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Re: [PATCH] Fix PR opt/5172: Store motion vs. asm_operands
- From: Richard Henderson <rth at redhat dot com>
- To: Roger Sayle <roger at eyesopen dot com>
- Cc: gcc-patches at gcc dot gnu dot org, Andreas Jaeger <aj at suse dot de>
- Date: Tue, 22 Jan 2002 13:40:08 -0800
- Subject: Re: [PATCH] Fix PR opt/5172: Store motion vs. asm_operands
- References: <Pine.LNX.4.33.0201160031160.21255-100000@www.eyesopen.com>
On Wed, Jan 16, 2002 at 01:05:49AM -0700, Roger Sayle wrote:
> My understanding is that both volatile and non-volatile asm statements
> may legitimately read from anywhere in memory (and that volatile reflects
> the asm's ability to write to, not read from, memory).
Incorrect. No asm statement may implicitly read or write memory.
One must represent memory inputs, outputs, and clobbers properly.
Note that the easiest way to do this is with "memory" in the
clobber section of the extended asm statement.
r~