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Path: utzoo!mnetor!uunet!husc6!necntc!ima!haddock!karl
From: karl@haddock.ISC.COM (Karl Heuer)
Newsgroups: comp.lang.c
Subject: Re: asm statements & the stack
Message-ID: <1339@haddock.ISC.COM>
Date: Wed, 7-Oct-87 19:28:34 EDT
Article-I.D.: haddock.1339
Posted: Wed Oct  7 19:28:34 1987
Date-Received: Sat, 10-Oct-87 16:36:42 EDT
References: <110@teletron.UUCP>
Reply-To: karl@haddock.ima.isc.com (Karl Heuer)
Organization: Interactive Systems, Boston
Lines: 17

In article <110@teletron.UUCP> andrew@teletron.UUCP (Andrew Scott) writes:
>[Tried to use the stack from an asm() instruction, and got bitten]

Well, in my opinion, the compiler is free to do whatever is easiest or most
efficient as long as it has the appropriate semantics.  If an asm() escape is
provided, it's the user's responsibility to know enough about the compiler to
avoid colliding with the generated code.

>The compiler I use ... allocates one more longword than necessary when
>creating foo's stack frame.

If this is a consistent feature, you could save %sr in that slot, and then
decrement the stack to make a new slot for the function to use.  Or, you could
avoid the stack entirely and store %sr in a static location, if you don't need
to nest the disable/enable calls.

Karl W. Z. Heuer (ima!haddock!karl or karl@haddock.isc.com), The Walking Lint