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.