https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69297
Bug ID: 69297
Summary: [6 Regression] Performance regression after r230020
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: ysrumyan at gmail dot com
Target Milestone: ---
This regression was found on spec2006/464.h264ref. The problem is related to
SLP vectorization of BB's and caused by the wrong calculation of scalar cost,
e.g. for attached test-case:
Cost model analysis:
Vector inside of basic block cost: 188
Vector prologue cost: 0
Vector epilogue cost: 0
Scalar cost of basic block: 512
although the basic block contains only 96 statements.
I found out that vect_bb_slp_scalar_cost takes into account the same stmt
several times and results in non-profitable SLP vectorization.
