[PATCH v0 1/4] be more careful with concat_user_list()

From: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
To: linux-sparse@vger.kernel.org
Cc: Dibyendu Majumdar <mobile@majumdar.org.uk>,
	Christopher Li <sparse@chrisli.org>,
	Jeff Garzik <jeff@garzik.org>, Pekka Enberg <penberg@kernel.org>,
	Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Subject: [PATCH v0 1/4] be more careful with concat_user_list()
Date: Sat, 11 Mar 2017 16:47:22 +0100	[thread overview]
Message-ID: <20170311154725.87906-2-luc.vanoostenryck@gmail.com> (raw)
In-Reply-To: <20170311154725.87906-1-luc.vanoostenryck@gmail.com>

In convert_instruction_target(), once all users have been converted
the old user list is concatened to the one of the replacing pseudo.
But this pseudo may be one for which a user list is meaningless,
like PSEUDO_VAL.

While as such it's not a problem, it inhibit the reuse of the users
pointer for other uses.

Fix this by doing the concatenation only if the pseudo can have
an use-list.

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
---
 flow.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/flow.c b/flow.c
index 8111e1ae6..6878c0b4c 100644
--- a/flow.c
+++ b/flow.c
@@ -254,7 +254,8 @@ void convert_instruction_target(struct instruction *insn, pseudo_t src)
 			*pu->userp = src;
 		}
 	} END_FOR_EACH_PTR(pu);
-	concat_user_list(target->users, &src->users);
+	if (has_use_list(src))
+		concat_user_list(target->users, &src->users);
 	target->users = NULL;
 }
 
-- 
2.11.1

