https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87561
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization
CC| |rsandifo at gcc dot gnu.org
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Another thing is the too complicated alias check where for
(gdb) p debug_data_reference (dr_a.dr)
#(Data Ref:
# bb: 14
# stmt: _28 = *xpqkl_172(D)[_27];
# ref: *xpqkl_172(D)[_27];
# base_object: *xpqkl_172(D);
# Access function 0: {(((integer(kind=8)) mkl_203 + 1) * stride.33_148 +
offset.34_149) + _480, +, stride.33_148}_6
#)
$9 = void
(gdb) p debug_data_reference (dr_b.dr)
#(Data Ref:
# bb: 14
# stmt: *xpqkl_172(D)[_50] = _65;
# ref: *xpqkl_172(D)[_50];
# base_object: *xpqkl_172(D);
# Access function 0: {(((integer(kind=8)) mkl_203 + 1) * stride.33_148 +
offset.34_149) + _486, +, stride.33_148}_6
#)
we generate
(ssizetype) (((sizetype) ((((integer(kind=8)) mkl_203 + 1) * stride.33_148 +
offset.34_149) + (integer(kind=8)) (_19 + jpack_161)) + (sizetype)
stride.33_148) * 8) < (ssizetype) ((sizetype) ((((integer(kind=8)) mkl_203 + 1)
* stride.33_148 + offset.34_149) + (integer(kind=8)) (_22 + lpack_164)) * 8) ||
(ssizetype) (((sizetype) ((((integer(kind=8)) mkl_203 + 1) * stride.33_148 +
offset.34_149) + (integer(kind=8)) (_22 + lpack_164)) + (sizetype)
stride.33_148) * 8) < (ssizetype) ((sizetype) ((((integer(kind=8)) mkl_203 + 1)
* stride.33_148 + offset.34_149) + (integer(kind=8)) (_19 + jpack_161)) * 8)
instead of simply _480 != _486 (well, OK, not _that_ simple).
I guess we miss many of the "optimizations" we do when dealing with
alias checks for constant steps. In this case sth obvious would be
to special-case DR_STEP (dra) == DR_STEP (drb). Richard?
