From: Jim Wilson <wilson@specifixinc.com>
To: "Sruthy C.N" <csy2p100@nitc.ac.in>
Cc: gcc@gcc.gnu.org
Subject: Re: RTL
Date: Thu, 25 Sep 2003 05:02:00 -0000 [thread overview]
Message-ID: <3F727452.5090402@specifixinc.com> (raw)
In-Reply-To: <2734.210.212.228.78.1064463025.webmail@ebox.nitc.ac.in>
Sruthy C.N wrote:
> In the RTL file (gcc version 3.2.2) there is some instructions(insn
> 6,8,10,12) which do some manipulations on esp..what is it doing?
As I mentioned in a previous message, it is aligning the stack in main
to a 16 byte boundary. I believe this is for the MMX/SSE/SSE2
instructions, which are faster if the stack is 16 byte aligned. Some
systems don't align the stack to 16 bytes at program startup, so we do
it in main. This extra instruction only occurs in the main function.
> If we consider the assembly program corresponding to this there is
> no such instructions corresponding to this..why?
Please give a testcase. I suspect you got your examples mixed up. Or
maybe it got optimized away, though that seems unlikely.
--
Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com
next prev parent reply other threads:[~2003-09-25 4:51 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-09-25 4:37 RTL Sruthy C.N
2003-09-25 4:38 ` RTL Sruthy C.N
2003-09-25 5:02 ` Jim Wilson [this message]
2003-09-30 12:45 ` RTL Sruthy C.N
2003-10-06 23:27 ` RTL Jim Wilson
2003-09-30 13:12 ` RTL Sruthy C.N
-- strict thread matches above, loose matches on Subject: below --
2003-08-29 14:24 RTL SRUTHY C.N.
2003-08-29 14:41 ` RTL SRUTHY C.N.
2003-08-27 17:47 RTL SRUTHY C.N.
2003-08-27 18:08 ` RTL SRUTHY C.N.
2003-08-28 0:47 ` RTL Jim Wilson
2002-10-04 1:36 rtl N V Krishna
2002-10-04 7:07 ` rtl Shekhar Divekar
2002-10-04 12:00 ` rtl Mike Stump
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