https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102238
Bug ID: 102238
Summary: alias_offset in gimple-ssa-sprintf.c is broken
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Keywords: diagnostic
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: pinskia at gcc dot gnu.org
Target Milestone: ---
Take:
/*
{ dg-do compile }
{ dg-options "-O2 -Wno-format-overflow -Wrestrict -ftrack-macro-expansion=0"
}
*/
void sink (int);
#define S10 "0123456789"
extern char a2[2][22];
#define T(d, ...) do { \
char a[22] = S10; \
sink (__builtin_sprintf ((d), __VA_ARGS__)); \
} while (0)
struct S {
char a[4];
char b[4];
};
struct S2 {
struct S s_1;
struct S s_2;
struct S sa3[3];
};
struct S3 {
struct S2 s2_1;
struct S2 s2_2;
struct {
struct {
struct {
struct S sa_3[3];
} a_1[3];
} a_2[3][3];
} a_3[3][3][3];
char fa[];
};
void test_struct_member_array (struct S3 *s3, int i)
{
char *a = (char*)s3;
char *d;
const char *s;
d = s3->s2_2.s_1.a;
s = s3->s2_2.s_1.a;
T (d, "%s", a + 40); /* { dg-warning "overlaps" } */
T (d, "%s", a + 41); /* { dg-warning "may overlap" } */
T (d, "%s", a + 42); /* { dg-warning "may overlap" } */
}
----- CUT -----
This should warn but does not.
The reason is alias_offset does not do a good job at all figuring out field
offsets.
