lkml.org 
[lkml]   [2017]   [Mar]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] objtool: drop redundant flags generation
On Mon,  6 Mar 2017 18:00:25 +0100
Nicholas Mc Guire <der.herr@hofr.at> wrote:

> The generator was emitting quite a few duplicate flags which was making
> doublebitand.cocci nervous. This awk hack resolves the duplicate issue.

Yes, I know that.
I don't think that the duplicating those flags in "automatic generated"
source code is not so harmful. I personally prefer to keep awk code
simpler...

Thanks,

>
> Signed-off-by: Nicholas Mc Guire <der.herr@hofr.at>
> ---
>
> The coccinelle complaints emitted was about 230 findings total:
> ./arch/x86/lib/inat-tables.c:214:10-20: duplicated argument to & or |
> ./arch/x86/lib/inat-tables.c:214:23-33: duplicated argument to & or |
> ./arch/x86/lib/inat-tables.c:218:10-20: duplicated argument to & or |
> ./arch/x86/lib/inat-tables.c:218:23-33: duplicated argument to & or |
> ....
> ./tools/objtool/arch/x86/insn/inat-tables.c:214:10-20: duplicated argument to & or |
> ./tools/objtool/arch/x86/insn/inat-tables.c:214:23-33: duplicated argument to & or |
> ./tools/objtool/arch/x86/insn/inat-tables.c:218:10-20: duplicated argument to & or |
> ./tools/objtool/arch/x86/insn/inat-tables.c:218:23-33: duplicated argument to & or |
> ...
> spatch --sp-file scripts/coccinelle/tests/doublebitand.cocci inat-tables.c -D report
> will give you the full list - all are caused by duplicates in the generated
> output by the add_flags function in the two instances of gen-insn-attr-x86.awk.
>
> Q: The two copies of gen-insn-attr-x86.awk are identical and its not actually clear
> why this duplication is needed ? Further the maintainers list emitted for the
> two files differ.
>
> Patch was checked by manual review of the diff between the initial file and the
> regenerated file after the below patch was applied.
> Second verification was by make tools/objtool and comparing the generated binaries
> in tools/objtool/arch/x86/decode.o with diff.
>
> Patch is against 4.11-rc1 (localversion-next is next-20170306)
>
> arch/x86/tools/gen-insn-attr-x86.awk | 12 ++++++++++--
> tools/objtool/arch/x86/insn/gen-insn-attr-x86.awk | 12 ++++++++++--
> 2 files changed, 20 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/tools/gen-insn-attr-x86.awk b/arch/x86/tools/gen-insn-attr-x86.awk
> index a3d2c62..9cdeefe 100644
> --- a/arch/x86/tools/gen-insn-attr-x86.awk
> +++ b/arch/x86/tools/gen-insn-attr-x86.awk
> @@ -226,8 +226,16 @@ function print_table(tbl,name,fmt,n)
> }
>
> function add_flags(old,new) {
> - if (old && new)
> - return old " | " new
> + if (old == new)
> + return old
> + if (old && new) {
> + if(match(old,new))
> + return old
> + else if(match(new,old))
> + return new
> + else
> + return old " | " new
> + }
> else if (old)
> return old
> else
> diff --git a/tools/objtool/arch/x86/insn/gen-insn-attr-x86.awk b/tools/objtool/arch/x86/insn/gen-insn-attr-x86.awk
> index a3d2c62..9cdeefe 100644
> --- a/tools/objtool/arch/x86/insn/gen-insn-attr-x86.awk
> +++ b/tools/objtool/arch/x86/insn/gen-insn-attr-x86.awk
> @@ -226,8 +226,16 @@ function print_table(tbl,name,fmt,n)
> }
>
> function add_flags(old,new) {
> - if (old && new)
> - return old " | " new
> + if (old == new)
> + return old
> + if (old && new) {
> + if(match(old,new))
> + return old
> + else if(match(new,old))
> + return new
> + else
> + return old " | " new
> + }
> else if (old)
> return old
> else
> --
> 2.1.4
>


--
Masami Hiramatsu <mhiramat@kernel.org>

\
 
 \ /
  Last update: 2017-03-07 09:17    [W:0.407 / U:0.732 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site