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From: Steve Ellcey <sellcey@cavium.com>
To: gcc@gcc.gnu.org
Subject: Question about -fopt-info output (-fopt-info vs. -fopt-info-all)
Date: Tue, 02 May 2017 21:40:00 -0000	[thread overview]
Message-ID: <201705022140.v42LePNH012760@sellcey-dt.caveonetworks.com> (raw)

I have a question about -fopt-info.  According to the GCC documentation at:

  https://gcc.gnu.org/onlinedocs/gccint/Dump-examples.html


| If options is omitted, it defaults to all-all, which means dump all 
| available optimization info from all the passes. In the following example,
| all optimization info is output on to stderr.
|
|   gcc -O3 -fopt-info

But when I use the '-fopt-info' flag, I get less output about vectorization
than when I use '-fopt-info-all' or '-fopt-info-all-all'.

For example if I compile:

	int foo(int *a, int *b, int *c, int n) {
		int i;
		for (i = 0; i < n; i++)
			a[i] = b[i] + c[i];
	}

with '-O3 -fopt-info' I get 6 lines of output.  '-O3 -fopt-info-all'
or '-O3 -fopt-info-all-all' gives me 453 lines of output.

Is the documentation wrong, the implementation wrong, or my understanding
of what the documentation is saying wrong?

Steve Ellcey
sellcey@cavium.com

             reply	other threads:[~2017-05-02 21:40 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-02 21:40 Steve Ellcey [this message]
2017-05-03  9:51 ` Richard Biener

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