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From: kernel mailz <kernelmailz@googlemail.com>
To: gcc-help@gcc.gnu.org, gcc-help-help@gcc.gnu.org, linuxppc-dev@ozlabs.org
Subject: Inline Assembly queries
Date: Sun, 28 Jun 2009 01:16:56 +0530	[thread overview]
Message-ID: <abe8a1fd0906271246q920124ard61422d9577e2d09@mail.gmail.com> (raw)

Hello All the gurus,

I've been fiddling my luck with gcc 4.3.2 inline assembly on powerpc
There are a few queries

1. asm volatile or simply asm produce the same assembly code.
Tried with a few examples but didnt find any difference by adding
volatile with asm

2. Use of "memory" and clobbered registers.

"memory" -
a. announce to the compiler that the memory has been modified
b. this instruction writes to some memory (other than a listed output)
and GCC shouldn=92t cache memory values in registers across this asm.

I tried with stw and stwcx instruction, adding "memory" has no effect.

Is there any example scenerio where gcc would generate different
assembly by adding / removing "memory" ?


-TZ

             reply	other threads:[~2009-06-27 19:47 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-06-27 19:46 kernel mailz [this message]
     [not found] ` <abe8a1fd0906271249k479e5a87gfe1ee9c02798a234@mail.gmail.com>
     [not found]   ` <m3ab3t4623.fsf@google.com>
2009-06-28  4:57     ` Inline Assembly queries kernel mailz
2009-06-29 15:49       ` kernel mailz
2009-06-29 19:27         ` Scott Wood
2009-06-30  5:27           ` kernel mailz
2009-06-30 10:41             ` Benjamin Herrenschmidt
2009-06-29 21:29         ` Ian Lance Taylor
2009-06-30  5:53           ` kernel mailz
2009-06-30  9:30             ` Andrew Haley
2009-06-30  9:52             ` Paul Mackerras
2009-06-29 15:57       ` David Howells
2009-06-29 21:27         ` Ian Lance Taylor
2009-06-30 10:43         ` Benjamin Herrenschmidt

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