diff options
| author | Richard Biener <rguenther@suse.de> | 2019-07-23 10:00:24 +0000 |
|---|---|---|
| committer | Richard Biener <rguenth@gcc.gnu.org> | 2019-07-23 10:00:24 +0000 |
| commit | 62e3e66f130fc280eac0bbb6b69e9adca328c03b (patch) | |
| tree | 83ec6d9b0fd5b3a0800a0d673c2e9204136fe1ff /gcc/tree-ssa-sccvn.c | |
| parent | e1eb82f5aa4f6e9ed9a6a368b54d0eda785be85c (diff) | |
re PR tree-optimization/83518 (Missing optimization: useless instructions should be dropped)
2019-07-23 Richard Biener <rguenther@suse.de>
PR tree-optimization/83518
* tree-ssa-sccvn.c (vn_reference_lookup_3): Handle aggregate
init from a constant even when partial defs are already recorded.
c/
* gimple-parser.c (c_parser_parse_gimple_body): When we have
a CFG also rebuild cgraph edges.
* gcc.dg/tree-ssa/ssa-fre-79.c: New testcase.
From-SVN: r273732
Diffstat (limited to 'gcc/tree-ssa-sccvn.c')
| -rw-r--r-- | gcc/tree-ssa-sccvn.c | 30 |
1 files changed, 25 insertions, 5 deletions
diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c index cab2460a308..9369c36f50e 100644 --- a/gcc/tree-ssa-sccvn.c +++ b/gcc/tree-ssa-sccvn.c @@ -2702,9 +2702,7 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_, && gimple_assign_single_p (def_stmt) && (DECL_P (gimple_assign_rhs1 (def_stmt)) || TREE_CODE (gimple_assign_rhs1 (def_stmt)) == MEM_REF - || handled_component_p (gimple_assign_rhs1 (def_stmt))) - /* Handling this is more complicated, give up for now. */ - && data->partial_defs.is_empty ()) + || handled_component_p (gimple_assign_rhs1 (def_stmt)))) { tree base2; int i, j, k; @@ -2808,8 +2806,30 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_, /* Try folding the new reference to a constant. */ tree val = fully_constant_vn_reference_p (vr); if (val) - return vn_reference_lookup_or_insert_for_pieces - (vuse, vr->set, vr->type, vr->operands, val); + { + if (data->partial_defs.is_empty ()) + return vn_reference_lookup_or_insert_for_pieces + (vuse, vr->set, vr->type, vr->operands, val); + /* This is the only interesting case for partial-def handling + coming from targets that like to gimplify init-ctors as + aggregate copies from constant data like aarch64 for + PR83518. */ + if (maxsize.is_constant (&maxsizei) + && known_eq (ref->size, maxsize)) + { + pd_data pd; + pd.rhs = val; + pd.offset = 0; + pd.size = maxsizei / BITS_PER_UNIT; + return data->push_partial_def (pd, vuse, maxsizei); + } + } + + /* Continuing with partial defs isn't easily possible here, we + have to find a full def from further lookups from here. Probably + not worth the special-casing everywhere. */ + if (!data->partial_defs.is_empty ()) + return (void *)-1; /* Adjust *ref from the new operands. */ if (!ao_ref_init_from_vn_reference (&r, vr->set, vr->type, vr->operands)) |