https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83008
--- Comment #33 from sergey.shalnov at intel dot com --- Richard, I'm not sure is it a regression or not. I see code has been visibly refactored in this commit https://github.com/gcc-mirror/gcc/commit/ee6e9ba576099aed29f1097195c649fc796ecf5e in 2013 year. However this fix is highly important for our workloads and really desirable for GCC8. For example, your patch plus SKX cost model changes give us ~+1% in geomean with spec2017 intrate. It would be really good for us to make this patch into GCC8. Cost model changes planned to be (will be proposed separately): diff --git a/gcc/config/i386/x86-tune-costs.h b/gcc/config/i386/x86-tune-costs.h index e943d13..d5e6ef6 100644 --- a/gcc/config/i386/x86-tune-costs.h +++ b/gcc/config/i386/x86-tune-costs.h @@ -1557,7 +1557,7 @@ struct processor_costs skylake_cost = { {4, 4, 4}, /* cost of loading integer registers in QImode, HImode and SImode. Relative to reg-reg move (2). */ - {6, 6, 6}, /* cost of storing integer registers */ + {6, 6, 3}, /* cost of storing integer registers */ 2, /* cost of reg,reg fld/fst */ {6, 6, 8}, /* cost of loading fp registers in SFmode, DFmode and XFmode */ @@ -1572,7 +1572,7 @@ struct processor_costs skylake_cost = { {6, 6, 6, 10, 20}, /* cost of loading SSE registers in 32,64,128,256 and 512-bit */ {6, 6, 6, 10, 20}, /* cost of unaligned loads. */ - {8, 8, 8, 8, 16}, /* cost of storing SSE registers + {8, 8, 8, 14, 24}, /* cost of storing SSE registers in 32,64,128,256 and 512-bit */ {8, 8, 8, 8, 16}, /* cost of unaligned stores. */ 2, 2, /* SSE->integer and integer->SSE moves */ I know that you have some concerns about costs above, I'm saving it for next discussion because your patch is a good foundation to proceed with costs tuning. Sergey
