http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50444
--- Comment #16 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-01-20
15:46:40 UTC ---
(In reply to comment #15)
> Created attachment 26395 [details]
> other candidate patch
>
> I'm testing the following patch instead, which avoids changing access types
> for all-scalar across-link propagations (we're going to create proper V_C_Es
> later). I also remove the fancy code that tries to avoid adding V_C_Es,
> it looks it will cause more trouble than missed-optimizations.
>
> That way we completely avoid needing to care for alignment at that particular
> places. Whether the aggregate copy across-link propagation is affected in
> a similar way remains to be seen.
>
> I'll see if I run into the same issue as you and investigate that.
gcc.dg/torture/pr47228.c shows that we rely on the build-ref-for-model
path in sra_modify_assign as we scalarize
struct S4
{
unsigned f0:24;
} __attribute__((__packed__));
to unsigned int : 24, which is of different size, so we refuse to
VIEW_CONVERT the SImode register to BLKmode. I'm not entirely sure
what's the best cause of action here, but certainly either detecting
the size-mismatch issue at analysis phase or papering over the issue
with build-ref-for-model (which might not always suceed?!).
Other FAILs this patch causes are
Running target unix/
FAIL: gcc.dg/tree-ssa/pr45144.c scan-tree-dump optimized " =
VIEW_CONVERT_EXPR<u
nsigned int>\\(a\\);"
Running target unix/-m32
FAIL: gcc.dg/torture/pr45678-2.c -Os execution test
FAIL: gcc.dg/tree-ssa/pr45144.c scan-tree-dump optimized " =
VIEW_CONVERT_EXPR<u
nsigned int>\\(a\\);"
Running target unix/
FAIL: 20_util/hash/chi2_quality.cc execution test
FAIL: 23_containers/forward_list/capacity/resize_size.cc execution test
FAIL: 23_containers/forward_list/modifiers/2.cc execution test
FAIL: 23_containers/list/operations/3.cc execution test
FAIL: 23_containers/list/operations/3_c++0x.cc execution test
FAIL: ext/pb_ds/example/basic_map.cc execution test
FAIL: ext/pb_ds/example/basic_multiset.cc execution test
FAIL: ext/pb_ds/example/basic_set.cc execution test
FAIL: ext/pb_ds/example/erase_if.cc execution test
FAIL: ext/pb_ds/example/tree_intervals.cc execution test
FAIL: ext/pb_ds/example/tree_join.cc execution test
FAIL: ext/pb_ds/example/tree_order_statistics.cc execution test
FAIL: ext/pb_ds/regression/associative_containers.cc execution test
FAIL: ext/pb_ds/regression/tree_map_rand.cc execution test
FAIL: ext/pb_ds/regression/tree_set_rand.cc execution test
Running target unix//-m32
FAIL: 23_containers/list/operations/3_c++0x.cc execution test
FAIL: 25_algorithms/nth_element/2.cc execution test
I'm going to test the two parts of the patch separately now.
