Re: Symbol table 14/many: cleanups of cgraphunit.c

[Steven Bosscher <stevenb dot gcc at gmail dot com>]

Hello,

Thanks for this work!

Below are a bunch of spelling fixes ;-)


On Wed, Apr 25, 2012 at 6:32 PM, Jan Hubicka <hubicka@ucw.cz> wrote:
> --- 19,28 ----
> ?along with GCC; see the file COPYING3. ?If not see
> ?<http://www.gnu.org/licenses/>. ?*/
>
> ! /* This module implements main driver of compilation process.

"This module implements the main driver of the compilation process."

> ? ? The main scope of this file is to act as an interface in between
> ! ? ?tree based frontends and the backend.

s/tree based/GENERIC based/, or leave the 'tree' bit out (is there
another kind of front end?).

s/frontend/front end/g
s/backend/back end/g


> ? ? The front-end is supposed to use following functionality:

s/front-end/front end/

> ? ? ? ?The function can be called multiple times when multiple source level
> ! ? ? ? compilation units are combined.

Is this still applicable? I thought -combine was removed. Or is this
for things like Fortran modules?


> ? ? ?- cgraph_optimize
>
> ! ? ? ? This passes control to the back-end. ?Optimizations are performed and

s/back-end/back end/

> ! ? ? ? final assembler is generated. ?This is done in the following way. Note
> ! ? ? ? that with link time optimization the process is split into three
> ! ? ? ? stages (compile time, linktime analysis and parallel linktime as

s/linktime/link time/g

> ! ? ? ? indicated bellow).
> !
> ! ? ? ? Compile time:
> !
> ! ? ? ? 1) Inter-procedural optimization.
> ! ? ? ? ? ?(ipa_passes)
> !
> ! ? ? ? ? ?This part is further split into:
> !
> ! ? ? ? ? ?a) early optimizations. These are local passes executed in
> ! ? ? ? ? ? ? the topological order on the callgraph.
> !
> ! ? ? ? ? ? ? The purpose of early optimiations is to optimize away simple
> ! ? ? ? ? ? ? things that may otherwise confuse IP analysis. Very simple
> ! ? ? ? ? ? ? propagation across the callgraph is done i.e. to discover

s/i.e./e.g./

> ! ? ? ? ? ? ? functions without side effects and simple inlining is performed.
> !
> ! ? ? ? ? ?b) early small interprocedural passes.
> !
> ! ? ? ? ? ? ? Those are interprocedural passes executed only at compilation
> ! ? ? ? ? ? ? time. ?These include, for exmaple, transational memory lowering,

s/exmaple/example/

> ! ? ? ? ? ? ? unreachable code removal and other simple transformations.
> !
> ! ? ? ? ? ?c) IP analysis stage. ?All interprocedural passes do their
> ! ? ? ? ? ? ? analysis.
> !
> ! ? ? ? ? ? ? Interprocedural passes differ from small interprocedural
> ! ? ? ? ? ? ? passes by their ability to operate across whole program

s/whole program/the whole program/, or "a whole program", or "whole programs".

> ! ? ? ? ? ? ? at linktime. ?Their analysis stage is performed early to
> ! ? ? ? ? ? ? both reduce linking times and linktime memory usage by
> ! ? ? ? ? ? ? not having to represent whole program in memory.
> !
> ! ? ? ? ? ?d) LTO sreaming. ?When doing LTO, everything important gets

s/sreaming/streaming/

> ! ? ? ? ? ? ? streamed into the object file.
> !
> ! ? ? ? ?Compile time and or linktime analysis stage (WPA):
> !
> ! ? ? ? ? ? ? At linktime units gets streamed back and symbol table is

s/units gets/units get/
s/and symbol/and the symbol/

> ! ? ? ? ? ? ? merged. ?Function bodies are not streamed in and not
> ! ? ? ? ? ? ? available.
> ! ? ? ? ? ?e) IP propagation stage. ?All IP passes execute their
> ! ? ? ? ? ? ? IP propagation. This is done based on the earlier analysis
> ! ? ? ? ? ? ? without having function bodies at hand.
> ! ? ? ? ? ?f) Ltrans streaming. ?When doing WHOPR LTO, the program
> ! ? ? ? ? ? ? is partitioned and streamed into multple object files.

s/multple/multiple/

> !
> ! ? ? ? ?Compile time and/or parallel linktime stage (ltrans)
>
> + ? ? ? ? ? ? Each of the object files is streamed back and compiled
> + ? ? ? ? ? ? separately. ?Now the function bodies becomes available
> + ? ? ? ? ? ? again.
> +
> + ? ? ? ?2) Virtual clone materialization
> + ? ? ? ? ? (cgraph_materialize_clone)
> +
> + ? ? ? ? ? IP passes can produce copies of existing functoins (such

s/functoins/functions/

> + ? ? ? ? ? as versioned clones or inline clones) without actually
> + ? ? ? ? ? manipulating their bodies by creating virtual clones in
> + ? ? ? ? ? the callgraph. At this time the virtual clones are
> + ? ? ? ? ? turned into real functions

add newline

> + ? ? ? ?3) IP transformation
> +
> + ? ? ? ? ? All IP passes transform function bodies based on earlier
> + ? ? ? ? ? decision of the IP propagation.
> +
> + ? ? ? ?4) late small IP passes
> +
> + ? ? ? ? ? Simple IP passes working within single program partition.
> +
> + ? ? ? ?5) Expansion
> + ? ? ? ? ? (cgraph_expand_all_functions)
> +
> + ? ? ? ? ? At this stage functions that needs to be output into

s/needs/need/

> + ? ? ? ? ? assembler are identified and compiled in topological order

s/order/order./
add newline

> + ? ? ? ?6) Output of variables and aliases
> + ? ? ? ? ? Now it is known what variable references was not optimized

s/references was not/references were not/

> + ? ? ? ? ? out and thus all variables are output to the file.
> +
> + ? ? ? ? ? Note that with -fno-toplevel-reorder passes 5 and 6
> + ? ? ? ? ? are combined together in cgraph_output_in_order.
> +
> + ? ?Finally there are functions to manipulate the callgraph from

s/from/from the/

> + ? ?backend.
> + ? ? - cgraph_add_new_function is used to add backend produced

s/backend/back-end/

> + ? ? ? functions introduced after the unit is finalized.
> + ? ? ? The functions are enqueue for later processing and inserted
> + ? ? ? into callgraph with cgraph_process_new_functions.

s/into/into the/

> +
> + ? ? - cgraph_function_versioning
> +
> + ? ? ? produces a copy of function into new one (a version)
> + ? ? ? and apply simple transformations

s/apply/applies/ or s/produces/produce/


Ciao!
Steven