From: Ian Lance Taylor <iant@google.com>
To: Hariharan Sandanagobalane <hariharans@picochip.com>
Cc: gcc@gcc.gnu.org
Subject: Re: Stack parameter - pass by value - frame usage
Date: Thu, 13 Sep 2007 20:41:00 -0000 [thread overview]
Message-ID: <m37imu2t9c.fsf@localhost.localdomain> (raw)
In-Reply-To: <46E92357.5070502@picochip.com>
Hariharan Sandanagobalane <hariharans@picochip.com> writes:
> I looked at an inefficient code sequence for a simple program using
> GCC's picochip port (not yet submitted to mainline).
Are you working with mainline sources?
> Note that the parameter is being written to the frame in the last 2
> instructions above. This, i am guessing is the reason for the
> get_frame_size() returning 4 later on, though the actual save of the
> struct parameter value on the stack is being eliminated at later
> optimization phases (CSE and DCE, i believe).
>
> Why does the compiler do this? I vaguely remember x86 storing all
> parameter values on stack. Is that the reason for this behaviour? Is
> there anything i can do in the port to get around this problem?
At a guess, it's because the frontend decided that the struct was
addressable and needed to be pushed on the stack. I thought this got
cleaned up recently, though.
Ian
next prev parent reply other threads:[~2007-09-13 20:41 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-13 11:47 Hariharan Sandanagobalane
2007-09-13 20:41 ` Ian Lance Taylor [this message]
2007-09-21 10:42 ` Hariharan Sandanagobalane
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