[patch, doc] documenting new options

Diego Novillo dnovillo@google.com
Thu Dec 6 15:41:00 GMT 2007


On 12/06/07 09:14, Olga Golovanevsky wrote:
> This patch documents recently committed struct-reorg optimization,
> i.e. -fipa-struct-reorg option and struct-reorg-cold-struct-ratio
> parameter.
> 
> Any comments? Ok for mainline?
> 
> Olga
> 
> ChangeLog
> 
> 2007-12-06  Olga Golovanevsky  <olga@il.ibm.com>
> 
>       * doc/invoke.texi (Optimize Options): Document new -fipa-struct-reorg
>       option and struct-reorg-cold-struct-ratio parameter.
> 
> Index: invoke.texi
> ===================================================================
> --- invoke.texi   (revision 130578)
> +++ invoke.texi   (working copy)
> @@ -329,13 +329,13 @@ Objective-C and Objective-C++ Dialects}.
>  -fgcse-sm -fif-conversion -fif-conversion2 -finline-functions @gol
>  -finline-functions-called-once -finline-limit=@var{n} @gol
>  -finline-small-functions -fipa-pta -fipa-pure-const -fipa-reference @gol
> --fipa-type-escape -fivopts -fkeep-inline-functions -fkeep-static-consts
> @gol
> --fmerge-all-constants -fmerge-constants -fmodulo-sched @gol
> --fmodulo-sched-allow-regmoves -fmove-loop-invariants -fmudflap @gol
> --fmudflapir -fmudflapth -fno-branch-count-reg -fno-default-inline @gol
> --fno-defer-pop -fno-function-cse -fno-guess-branch-probability @gol
> --fno-inline -fno-math-errno -fno-peephole -fno-peephole2 @gol
> --fno-sched-interblock -fno-sched-spec -fno-signed-zeros @gol
> +-fipa-struct-reorg -fipa-type-escape -fivopts -fkeep-inline-functions @gol
> +-fkeep-static-consts -fmerge-all-constants -fmerge-constants @gol
> +-fmodulo-sched -fmodulo-sched-allow-regmoves -fmove-loop-invariants @gol
> +-fmudflap -fmudflapir -fmudflapth -fno-branch-count-reg @gol
> +-fno-default-inline -fno-defer-pop -fno-function-cse @gol
> +-fno-guess-branch-probability -fno-inline -fno-math-errno -fno-peephole
> @gol
> +-fno-peephole2 -fno-sched-interblock -fno-sched-spec -fno-signed-zeros
> @gol
>  -fno-toplevel-reorder -fno-trapping-math -fno-zero-initialized-in-bss @gol
>  -fomit-frame-pointer -foptimize-register-move -foptimize-sibling-calls
> @gol
>  -fpeel-loops -fpredictive-commoning -fprefetch-loop-arrays @gol
> @@ -5711,6 +5711,20 @@ Discover which static variables do not e
>  compilation unit.
>  Enabled by default at @option{-O} and higher.
> 
> +@item -fipa-struct-reorg
> +@opindex fipa-struct-reorg
> +Perform structure reorganization optimization, that change C-like
> structures
> +layout in order to better utilize spatial locality. Effective for programs

Two spaces after '.'.  This occurs in several places.
s/Effective for/This transformation is effective/

> +containing arrays of structures. Available in two compilation modes:
> +profile-based, as with @option{-fprofile-generate} and @option
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
profile-based (enabled with @option{-fprofile-generate})

> {-fprofile-use},
> +or static. Require @option{-fipa-type-escape} to provide the safety of
    ^^^^^^^^^
or static (which uses built-in heuristics).

> +transformations. Work as whole program optimization, i.e. require
> +@option{-fwhole-program} and @option{-combine} flags.

The transformation works only in whole program mode, so it requires 
@option{-fwhole-program} and @option{-combine} to be enabled.

> Cold structures
> +can remain intact through
> +@option{--param struct-reorg-cold-struct-ratio=@var{value}} option.

I'm not sure what you meant to say here.  Perhaps "Structures considered 
"cold" by the transformation are not affected (see @option{--param 
struct-reorg-cold-struct-ratio=@var{value}})."


> +
> +With this flag, the program debug info reflects a new structure layout.
> +
>  @item -fipa-pta
>  @opindex fipa-pta
>  Perform interprocedural pointer analysis.
> @@ -6624,6 +6638,13 @@ of bytes in instantiated fields to the n
>  structure exceeds this parameter, then block copies are not used.  The.
>  default is 75.
> 
> +@item struct-reorg-cold-struct-ratio
> +The threshold ratio between current and hotest structure counts

s/hotest/hottest/

> +used by @option{-fipa-struct-reorg}. We say that if the ratio of
> +the current structure count, calculated by profiling, to the hotest

What is "current structure count"?

s/hotest/hottest/

> +structure count in the program is less than this parameter, then
> +structure reorganization is not applied. The default is 10.
> +


Diego.



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