From: "Zvilius, Mark" <Mark.Zvilius@fluke.com>
To: "'gcc-help@gcc.gnu.org'" <gcc-help@gcc.gnu.org>
Subject: asm constraints
Date: Fri, 27 Aug 2004 06:58:00 -0000 [thread overview]
Message-ID: <732BE51FE9901143AE04411A11CC46560484AAB5@evtexc02.tc.fluke.com> (raw)
For a PowerPC architecture I'm using the following asm statement in C source
to read a time base register:
unsigned int tbl;
__asm__("mftbl %0" : "=r" (tbl));
The code this generates is:
mftb r0
mr r9,r0
stw r9,0x18(r31)
I'm wondering why it's wasting a register. Am I specifying the constraint
incorrectly?
Mark Z.
next reply other threads:[~2004-08-26 22:17 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-08-27 6:58 Zvilius, Mark [this message]
2004-08-27 11:16 ` Segher Boessenkool
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