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Re: [PATCH 3/3] Simplify event-loop core, remove two-step event processing
- From: Pedro Alves <palves at redhat dot com>
- To: Patrick Palka <patrick at parcs dot ath dot cx>
- Cc: "gdb-patches at sourceware dot org" <gdb-patches at sourceware dot org>
- Date: Wed, 04 Feb 2015 11:51:18 +0100
- Subject: Re: [PATCH 3/3] Simplify event-loop core, remove two-step event processing
- Authentication-results: sourceware.org; auth=none
- References: <1422292759-22307-1-git-send-email-palves at redhat dot com> <1422292759-22307-4-git-send-email-palves at redhat dot com> <CA+C-WL_S7MTCb5rLWbpkMbR0JMQvH98mrWD-sZ50erNhVkN6JQ at mail dot gmail dot com>
On 02/03/2015 11:48 PM, Patrick Palka wrote:
> This patch causes a build failure when compiling GDB with GCC 4.9:
>
> /home/patrick/code/binutils-gdb/gdb/event-loop.c: In function
> âgdb_do_one_eventâ:
> /home/patrick/code/binutils-gdb/gdb/event-loop.c:296:10: error: âresâ
> may be used uninitialized in this function
> [-Werror=maybe-uninitialized]
> if (res > 0)
> ^
>
Bah, -O0 vs -O2. I've pushed the fix below.
-------
Subject: [PATCH] Fix build breakage due to event loop simplification
commit 70b66289 (Simplify event-loop core, remove two-step event
processing) causes a build failure when compiling GDB with gcc/-O2:
gdb/event-loop.c: In function âgdb_do_one_eventâ:
gdb/event-loop.c:296:10: error: âresâ may be used uninitialized in this function
[-Werror=maybe-uninitialized]
if (res > 0)
^
GCC isn't realizing that event_source_head can never be > 2 and that
therefore 'res' is always initialized in all possible paths. Adding a
default case that internal_error's makes GCC realize that.
Tested on x86_64 Fedora 20.
gdb/ChangeLog:
2015-02-04 Pedro Alves <palves@redhat.com>
Fix build breakage.
* event-loop.c (gdb_do_one_event): Add default switch case.
---
gdb/ChangeLog | 5 +++++
gdb/event-loop.c | 4 ++++
2 files changed, 9 insertions(+)
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 2266c11..1116853 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2015-02-04 Pedro Alves <palves@redhat.com>
+
+ Fix build breakage.
+ * event-loop.c (gdb_do_one_event): Add default switch case.
+
2015-02-03 Jan Kratochvil <jan.kratochvil@redhat.com>
Filter out inferior gcc option -fpreprocessed.
diff --git a/gdb/event-loop.c b/gdb/event-loop.c
index 7425b3a..a2b41a7 100644
--- a/gdb/event-loop.c
+++ b/gdb/event-loop.c
@@ -287,6 +287,10 @@ gdb_do_one_event (void)
/* Are there any asynchronous event handlers ready? */
res = check_async_event_handlers ();
break;
+ default:
+ internal_error (__FILE__, __LINE__,
+ "unexpected event_source_head %d",
+ event_source_head);
}
event_source_head++;
--
1.9.3