From: "Paul Edwards" <mutazilah@gmail.com>
To: "Ulrich Weigand" <uweigand@de.ibm.com>
Cc: "Joseph S. Myers" <joseph@codesourcery.com>, <gcc@gcc.gnu.org>
Subject: Re: i370 port
Date: Thu, 17 Sep 2009 13:00:00 -0000 [thread overview]
Message-ID: <89EAA39DC259473589AC0E907390A6E5@Paullaptop> (raw)
In-Reply-To: <200909151350.n8FDownl009821@d12av02.megacenter.de.ibm.com>
Hi Ulrich.
Good news is that I have now gotten GCC 3.4.6 to recompile
itself with full optimization on. The compilation time on the
(emulated) mainframe is only 2.5 hours as only a single pass
is required. GCC 3.4.6 requires 49 MB to recompile c-common!
I assume with GCC 3.4.6 it is doing global optimization or
something. It was only 20 MB under 3.2.3.
Anyway, I'm still continuing the cleanup, but now have a strong
fallback position. Basically I won't introduce any machine
definition change that causes the self-compile to fail.
>> ;(define_insn ""
>> ; [(set (match_operand:SI 0 "register_operand" "=d")
>> ; (mult:SI (match_operand:SI 1 "register_operand" "0")
>> ; (match_operand:SI 2 "immediate_operand" "K")))]
>> ; ""
>> ; "*
>> ;{
>> ; check_label_emit ();
>> ; mvs_check_page (0, 4, 0);
>> ; return \"MH %0,%H2\";
>> ;}"
>> ; [(set_attr "length" "4")]
>> ;)
>
> The combination of predicates and constraints on this insn is broken.
>
> Before reload, the predicate "immediate_operand" explicitly allows
> *any* SImode immediate value. However, during reload, the "K"
> constraint accepts only a subset of values.
Is there a way to give a predicate that just says "look at the
constraint"? It seems a bit overkill to add a new predicate
for this one instruction.
> As there is no other alternative,
No other alternative for this same pattern, right? There was an
alternative - the pattern that I explictly asked it to use, since
I'd already done the K check in advance.
> and the insn supports neither memory nor register
> operands, this is impossible for reload to fix up.
Hmmm. I was wondering whether I could put a memory operand
there, if that means it can fix it up regardless. But that would
give it the idea that it can put a fullword there, when a halfword
operand is required, right?
> In addition, I don't quite understand how this pattern works in
> the first place; MH requires a memory operand, but this pattern
> seems to output an immediate value as operand. Is there some
> magic going on in your assembler?
%H2 is ...
;; Special formats used for outputting 370 instructions.
;;
;; %H -- Print a signed 16-bit constant.
in the i370.md documentation which can be seen here:
http://gcc.gnu.org/viewcvs/trunk/gcc/config/i370/i370.md?revision=71850&view=markup&pathrev=77215
(there's not a lot of technical changes since then, mainly
because no-one knew how to make them).
> If you indeed want to output immediate values here, you should
As opposed to wanting what? All I want is the MH instruction
to be available for use, so that when someone writes x = x * 5,
it doesn't have to organize a register pair.
> probably define a new *predicate* that constrains the set of
> allowed values even before reload.
Ok, that should be straightforward if that's the best solution.
> In the s390 port, we're instead modelling the MH instruction
> with a memory operand (this still allows the generic parts of
> GCC to push immediate operands into memory, if they are in
> range for an HImode operand):
>
> (define_insn "*mulsi3_sign"
> [(set (match_operand:SI 0 "register_operand" "=d")
> (mult:SI (sign_extend:SI (match_operand:HI 2 "memory_operand" "R"))
> (match_operand:SI 1 "register_operand" "0")))]
> ""
> "mh\t%0,%2"
> [(set_attr "op_type" "RX")
> (set_attr "type" "imul")])
I tried a lot of variations to try to get this to fit into the i370
scheme, but didn't have any luck.
e.g. I managed to make this:
(define_insn ""
[(set (match_operand:SI 0 "register_operand" "=d")
(mult:SI (sign_extend:SI (match_operand:HI 2 "memory_operand" "g"))
(match_operand:SI 1 "register_operand" "0")))]
""
"*
{
check_label_emit ();
mvs_check_page (0, 4, 0);
return \"MH^I%0,%2\";
}"
[(set_attr "length" "4")]
)
produce:
C:\devel\gccnew\gcc>gccmvs -DUSE_MEMMGR -Os -S -ansi -pedantic-errors -DHAVE_CON
FIG_H -DIN_GCC -DPUREISO -I ../../pdos/pdpclib -I . -I config/i370 -I
../include
cfgloopanal.c
cfgloopanal.c: In function `average_num_loop_insns':
cfgloopanal.c:1379: error: unrecognizable insn:
(insn 68 67 71 7 (set (reg:SI 45)
(mult:SI (reg:SI 44 [ <variable>.frequency ])
(const_int 10000 [0x2710]))) -1 (insn_list 67 (nil))
(expr_list:REG_DEAD (reg:SI 44 [ <variable>.frequency ])
(nil)))
> This also seems broken. A MULT:DI must have two DImode operands,
> it cannot have one DImode and one SImode operand. Also, it is in
> fact incorrect that it takes the full DImode first operand; rather,
> it only uses the low 32-bit of its first operand as input.
Ok.
> In the s390 port we're modelling the real behavior of the instruction
> using two explicit SIGN_EXTEND codes:
>
> (define_insn "mulsidi3"
> [(set (match_operand:DI 0 "register_operand" "=d,d")
> (mult:DI (sign_extend:DI
> (match_operand:SI 1 "register_operand" "%0,0"))
> (sign_extend:DI
> (match_operand:SI 2 "nonimmediate_operand" "d,R"))))]
Ok. That certainly looks better.
> Well, the point of optimization is that the RTXes do not stay the
> way they were originally expanded ... The optimizers will attempt
> to perform various generic optimization on the code, and if the
> back-end claims to support a pattern that implements any of those
> optimized forms, it will get used. In this case, even though you
> expanded a DImode multiply, common code may notice that it can
> be optimized to a SImode multiply instead.
>
> Generally speaking, your RTX patterns *must* be fully correct and
> represent the actual behavior of the machine in all cases. If there
> are corner cases formally allowed by the RTX pattern, but the
> behavior of the machine differs, this may cause breakage. Even if
> your expanders avoid those corner cases when using your patterns,
> this will not be true for the optimizers.
Ok. It seems the proper way to go, but given that I don't know
how to integrate that into the existing code, it's probably better
for me to go with the new predicate, which I can very likely get
to work.
BFN. Paul.
next prev parent reply other threads:[~2009-09-17 13:00 UTC|newest]
Thread overview: 162+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-09 22:33 Paul Edwards
2009-09-14 15:42 ` Ulrich Weigand
2009-09-15 12:59 ` Paul Edwards
2009-09-15 13:51 ` Ulrich Weigand
2009-09-17 13:00 ` Paul Edwards [this message]
2009-09-17 17:55 ` Ulrich Weigand
2009-09-18 0:35 ` Paul Edwards
2009-09-18 12:06 ` Ulrich Weigand
2009-09-18 12:23 ` Paul Edwards
2009-09-18 13:27 ` Ulrich Weigand
2009-09-18 13:42 ` Paul Edwards
2009-09-18 16:08 ` Ulrich Weigand
2009-09-19 12:57 ` Paul Edwards
2009-09-25 10:19 ` Paul Edwards
2009-09-25 15:20 ` Ulrich Weigand
2009-09-30 17:24 ` i370 port - constructing compile script Paul Edwards
2009-09-30 17:36 ` Richard Henderson
2009-09-30 21:40 ` Paul Edwards
[not found] ` <mcrpr98x9w8.fsf@dhcp-172-17-9-151.mtv.corp.google.com>
2009-10-01 0:16 ` Joseph S. Myers
2009-10-01 14:00 ` Paul Edwards
2009-10-02 12:41 ` Paul Edwards
2009-10-02 16:00 ` Ian Lance Taylor
2009-10-02 22:53 ` Paul Edwards
2009-10-04 4:11 ` Ian Lance Taylor
2009-10-04 5:14 ` Paul Edwards
2009-10-04 6:04 ` Ian Lance Taylor
2009-10-04 6:50 ` Paul Edwards
2009-10-04 15:38 ` Ulrich Weigand
2009-10-04 22:51 ` Paul Edwards
2009-10-05 13:15 ` Ulrich Weigand
2009-10-06 9:32 ` Paul Edwards
2009-10-06 13:15 ` Ulrich Weigand
2009-10-06 13:38 ` Paul Edwards
2009-10-06 14:01 ` Ulrich Weigand
2009-10-14 14:33 ` Paul Edwards
2009-10-19 14:19 ` Paul Edwards
2009-10-19 17:37 ` Ulrich Weigand
2009-10-20 14:18 ` Paul Edwards
2009-10-20 15:30 ` Ulrich Weigand
2009-11-12 14:03 ` Paul Edwards
2009-11-12 20:06 ` Ralf Wildenhues
2009-11-12 20:56 ` Paul Edwards
2009-11-13 11:43 ` Paul Edwards
2009-11-13 12:01 ` Ulrich Weigand
2009-11-13 12:18 ` Paul Edwards
2009-11-13 12:57 ` Ulrich Weigand
2009-11-14 8:52 ` Paul Edwards
2009-11-14 10:49 ` Ralf Wildenhues
2009-11-14 11:28 ` Paul Edwards
2009-11-22 0:51 ` Paolo Bonzini
2009-11-18 10:51 ` Paul Edwards
2009-11-19 14:27 ` Ulrich Weigand
2009-11-21 13:40 ` Paul Edwards
2009-11-23 10:33 ` i370 port - 3.4.6 to 4.4 upgrade attempt Paul Edwards
2009-11-23 10:43 ` Andreas Schwab
2009-11-23 15:43 ` Paolo Bonzini
2009-11-24 14:05 ` Ulrich Weigand
2009-11-24 14:36 ` Paul Edwards
2009-11-28 15:14 ` i370 port - music/sp - possible generic gcc problem Paul Edwards
2009-11-28 16:03 ` Richard Guenther
2009-11-28 16:35 ` Paul Edwards
2009-11-28 17:03 ` Richard Guenther
2009-11-28 23:44 ` Paul Edwards
2010-05-26 14:40 ` i370 port - status Paul Edwards
2021-03-14 5:55 ` negative indexes Paul Edwards
2021-03-14 8:05 ` Richard Biener
2021-03-14 8:12 ` Paul Edwards
2021-03-14 13:37 ` Richard Biener
[not found] ` <755065BE2A0B4B508DD3A262B2A83801@DESKTOP0OKG1VA>
2021-03-15 9:22 ` Richard Biener
2021-03-15 13:55 ` extended segments on 80386 Paul Edwards
2009-12-07 12:05 ` i370 port - 3.4.6 to 4.4 upgrade attempt Paul Edwards
2009-12-08 13:55 ` Ulrich Weigand
2009-11-15 14:22 ` i370 port - finally building Paul Edwards
2009-11-22 0:46 ` i370 port - constructing compile script Paolo Bonzini
2009-11-13 12:08 ` Ulrich Weigand
2009-10-05 13:17 ` Michael Matz
2009-10-05 13:38 ` Paul Edwards
2009-10-05 13:46 ` Michael Matz
2009-10-01 14:28 ` Paul Brook
2009-10-01 16:00 ` Paul Edwards
2009-10-01 18:36 ` Ian Lance Taylor
2009-10-01 23:43 ` Paul Edwards
2009-10-01 21:10 ` David Edelsohn
2009-10-01 22:22 ` Toon Moene
2009-10-02 0:19 ` Paul Edwards
2009-11-04 5:21 ` i370 port Paul Edwards
2009-11-04 16:47 ` Ulrich Weigand
2009-11-09 14:55 ` Paul Edwards
2009-11-09 15:57 ` Ian Lance Taylor
2009-11-09 23:10 ` Paul Edwards
2009-11-10 14:58 ` Paul Edwards
2009-11-10 15:36 ` Ian Lance Taylor
2009-11-10 15:51 ` Paul Edwards
2009-11-10 15:56 ` Ian Lance Taylor
2009-12-02 22:03 ` Paul Edwards
2011-08-13 8:34 ` Paul Edwards
2011-08-15 14:32 ` Ulrich Weigand
2011-08-15 15:26 ` Paul Edwards
2011-08-15 17:23 ` Ulrich Weigand
2011-08-16 11:20 ` Paul Edwards
2011-08-16 13:26 ` Ulrich Weigand
2011-08-18 12:15 ` Paul Edwards
2011-08-18 13:14 ` Ulrich Weigand
2011-08-18 14:18 ` Paul Edwards
-- strict thread matches above, loose matches on Subject: below --
2014-02-13 4:23 Paul Edwards
2012-04-07 5:45 Paul Edwards
2012-04-08 17:43 ` Ulrich Weigand
2014-02-11 17:01 ` Paul Edwards
2012-04-06 12:49 Paul Edwards
2012-04-06 18:16 ` Ulrich Weigand
2012-04-07 4:12 ` Paul Edwards
2012-04-06 5:51 Paul Edwards
2011-08-20 12:15 Paul Edwards
2011-08-22 12:23 ` Ulrich Weigand
2012-04-05 13:32 ` Paul Edwards
2012-04-06 18:13 ` Ulrich Weigand
2011-08-20 10:09 Paul Edwards
2011-08-20 7:44 Paul Edwards
2009-09-22 12:31 Paul Edwards
2009-08-23 8:50 Paul Edwards
2009-08-26 22:13 ` Henrik Sorensen
2009-06-05 12:45 Paul Edwards
2009-06-05 14:33 ` Joseph S. Myers
2009-06-05 14:57 ` Paul Edwards
2009-06-05 15:03 ` Joseph S. Myers
2009-06-05 15:24 ` Paul Edwards
2009-06-05 15:47 ` Joseph S. Myers
2017-03-31 10:34 ` Paul Edwards
2009-09-12 12:41 ` Paul Edwards
2009-06-05 15:21 ` Ulrich Weigand
2009-06-05 15:39 ` Paul Edwards
2009-06-05 15:49 ` Daniel Jacobowitz
2009-06-05 15:57 ` Paul Edwards
2009-06-05 20:20 ` Joseph S. Myers
2009-06-05 20:45 ` Paul Edwards
2009-06-06 15:00 ` Paul Edwards
2009-06-15 17:46 ` Ulrich Weigand
2009-06-19 0:06 ` Paul Edwards
2009-06-19 12:28 ` Ulrich Weigand
2009-07-18 11:28 ` Paul Edwards
2009-07-20 14:27 ` Ulrich Weigand
2009-08-08 12:04 ` Paul Edwards
2009-08-10 21:25 ` Ulrich Weigand
2009-08-11 0:34 ` Paul Edwards
2009-08-11 15:21 ` Ulrich Weigand
2009-08-12 11:52 ` Paul Edwards
2009-08-12 15:27 ` Paolo Bonzini
2009-08-12 16:35 ` Ulrich Weigand
2009-08-12 17:27 ` Paul Edwards
2009-08-12 17:56 ` Paolo Bonzini
2009-08-12 19:46 ` Ulrich Weigand
2009-08-12 20:31 ` Paul Edwards
2009-08-19 12:07 ` Paul Edwards
2009-08-19 12:27 ` Paolo Bonzini
2009-08-20 12:49 ` Paul Edwards
2009-08-20 22:48 ` Ulrich Weigand
2009-08-21 2:37 ` Paul Edwards
2009-08-21 16:46 ` Ulrich Weigand
2009-06-05 15:44 ` Joseph S. Myers
2009-06-05 15:52 ` Paul Edwards
2009-09-08 15:55 ` Paul Edwards
2009-09-14 15:32 ` Ulrich Weigand
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