From: hjl@lucon.org (H.J. Lu)
To: law@cygnus.com
Cc: gafton@redhat.com, egcs@cygnus.com, coxs@dg-rtp.dg.com,
crux@ohara.Informatik.RWTH-Aachen.DE
Subject: reg-stack.c problem
Date: Mon, 20 Apr 1998 13:06:00 -0000 [thread overview]
Message-ID: <m0yRK0o-00058vC@ocean.lucon.org> (raw)
In-Reply-To: <17624.893055503@hurl.cygnus.com>
> > Basically convert_regs () calls change_stack () with INSN to emit
> > some insn after INSN. But some insn has been added after INSN so
> > that change_stack () will emit some insn at the wrong place. As the
> > result, the floating point is broken on x86.
> This is an extremely confusing explanation, primarily because you
> use "insn"/INSN to refer to three different things.
>
> Basically is sounds like you have
>
> insn 1
> insn 2
>
>
> It sounds like we thought we wanted to insert after insn 1, but
> because of other reg-stack actions we really wanted to insert
> after insn 2.
>
> > This patch seems to fix it. Could someone please take a look? Given
> > the bugs we have seen in egcs 1.0.2, I suggest egcs 1.0.3 be made.
> I must confess I don't undersatnd reg-stack all that well. Assuming
> your analysis and explanation are correct, then I think your change
> is OK, though possibly incomplete.
>
> In particular I worry that we need to pass "new" instead of "insn"
> to the call to emit_pop_insn near the end of convert_regs. I think
> the call to goto_block_pat in convert_regs is OK.
You may be right.
>
> I also worry that there may be cases were we need to insert after
> insn 1 instead of after insn 2. But I don't know reg-stack well
> enough to know if that can actually happen.
I don't think that should happen.
>
> You might ask Bernd Schmidt or Stan Cox to look at the change and
> comment.
>
> I'm going to go ahead and hesitantly install the change, but further
> comments from folks that understand this code would be greatly
> appreciated.
>
How does this patch against egcs 1.0 in CVS sound?
Thanks.
--
H.J. Lu (hjl@gnu.org)
--
Mon Apr 20 08:02:56 1998 H.J. Lu (hjl@gnu.org)
(convert_regs): Abort if the last newly created insn is a JUMP
insn.
Call goto_block_pat (), emit_pop_insn () and straighten_stack ()
with NEW instead of INSN.
--- reg-stack.c.1 Sat Apr 18 18:23:12 1998
+++ reg-stack.c Mon Apr 20 08:01:58 1998
@@ -3108,6 +3108,9 @@ convert_regs ()
} while (insn != block_end[block]);
+ if (new != insn && GET_CODE (new) == JUMP_INSN)
+ abort ();
+
/* Something failed if the stack life doesn't match. */
GO_IF_HARD_REG_EQUAL (regstack.reg_set, block_out_reg_set[block], win);
@@ -3121,8 +3124,8 @@ convert_regs ()
jump target if the target block's stack order hasn't been set
yet. */
- if (GET_CODE (insn) == JUMP_INSN)
- goto_block_pat (insn, ®stack, PATTERN (insn));
+ if (GET_CODE (new) == JUMP_INSN)
+ goto_block_pat (new, ®stack, PATTERN (insn));
/* Likewise handle the case where we fall into the next block. */
@@ -3151,11 +3154,11 @@ convert_regs ()
for (reg = regstack.top; reg >= 0; reg--)
if (regstack.reg[reg] < value_reg_low
|| regstack.reg[reg] > value_reg_high)
- insn = emit_pop_insn (insn, ®stack,
+ insn = emit_pop_insn (new, ®stack,
FP_MODE_REG (regstack.reg[reg], DFmode),
emit_insn_after);
}
- straighten_stack (insn, ®stack);
+ straighten_stack (new, ®stack);
}
\f
/* Check expression PAT, which is in INSN, for label references. if
next prev parent reply other threads:[~1998-04-20 13:06 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <Pine.LNX.3.96.980414173903.3672J-100000@alien.redhat.com>
1998-04-15 19:57 ` egcs 1.0.2 is broken on x86 and a patch for it H.J. Lu
1998-04-20 0:56 ` Jeffrey A Law
1998-04-20 13:06 ` H.J. Lu
1998-04-20 13:06 ` H.J. Lu
1998-04-20 13:06 ` H.J. Lu [this message]
1998-04-22 9:05 ` Bernd Schmidt
1998-04-22 8:38 ` H.J. Lu
1998-04-23 21:12 ` Jim Wilson
1998-04-24 16:23 ` Jeffrey A Law
1998-04-24 16:23 ` H.J. Lu
1998-04-27 19:48 ` Jim Wilson
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