Hi Jakub and/or Joseph, the reporter of this bug seems to be very anxious to have it fixed in the repository. While Richi is away, do you think you could have a look? It is very small.
Thanks a lot, Martin On Fri, Aug 02, 2013 at 01:45:31PM +0200, Martin Jambor wrote: > Hi, > > while compute_record_mode in stor-layout.c makes sure it assigns BLK > mode to structs with flexible arrays, it has no such provisions for > zero length arrays > (http://gcc.gnu.org/onlinedocs/gcc-4.8.1/gcc/Zero-Length.html). I > think that in order to avoid problems and surprises like PR 57748 > (where this triggered code that was intended for small structures that > fit into a scalar mode and ICEd), we should assign both variable array > possibilities the same mode. > > Bootstrapped and tested on x86_64-linux without any problems. OK for > trunk and the 4.8 branch? (I'm not sure about the 4.7, this PR does > not happen there despite the wrong mode so I'd ignore it for now.) > > Thanks, > > Martin > > > 2013-08-01 Martin Jambor <mjam...@suse.cz> > > PR middle-end/57748 > * stor-layout.c (compute_record_mode): Treat zero-sized array fields > like incomplete types. > > testsuite/ > * gcc.dg/torture/pr57748.c: New test. > > > *** /tmp/lV6Ba8_stor-layout.c Thu Aug 1 16:28:25 2013 > --- gcc/stor-layout.c Thu Aug 1 15:36:18 2013 > *************** compute_record_mode (tree type) > *** 1604,1610 **** > && integer_zerop (TYPE_SIZE (TREE_TYPE (field))))) > || ! host_integerp (bit_position (field), 1) > || DECL_SIZE (field) == 0 > ! || ! host_integerp (DECL_SIZE (field), 1)) > return; > > /* If this field is the whole struct, remember its mode so > --- 1604,1612 ---- > && integer_zerop (TYPE_SIZE (TREE_TYPE (field))))) > || ! host_integerp (bit_position (field), 1) > || DECL_SIZE (field) == 0 > ! || ! host_integerp (DECL_SIZE (field), 1) > ! || (TREE_CODE (TREE_TYPE (field)) == ARRAY_TYPE > ! && tree_low_cst (DECL_SIZE (field), 1) == 0)) > return; > > /* If this field is the whole struct, remember its mode so > *** /dev/null Tue Jun 4 12:34:56 2013 > --- gcc/testsuite/gcc.dg/torture/pr57748.c Thu Aug 1 15:42:14 2013 > *************** > *** 0 **** > --- 1,45 ---- > + /* PR middle-end/57748 */ > + /* { dg-do run } */ > + > + #include <stdlib.h> > + > + extern void abort (void); > + > + typedef long long V > + __attribute__ ((vector_size (2 * sizeof (long long)), may_alias)); > + > + typedef struct S { V a; V b[0]; } P __attribute__((aligned (1))); > + > + struct __attribute__((packed)) T { char c; P s; }; > + > + void __attribute__((noinline, noclone)) > + check (struct T *t) > + { > + if (t->s.b[0][0] != 3 || t->s.b[0][1] != 4) > + abort (); > + } > + > + int __attribute__((noinline, noclone)) > + get_i (void) > + { > + return 0; > + } > + > + void __attribute__((noinline, noclone)) > + foo (P *p) > + { > + V a = { 3, 4 }; > + int i = get_i(); > + p->b[i] = a; > + } > + > + int > + main () > + { > + struct T *t = (struct T *) malloc (128); > + > + foo (&t->s); > + check (t); > + > + return 0; > + }
