be possible
+ // at least in the unsigned case.
+ bool has_vr0 = vr0.type == VR_RANGE && !symbolic_range_p (&vr0);
+ bool has_vr1 = vr1.type == VR_RANGE && !symbolic_range_p (&vr1);
+ if (!has_vr0 && !has_vr1)
{
set_value_range_to_varying (vr);
return;
}
type = VR_RANGE;
- /* Compute MAX <|vr1.min|, |vr1.max|> - 1. */
- max = fold_unary_to_constant (ABS_EXPR, expr_type, vr1.min);
- if (tree_int_cst_lt (max, vr1.max))
- max = vr1.max;
- max = int_const_binop (MINUS_EXPR, max, build_int_cst (TREE_TYPE (max),
1));
- /* If the dividend is non-negative the modulus will be
- non-negative as well. */
- if (TYPE_UNSIGNED (expr_type)
- || value_range_nonnegative_p (&vr0))
- min = build_int_cst (TREE_TYPE (max), 0);
+ if (TYPE_UNSIGNED (expr_type))
+ {
+ // A % B is at most A and smaller than B.
+ min = build_int_cst (expr_type, 0);
+ if (has_vr0 && (!has_vr1 || tree_int_cst_lt (vr0.max, vr1.max)))
+ max = vr0.max;
+ else
+ max = int_const_binop (MINUS_EXPR, vr1.max,
+ build_int_cst (expr_type, 1));
+ }
else
- min = fold_unary_to_constant (NEGATE_EXPR, expr_type, max);
+ {
+ tree min1 = NULL_TREE;
+ tree max1 = NULL_TREE;
+ if (has_vr1)
+ {
+ // ABS (A % B) < ABS (B)
+ max1 = fold_unary_to_constant (ABS_EXPR, expr_type, vr1.min);
+ if (tree_int_cst_lt (max1, vr1.max))
+ max1 = vr1.max;
+ max1 = int_const_binop (MINUS_EXPR, max1,
+ build_int_cst (expr_type, 1));
+ min1 = fold_unary_to_constant (NEGATE_EXPR, expr_type, max1);
+ }
+ if (has_vr0)
+ {
+ // Either 0 <= A % B <= A or A <= A % B <= 0.
+ max = vr0.max;
+ min = vr0.min;
+ tree zero = build_int_cst (expr_type, 0);
+ if (tree_int_cst_lt (zero, min))
+ min = zero;
+ if (tree_int_cst_lt (max, zero))
+ max = zero;
+ if (has_vr1)
+ {
+ if (tree_int_cst_lt (min, min1))
+ min = min1;
+ if (tree_int_cst_lt (max1, max))
+ max = max1;
+ }
+ }
+ else
+ {
+ min = min1;
+ max = max1;
+ }
+ }
}
else if (code == BIT_AND_EXPR || code == BIT_IOR_EXPR || code ==
BIT_XOR_EXPR)
{
bool int_cst_range0, int_cst_range1;
wide_int may_be_nonzero0, may_be_nonzero1;
wide_int must_be_nonzero0, must_be_nonzero1;
int_cst_range0 = zero_nonzero_bits_from_vr (expr_type, &vr0,
&may_be_nonzero0,
&must_be_nonzero0);
