https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114151
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2024-02-28
Ever confirmed|0 |1
CC| |amacleod at redhat dot com,
| |rsandifo at gcc dot gnu.org
Target Milestone|--- |14.0
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Do we have POLY_INT_CSTs in CHRECs? Huh, yeah - we do. So in IVOPTs the
differences are like
(get_scalar_evolution
(scalar = col_i_61)
- (scalar_evolution = {iftmp.0_11 * _105, +, iftmp.0_11}_2))
+ (scalar_evolution = (int) {(unsigned int) col_stride_10 * (unsigned int)
_105, +, (unsigned int) col_stride_10}_2))
but also
(set_scalar_evolution
instantiated_below = 22
(scalar = _58)
- (scalar_evolution = {(__fp16 *) p_mat_16(D) + ((long unsigned int) _105 +
(long unsigned int) (iftmp.0_11 * _105)) * 2, +, ((long unsigned int)
iftmp.0_11 + 1) * 2}_2))
+ (scalar_evolution = _58))
(that's completely missed)
Likewise, with POLY_INT_CST:
- (scalar_evolution = {(__fp16 *) p_mat_16(D) + (((long unsigned int)
(iftmp.0_11 * _105) + (long unsigned int) _105) * 2 + POLY_INT_CST [16, 16]),
+, ((long unsigned int) iftmp.0_11 + 1) * 2}_2))
+ (scalar_evolution = _13))
The special-casing of CHREC * x we allow to be expressed works by looking
at value-ranges and signs of INTEGER_CSTs:
+ if (!ANY_INTEGRAL_TYPE_P (type)
+ || TYPE_OVERFLOW_WRAPS (type)
+ || integer_zerop (CHREC_LEFT (op0))
+ || (TREE_CODE (CHREC_LEFT (op0)) == INTEGER_CST
+ && TREE_CODE (CHREC_RIGHT (op0)) == INTEGER_CST
+ && (tree_int_cst_sgn (CHREC_LEFT (op0))
+ == tree_int_cst_sgn (CHREC_RIGHT (op0))))
+ || (get_range_query (cfun)->range_of_expr (rl, CHREC_LEFT (op0
...
possibly there might be a way to adapt the "same sign" check to also work
for POLY_INT_CSTs which I think have known signs? Possibly rewriting
that by using poly_int_tree_p () isntead of checking for INTEGER_CST
and then using known_lt (wi::to_poly_wide (), 0) && known_lt (..., 0)
|| known_gt (..., 0) && known_gt (..., 0) helps?
Nope, the following doesn't make a difference here.
diff --git a/gcc/tree-chrec.cc b/gcc/tree-chrec.cc
index 2e6c7356d3b..366ab914c8f 100644
--- a/gcc/tree-chrec.cc
+++ b/gcc/tree-chrec.cc
@@ -442,10 +442,12 @@ chrec_fold_multiply (tree type,
if (!ANY_INTEGRAL_TYPE_P (type)
|| TYPE_OVERFLOW_WRAPS (type)
|| integer_zerop (CHREC_LEFT (op0))
- || (TREE_CODE (CHREC_LEFT (op0)) == INTEGER_CST
- && TREE_CODE (CHREC_RIGHT (op0)) == INTEGER_CST
- && (tree_int_cst_sgn (CHREC_LEFT (op0))
- == tree_int_cst_sgn (CHREC_RIGHT (op0))))
+ || (poly_int_tree_p (CHREC_LEFT (op0))
+ && poly_int_tree_p (CHREC_RIGHT (op0))
+ && ((known_lt (wi::to_poly_widest (CHREC_LEFT (op0)), 0)
+ && known_lt (wi::to_poly_widest (CHREC_RIGHT (op0)), 0))
+ || (known_ge (wi::to_poly_widest (CHREC_LEFT (op0)), 0)
+ && known_ge (wi::to_poly_widest (CHREC_RIGHT (op0)),
0))))
|| (get_range_query (cfun)->range_of_expr (rl, CHREC_LEFT (op0))
&& !rl.undefined_p ()
&& (rl.nonpositive_p () || rl.nonnegative_p ())
This was a correctness fix btw, so I'm not sure we can easily recover - we
could try using niter information for CHREC_VARIABLE but then there's
variable niter here so I don't see a chance.
This is mainly IVs like
col_i_61 = col_stride_10 * j_73;
_60 = (long unsigned int) col_i_61;
_59 = _60 * 2;
_58 = a_j_69 + _59;
_54 = MEM <__SVFloat16_t> [(__fp16 *)_58];
where we compose for example the scalar evolution of col_i_61 by
multiplyinig that of j_73 which is {_105, +, 1}_2 with col_stride_10.
Possibly adding a ranger instance to IVOPTs could help, for this instance
since
<bb 4> [local count: 118111600]:
# col_stride_10 = PHI <size_15(D)(11), 1(2)>
if (size_15(D) > 0)
goto <bb 21>; [89.00%]
else
goto <bb 5>; [11.00%]
<bb 5> [local count: 118111600]:
return;
so col_stride_10 should be positive, and _105 as well:
_12 = MAX_EXPR <_103, 0>;
_3 = (unsigned int) _12;
_4 = _3 + 1;
_105 = (int) _4;
OTOH the +1 could make it overflow for large size.
Can you test the above? It should be an incremental improvement.
Adding enable_ranger (cfun); / disable_ranger (cfun); around the IVOPTs
pass doesn't seem to help (but see above - there might not be enough
info, also the code added doesn't pass in a context stmt so ranger
might not do much/anything here).
Confirmed.
