https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91732
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization, openmp
Status|UNCONFIRMED |NEW
Last reconfirmed| |2019-09-11
CC| |jakub at gcc dot gnu.org
Component|c |tree-optimization
Blocks| |53947
Ever confirmed|0 |1
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
The runtime alias test is between the two stores of the inner unrolled loop.
That's dv[i] vs. dv[i+Q].
Creating dr for *_61
analyze_innermost: success.
base_address: dv_44(D)
offset from base address: 0
constant offset from base address: 0
step: 8
base alignment: 8
base misalignment: 0
offset alignment: 512
step alignment: 8
base_object: *dv_44(D)
Access function 0: {0B, +, 8}_1
Creating dr for *_79
analyze_innermost: success.
base_address: (double *) dv_44(D) + (sizetype) ((long unsigned int)
Q_35(D) * 8)
offset from base address: 0
constant offset from base address: 0
step: 8
base alignment: 8
base misalignment: 0
offset alignment: 512
step alignment: 8
base_object: *(double *) dv_44(D) + (sizetype) ((long unsigned int)
Q_35(D) * 8)
Access function 0: {0B, +, 8}_1
it's probably unfortunate association since we compute inside the loop
_11 = Q_35(D) + i_39;
_12 = (long unsigned int) _11;
_13 = _12 * 8;
With OpenMP SIMD we fail to analyze the data-refs:
Creating dr for D.4113[_37][1][0]
analyze_innermost: t.c:4:18: missed: failed: evolution of offset is not
affine.
base_address:
offset from base address:
constant offset from base address:
step:
base alignment: 0
base misalignment: 0
offset alignment: 0
step alignment: 0
base_object: D.4113
Access function 0: 0
Access function 1: 1
Access function 2: scev_not_known;
where _37 is the SIMD lane.
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53947
[Bug 53947] [meta-bug] vectorizer missed-optimizations
