From: Eric Botcazou <ebotcazou@adacore.com>
To: gcc@gcc.gnu.org
Subject: Problem with SSA inlining and default defs
Date: Sun, 16 Dec 2007 18:01:00 -0000 [thread overview]
Message-ID: <200712161854.29543.ebotcazou@adacore.com> (raw)
[-- Attachment #1: Type: text/plain, Size: 679 bytes --]
Hi,
How SSA inlining and default defs for uninitialized variables are supposed to
interact? Suppose you have the following situation
BB0 ...
| \
(ab) | BB1 s_2 = f(s_1(D))
| /
BB2 s_3 = PHI <s_1(D), s2>
in a function that gets inlined into a loop. The liveness of s_1(D) in BB0
will propagate to BB2 along the backwards edge and you get overlapping live
ranges for s_1(D) and s_3. If s_1(D) is SSA_NAME_OCCURS_IN_ABNORMAL_PHI, the
compilation will abort during SSA coalescing because they must be coalesced.
This is on the mainline, Ada testcase attached, run 'gnatchop' on it and
compile at -O -gnatp.
Thanks in advance.
--
Eric Botcazou
[-- Attachment #2: p.ada --]
[-- Type: text/plain, Size: 508 bytes --]
package Q is
procedure Read(S : out Integer);
procedure Restore(S : in out Integer);
end Q;
package P is
type Int_Ptr is access all Integer;
procedure Exec(P : Int_Ptr);
end P;
with Q; use Q;
package body P is
procedure Lock is
S : Integer;
begin
Read(S);
Restore(S);
exception
when others => Restore(S);
end;
procedure Exec(P : Int_Ptr) is
begin
while P /= NULL loop
Lock;
end loop;
end;
end P;
next reply other threads:[~2007-12-16 17:53 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-16 18:01 Eric Botcazou [this message]
2007-12-16 18:10 ` Jakub Jelinek
2007-12-16 18:27 ` Eric Botcazou
2007-12-16 19:45 ` Jakub Jelinek
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