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Date: Tue, 21 Apr 2015 15:34:47 +0900
From: Namhyung Kim <namhyung@kernel.org>
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>, Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Jiri Olsa <jolsa@redhat.com>, LKML <linux-kernel@vger.kernel.org>,
        David Ahern <dsahern@gmail.com>
Subject: Re: [PATCH 3/7] perf tools: Move TUI-specific fields to struct
 hist_entry_tui
Message-ID: <20150421063447.GD1905@sejong>
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 <20150420194411.GI11111@kernel.org>
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On Mon, Apr 20, 2015 at 04:44:11PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Mon, Apr 20, 2015 at 10:00:46PM +0900, Namhyung Kim escreveu:
> > +++ b/tools/perf/ui/browsers/hists.c
> > @@ -61,7 +61,7 @@ static int hist_browser__get_folding(struct hist_browser *browser)
> >  			rb_entry(nd, struct hist_entry, rb_node);
>   
> >  		if (he->ms.unfolded)
> > -			unfolded_rows += he->nr_rows;
> > +			unfolded_rows += he->tui.nr_rows;
> 
> To avoid all these changes, I wonder if we can't use unamed structs in
> addition to the unnamed union?

But diff code uses named struct.  Does it support a mixed union
including named and unnamed members?

Hmm.. looks like it is.

#include <stdbool.h>
#include <stdio.h>

struct hist_entry {
	union {
		struct /* tui */ {
			int nr_rows;
			int row_offset;
			/* other fields */
		};
		struct /* diff */ {
			bool computed;
			/* other fields */
		} diff;
	};
};

int main(int argc, char *argv[])
{
	struct hist_entry he = { .nr_rows = 11, .row_offset = 19, };
	
	printf("he.nr_rows=%d, he.row_offset=%d, he.diff.computed=%d\n",
		he.nr_rows, he.row_offset, he.diff.computed);
}

namhyung@sejong:tmp$ make mixed
cc     mixed.c   -o mixed
namhyung@sejong:tmp$ ./mixed
he.nr_rows=11, he.row_offset=19, he.diff.computed=11


OK, I'll change it to unnamed struct.

Thanks,
Namhyung


> 
> Like this what is done in include/net/sock.h, struct sock_common, and
> here:
> 
> [root@zoo ~]# cat unnamed_struct_union.c 
> #include <stdbool.h>
> #include <stdio.h>
> 
> struct hist_entry {
> 	union {
> 		struct /* tui */ {
> 			int nr_rows;
> 			int row_offset;
> 			/* other fields */
> 		};
> 		struct /* diff */ {
> 			bool computed;
> 			/* other fields */
> 		};
> 	};
> };
> 
> int main(int argc, char *argv[])
> {
> 	struct hist_entry he = { .nr_rows = 11, .row_offset = 19, };
> 	
> 	printf("he.nr_rows=%d, he.row_offset=%d\n", he.nr_rows,
> he.row_offset);
> }
> [root@zoo ~]# make unnamed_struct_union
> cc     unnamed_struct_union.c   -o unnamed_struct_union
> [root@zoo ~]# ./unnamed_struct_union 
> he.nr_rows=11, he.row_offset=19
> [root@zoo ~]#
> 
> - Arnaldo
> --
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