This is the mail archive of the
gcc-bugs@gcc.gnu.org
mailing list for the GCC project.
[Bug target/64909] [4.8/4.9/5 Regression] Missed vectorization with bdver1
- From: "rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Tue, 10 Feb 2015 08:50:31 +0000
- Subject: [Bug target/64909] [4.8/4.9/5 Regression] Missed vectorization with bdver1
- Auto-submitted: auto-generated
- References: <bug-64909-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64909
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target| |x86_64-*-*, i?86-*-*
Priority|P3 |P2
Status|WAITING |NEW
Component|middle-end |target
Known to work| |4.7.4
Target Milestone|6.0 |4.8.5
Summary|Missed vectorization |[4.8/4.9/5 Regression]
| |Missed vectorization with
| |bdver1
Known to fail| |4.8.3, 4.9.2, 5.0
--- Comment #9 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed with -march=bdver1. A cost model issue:
t.c:6:3: note: Cost model analysis:
Vector inside of loop cost: 24
Vector prologue cost: 0
Vector epilogue cost: 336
Scalar iteration cost: 14
Scalar outside cost: 0
Vector outside cost: 336
prologue iterations: 0
epilogue iterations: 4
Calculated minimum iters for profitability: 30
t.c:6:3: note: Runtime profitability threshold = 29
t.c:6:3: note: Static estimate profitability threshold = 29
t.c:6:3: note: not vectorized: vectorization not profitable.
the vector epilogue cost looks odd to me. Without -march=bdver1 I get 12.