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| author | Richard Sandiford <richard.sandiford@arm.com> | 2020-02-18 18:06:32 +0000 |
|---|---|---|
| committer | Richard Sandiford <richard.sandiford@arm.com> | 2020-02-19 13:12:22 +0000 |
| commit | f91aa3e6cb808f8dfc6b45fa135f7583a7549161 (patch) | |
| tree | df517321d86e31f94c6bb925803180716b53634c /gcc | |
| parent | aca60ecff35837a1af9383cf67ee7d1c0a718b28 (diff) | |
| download | gcc-f91aa3e6cb808f8dfc6b45fa135f7583a7549161.zip gcc-f91aa3e6cb808f8dfc6b45fa135f7583a7549161.tar.gz gcc-f91aa3e6cb808f8dfc6b45fa135f7583a7549161.tar.bz2 | |
vect: Fix offset calculation for -ve strides [PR93767]
This PR is a regression caused by r256644, which added support for alias
checks involving variable strides. One of the changes in that commit
was to split the access size out of the segment length. The PR shows
that I hadn't done that correctly for the handling of negative strides
in vect_compile_time_alias. The old code was:
const_length_a = (-wi::to_poly_wide (segment_length_a)).force_uhwi ();
offset_a = (offset_a + vect_get_scalar_dr_size (a)) - const_length_a;
where vect_get_scalar_dr_size (a) was cancelling out the subtraction
of the access size inherent in "- const_length_a". Taking the access
size out of the segment length meant that the addition was no longer
needed/correct.
2020-02-19 Richard Sandiford <richard.sandiford@arm.com>
gcc/
PR tree-optimization/93767
* tree-vect-data-refs.c (vect_compile_time_alias): Remove the
access-size bias from the offset calculations for negative strides.
gcc/testsuite/
PR tree-optimization/93767
* gcc.dg/vect/pr93767.c: New test.
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ChangeLog | 6 | ||||
| -rw-r--r-- | gcc/testsuite/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.dg/vect/pr93767.c | 13 | ||||
| -rw-r--r-- | gcc/tree-vect-data-refs.c | 4 |
4 files changed, 26 insertions, 2 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 6cd941a..757d05a 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2020-02-19 Richard Sandiford <richard.sandiford@arm.com> + + PR tree-optimization/93767 + * tree-vect-data-refs.c (vect_compile_time_alias): Remove the + access-size bias from the offset calculations for negative strides. + 2020-02-19 Bernd Edlinger <bernd.edlinger@hotmail.de> * collect2.c (c_file, o_file): Make const again. diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index df79951..2d88138 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2020-02-19 Richard Sandiford <richard.sandiford@arm.com> + + PR tree-optimization/93767 + * gcc.dg/vect/pr93767.c: New test. + 2020-02-19 Martin Jambor <mjambor@suse.cz> PR tree-optimization/93776 diff --git a/gcc/testsuite/gcc.dg/vect/pr93767.c b/gcc/testsuite/gcc.dg/vect/pr93767.c new file mode 100644 index 0000000..5f95d7b --- /dev/null +++ b/gcc/testsuite/gcc.dg/vect/pr93767.c @@ -0,0 +1,13 @@ +int +main () +{ + int a[10], b; + for (b = 6; b >= 3; b--) + { + a[b] = 1; + a[b + 2] = a[3]; + } + if (a[5] != 1) + __builtin_abort (); + return 0; +} diff --git a/gcc/tree-vect-data-refs.c b/gcc/tree-vect-data-refs.c index 554ef89..0192aa6 100644 --- a/gcc/tree-vect-data-refs.c +++ b/gcc/tree-vect-data-refs.c @@ -3261,14 +3261,14 @@ vect_compile_time_alias (dr_vec_info *a, dr_vec_info *b, if (tree_int_cst_compare (DR_STEP (a->dr), size_zero_node) < 0) { const_length_a = (-wi::to_poly_wide (segment_length_a)).force_uhwi (); - offset_a = (offset_a + access_size_a) - const_length_a; + offset_a -= const_length_a; } else const_length_a = tree_to_poly_uint64 (segment_length_a); if (tree_int_cst_compare (DR_STEP (b->dr), size_zero_node) < 0) { const_length_b = (-wi::to_poly_wide (segment_length_b)).force_uhwi (); - offset_b = (offset_b + access_size_b) - const_length_b; + offset_b -= const_length_b; } else const_length_b = tree_to_poly_uint64 (segment_length_b); |