https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78261
Bug ID: 78261
Summary: vect pass only vectorizes half of the array in
gcc.c-torture/execute/pr68532.c
Product: gcc
Version: 7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: acsawdey at gcc dot gnu.org
CC: rguenth at gcc dot gnu.org, wschmidt at gcc dot gnu.org
Target Milestone: ---
Target: powerpc64*-*-*
Created attachment 39995
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=39995&action=edit
asm output
In this test case the loop in test() is vectorized but for some reason we only
end up generating vector code to do half of the array and a small loop to do
the other half.
Compile options:
xgcc gcc/testsuite/gcc.c-torture/execute/pr68532.c -mcpu=power8
-fno-diagnostics-show-caret -fdiagnostics-color=never -O2 -O2 -ftree-vectorize
-fno-vect-cost-model -lm -fdump-tree-all-all -S -o pr68532_p8.s
The vect pass appears to know what is going on from this output:
vectorization_factor = 8, niters = 16
However it only ends up generating 8 iterations with of vector code and then a
serial loop that runs for 8 iterations to finish up the computation:
li 9,8
addi 4,4,128
mtctr 9
[...]
.L2:
lhz 9,0(4)
addi 4,4,16
mullw 9,9,5
add 3,9,3
rlwinm 3,3,0,0xffff
bdnz .L2
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