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Date: Fri, 14 Mar 2003 20:10:00 -0000
Subject: Re: store double-cvtd-to-int to memory
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Cc: Dale Johannesen <dalej@apple.com>, David Edelsohn <dje@watson.ibm.com>,
   Richard Henderson <rth@redhat.com>, gcc@gcc.gnu.org
To: Geoff Keating <geoffk@geoffk.org>
From: Dale Johannesen <dalej@apple.com>
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On Friday, March 14, 2003, at 11:37  AM, Geoff Keating wrote:
> David Edelsohn <dje@watson.ibm.com> writes:
>
>> 	Can't you just mark the unnecessary temp with "X" constraint for
>> the pattern that does not need it?
>
> That would be a good idea, but doesn't solve Dale's problem...

Right.  The problem is not that the pattern isn't recognized, it's
that combine won't consider it in the first place.
(I did run this by Geoff before asking the list, btw, which
makes me think it's not a case of me missing something trivial.)
Basically I'm trying to get combine to merge these 2 patterns:

(insn 11 10 12 0 0x0 (set (mem:SI (reg:SI 5 r5) [0 S4 A32])
         (reg:SI 120)) 309 {*movsi_internal1} (insn_list 10 (nil))

(insn 10 5 11 0 0x0 (parallel [
             (set (reg:SI 120)
                 (fix:SI (reg:DF 33 f1)))
             (clobber (reg:DI 121))
             (clobber (mem/f:DI (plus:SI (reg/f:SI 30 r30)
                         (const_int 32 [0x20])) [0 S8 A64]))

It considers generating
(insn 10 5 11 0 0x0 (parallel [
             (set (mem:SI (reg:SI 5 r5)
                 (fix:SI (reg:DF 33 f1)))
             (clobber (reg:DI 121))
             (clobber (mem/f:DI (plus:SI (reg/f:SI 30 r30)
                         (const_int 32 [0x20])) [0 S8 A64]))
and rejects that because it thinks the mem's might conflict, as I said 
before.
It also considers generating
             (set (mem:SI (reg:SI 5 r5)
                 (fix:SI (reg:DF 33 f1)))
which isn't adequate because I *do* need the floating point scratch reg.
It does not consider generating
(insn 10 5 11 0 0x0 (parallel [
             (set (mem:SI (reg:SI 5 r5)
                 (fix:SI (reg:DF 33 f1)))
             (clobber (reg:DI 121))]
which is what I want.
(Not that it has anything to do with this problem, but why is the 
scratch
reg DI not DF?)