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Re: [patch] MIPS/gcc: Revert removal of DImode shifts for 32-bit targets

To: Richard Sandiford <>
Subject: Re: [patch] MIPS/gcc: Revert removal of DImode shifts for 32-bit targets
From: Nigel Stephens <>
Date: Tue, 03 Aug 2004 10:22:44 +0100
Cc: "Maciej W. Rozycki" <>, Ralf Baechle <>, Richard Henderson <>,,
In-reply-to: <>
Organization: MIPS Technologies
Original-recipient: rfc822;
References: <> <> <> <> <> <> <> <> <> <>
User-agent: Mozilla Thunderbird 0.5 (Windows/20040207)

Richard Sandiford wrote:

Nigel Stephens <> writes:
I have a patch against gcc-3.4 <snip>
If people really don't like the inline expansion, then maybe it could be
enabled or disabled by a new -m option.

IMO, controlling with optimize_size would be enough.

Yes, that sounds right.

But it sounds from
your description like the patch just adds a new hard-coded multi-insn
asm string.  Is that right?  If so, I'd really like to avoid that.

Yes, and I totally agree with you.

It would much better IMO if we handle this in the target-independent
parts of the compiler.  We can already open-code certain non-native
operations, it's "just" that wide shifts are a missing case.

If we handle it in a target-independent way, with each insn exposed
separately, we will be able to optimize special cases better.
We'll also get the usual scheduling benefits.

I agree that we should open-code it for the obvious reasons, but does it have to be target independent, or could/should we prototype it with define_expand?


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