Hi!
The function calls get_addr_base_and_unit_offset on 2 trees, but
that can return NULL if the unit offset is not constant.
The conditional tests just one of them for non-NULL and operand_equal_p
ICEs if one argument is NULL, so depending on the uninitialized poly_int64
(get_addr_base_and_unit_offset doesn't touch it if it returns NULL),
we either ICE in operand_equal_p or are lucky and dstoff is equal to lhsoff
and just valgrind complains.
Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
trunk?
2018-02-15 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/84383
* tree-ssa-strlen.c (maybe_diag_stxncpy_trunc): Don't look at
dstoff nor call operand_equal_p if dstbase is NULL.
* gcc.c-torture/compile/pr84383.c: New test.
--- gcc/tree-ssa-strlen.c.jj 2018-02-09 06:44:29.993809176 +0100
+++ gcc/tree-ssa-strlen.c 2018-02-14 16:38:36.981713666 +0100
@@ -1878,6 +1878,7 @@ maybe_diag_stxncpy_trunc (gimple_stmt_it
poly_int64 lhsoff;
tree lhsbase = get_addr_base_and_unit_offset (lhs, &lhsoff);
if (lhsbase
+ && dstbase
&& known_eq (dstoff, lhsoff)
&& operand_equal_p (dstbase, lhsbase, 0))
return false;
--- gcc/testsuite/gcc.c-torture/compile/pr84383.c.jj 2018-02-14
17:33:21.972803287 +0100
+++ gcc/testsuite/gcc.c-torture/compile/pr84383.c 2018-02-14
17:32:37.639803918 +0100
@@ -0,0 +1,14 @@
+/* PR tree-optimization/84383 */
+
+struct S { char *s; };
+void bar (struct S *);
+
+void
+foo (int a, char *b)
+{
+ struct S c[4];
+ bar (c);
+ __builtin_strncpy (c[a].s, b, 32);
+ c[a].s[31] = '\0';
+ bar (c);
+}
Jakub
