https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107047
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2022-09-27
Keywords| |missed-optimization
Known to fail| |12.2.1, 13.0
Ever confirmed|0 |1
Component|rtl-optimization |middle-end
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed, we see
<bb 2> [local count: 1073741824]:
f[1][6] = g_36;
_1 = BIT_FIELD_REF <f[1][6], 32, 0>;
_8 = _1 & 16777215;
if (_8 != 0)
VN probably sees the def but it doesn't consider replacing the use with
a BIT_FIELD_REF of g_36, it just translates the ref but doesn't find
any definition to CSE from.
SRA says
Candidate (1991): f
Too big to totally scalarize: f (UID: 1991)
Created a replacement for f offset: 848, size: 8: f$1$6$f1D.1996
Access trees for f (UID: 1991):
access { base = (1991)'f', offset = 832, size = 64, expr = f[1][6], type =
struct S6, reverse = 0, grp_read = 1, grp_write = 1, grp_assignment_read = 1,
grp_assignment_write = 1, grp_scalar_read = 0, grp_scalar_write = 0,
grp_total_scalarization = 0, grp_hint = 0, grp_covered = 0,
grp_unscalarizable_region = 0, grp_unscalarized_data = 1, grp_same_access_path
= 1, grp_partial_lhs = 0, grp_to_be_replaced = 0, grp_to_be_debug_replaced = 0}
* access { base = (1991)'f', offset = 848, size = 8, expr = f[1][6].f1, type =
char, reverse = 0, grp_read = 1, grp_write = 1, grp_assignment_read = 1,
grp_assignment_write = 1, grp_scalar_read = 1, grp_scalar_write = 0,
grp_total_scalarization = 0, grp_hint = 0, grp_covered = 1,
grp_unscalarizable_region = 0, grp_unscalarized_data = 0, grp_same_access_path
= 1, grp_partial_lhs = 0, grp_to_be_replaced = 1, grp_to_be_debug_replaced = 0}
but somehow it does not create an access for
_1 = BIT_FIELD_REF <f[1][6], 32, 0>;
_2 = (unsigned int) _1;
note the real offender here is (again) optimize_bit_field_compare ...
