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| author | Richard Guenther <rguenther@suse.de> | 2011-10-05 14:35:15 +0000 |
|---|---|---|
| committer | Richard Biener <rguenth@gcc.gnu.org> | 2011-10-05 14:35:15 +0000 |
| commit | c867aba0c04643ea47cec651cb270e6d09c17f28 (patch) | |
| tree | 3088e902d6379ea1f7ad70c2358f94e554dcb80d /gcc/tree-ssa-sccvn.c | |
| parent | 484db665a35edd7c5e4112331665da4dfe57affd (diff) | |
| download | gcc-c867aba0c04643ea47cec651cb270e6d09c17f28.zip gcc-c867aba0c04643ea47cec651cb270e6d09c17f28.tar.gz gcc-c867aba0c04643ea47cec651cb270e6d09c17f28.tar.bz2 | |
re PR tree-optimization/38885 (missed FRE with BIT_FIELD_REF and vectors)
2011-10-05 Richard Guenther <rguenther@suse.de>
PR tree-optimization/38885
* tree-ssa-sccvn.c (vn_reference_lookup_3): Handle partial reads
from constants.
* gcc.dg/tree-ssa/ssa-fre-33.c: New testcase.
From-SVN: r179556
Diffstat (limited to 'gcc/tree-ssa-sccvn.c')
| -rw-r--r-- | gcc/tree-ssa-sccvn.c | 51 |
1 files changed, 49 insertions, 2 deletions
diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c index 4b5d388..3b1ad3d 100644 --- a/gcc/tree-ssa-sccvn.c +++ b/gcc/tree-ssa-sccvn.c @@ -1442,7 +1442,54 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *vr_) } } - /* 3) For aggregate copies translate the reference through them if + /* 3) Assignment from a constant. We can use folds native encode/interpret + routines to extract the assigned bits. */ + else if (CHAR_BIT == 8 && BITS_PER_UNIT == 8 + && ref->size == maxsize + && maxsize % BITS_PER_UNIT == 0 + && offset % BITS_PER_UNIT == 0 + && is_gimple_reg_type (vr->type) + && gimple_assign_single_p (def_stmt) + && is_gimple_min_invariant (gimple_assign_rhs1 (def_stmt))) + { + tree base2; + HOST_WIDE_INT offset2, size2, maxsize2; + base2 = get_ref_base_and_extent (gimple_assign_lhs (def_stmt), + &offset2, &size2, &maxsize2); + if (maxsize2 != -1 + && maxsize2 == size2 + && size2 % BITS_PER_UNIT == 0 + && offset2 % BITS_PER_UNIT == 0 + && operand_equal_p (base, base2, 0) + && offset2 <= offset + && offset2 + size2 >= offset + maxsize) + { + /* We support up to 512-bit values (for V8DFmode). */ + unsigned char buffer[64]; + int len; + + len = native_encode_expr (gimple_assign_rhs1 (def_stmt), + buffer, sizeof (buffer)); + if (len > 0) + { + tree val = native_interpret_expr (vr->type, + buffer + + ((offset - offset2) + / BITS_PER_UNIT), + ref->size / BITS_PER_UNIT); + if (val) + { + unsigned int value_id = get_or_alloc_constant_value_id (val); + return vn_reference_insert_pieces + (vuse, vr->set, vr->type, + VEC_copy (vn_reference_op_s, heap, vr->operands), + val, value_id); + } + } + } + } + + /* 4) For aggregate copies translate the reference through them if the copy kills ref. */ else if (vn_walk_kind == VN_WALKREWRITE && gimple_assign_single_p (def_stmt) @@ -1540,7 +1587,7 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *vr_) return NULL; } - /* 4) For memcpy copies translate the reference through them if + /* 5) For memcpy copies translate the reference through them if the copy kills ref. */ else if (vn_walk_kind == VN_WALKREWRITE && is_gimple_reg_type (vr->type) |