Hi!
build_array_type_nelts is only meaningful for non-zero number of elements,
for 0 it creates weirdo arrays like char D.2358[0:18446744073709551615].
The following patch uses in that case types like the C FE emits for
zero-length array instead (i.e. char D.2358[0:] with forced 0 size).
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2019-09-24 Jakub Jelinek <ja...@redhat.com>
PR sanitizer/91707
* tree-ssa-ccp.c (fold_builtin_alloca_with_align): For n_elem 0
use a type like C zero length array instead of array from 0
to SIZE_MAX.
--- gcc/tree-ssa-ccp.c.jj 2019-09-20 12:25:26.809718354 +0200
+++ gcc/tree-ssa-ccp.c 2019-09-23 19:38:03.530722874 +0200
@@ -2223,7 +2223,18 @@ fold_builtin_alloca_with_align (gimple *
/* Declare array. */
elem_type = build_nonstandard_integer_type (BITS_PER_UNIT, 1);
n_elem = size * 8 / BITS_PER_UNIT;
- array_type = build_array_type_nelts (elem_type, n_elem);
+ if (n_elem == 0)
+ {
+ /* For alloca (0), use array type similar to C zero-length arrays. */
+ tree range_type = build_range_type (sizetype, size_zero_node, NULL_TREE);
+ array_type = build_array_type (elem_type, range_type);
+ array_type = build_distinct_type_copy (TYPE_MAIN_VARIANT (array_type));
+ TYPE_SIZE (array_type) = bitsize_zero_node;
+ TYPE_SIZE_UNIT (array_type) = size_zero_node;
+ SET_TYPE_STRUCTURAL_EQUALITY (array_type);
+ }
+ else
+ array_type = build_array_type_nelts (elem_type, n_elem);
var = create_tmp_var (array_type);
SET_DECL_ALIGN (var, TREE_INT_CST_LOW (gimple_call_arg (stmt, 1)));
if (uid != 0)
Jakub
