This fixes a missed optimization in EVRP by teaching the code
figuring out conditional asserts about conversions that preserve
the converted value.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk
sofar.
Richard.
2018-12-03 Richard Biener <rguent...@suse.de>
PR tree-optimization/88301
* tree-vrp.c (register_edge_assert_for_2): Handle conversions
that do not change the value by registering the same assert
for the operand.
* gcc.dg/tree-ssa/evrp13.c: New testcase.
Index: gcc/tree-vrp.c
===================================================================
--- gcc/tree-vrp.c (revision 266733)
+++ gcc/tree-vrp.c (working copy)
@@ -2966,6 +2966,23 @@ register_edge_assert_for_2 (tree name, e
add_assert_info (asserts, name2, tmp, new_comp_code, new_val);
}
+ /* If we have a conversion that doesn't change the value of the source
+ simply register the same assert for it. */
+ if (CONVERT_EXPR_CODE_P (rhs_code))
+ {
+ wide_int rmin, rmax;
+ tree rhs1 = gimple_assign_rhs1 (def_stmt);
+ if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
+ && int_fits_type_p (val, TREE_TYPE (rhs1))
+ && ((TYPE_PRECISION (TREE_TYPE (name))
+ > TYPE_PRECISION (TREE_TYPE (rhs1)))
+ || (get_range_info (rhs1, &rmin, &rmax) == VR_RANGE
+ && wi::fits_to_tree_p (rmin, TREE_TYPE (name))
+ && wi::fits_to_tree_p (rmax, TREE_TYPE (name)))))
+ add_assert_info (asserts, rhs1, rhs1,
+ comp_code, fold_convert (TREE_TYPE (rhs1), val));
+ }
+
/* Add asserts for NAME cmp CST and NAME being defined as
NAME = NAME2 & CST2.
Index: gcc/testsuite/gcc.dg/tree-ssa/evrp13.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/evrp13.c (revision 0)
+++ gcc/testsuite/gcc.dg/tree-ssa/evrp13.c (working copy)
@@ -0,0 +1,7 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-evrp" } */
+
+#define ADD_NW(A,B) (__extension__({ __typeof(A+B) R;
if(__builtin_add_overflow(A,B,&R)) __builtin_unreachable(); R ;}))
+_Bool a_b2(unsigned A, unsigned B) { return ADD_NW(A,B) >= B; }
+
+/* { dg-final { scan-tree-dump "return 1;" "evrp" } } */
