From: Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
To: gdb-patches@sourceware.org
Subject: [PATCH] testsuite, mi: avoid a clang bug in 'user-selected-context-sync.exp'
Date: Mon, 29 Mar 2021 16:03:35 +0200 [thread overview]
Message-ID: <1617026615-4257-1-git-send-email-tankut.baris.aktemur@intel.com> (raw)
This test causes several timeouts for Clang, taking too long time to
finish. The reason is, for an infinite loop of the form
while(1); /* suppose this is line 30. */
Clang generates code that looks like
0x00000000004004d4 <+4>: jmp 0x4004d9 <loop+9>
0x00000000004004d9 <+9>: jmp 0x4004d9 <loop+9>
So, the real loop is the instruction at address 0x4004d9. But a
breakpoint that's defined at the loop line (assume line 30 in this
case) is inserted at address 0x4004d4.
(gdb) break 30
Breakpoint 1 at 0x4004d4: file test.c, line 30.
Therefore, continuing a thread that was spinning on the loop does not hit
the breakpoint. The bug is reported at
https://bugs.llvm.org/show_bug.cgi?id=49614
Tweak the infinite loop to spin on a variable to avoid this bug. The
test is unrelated to the bug.
gdb/testsuite/ChangeLog:
2021-03-29 Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
* gdb.mi/user-selected-context-sync.exp: Spin on a variable in
the infinite loop to avoid a Clang bug.
---
gdb/testsuite/gdb.mi/user-selected-context-sync.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/gdb/testsuite/gdb.mi/user-selected-context-sync.c b/gdb/testsuite/gdb.mi/user-selected-context-sync.c
index 500a118a2dc..0f8a966f69d 100644
--- a/gdb/testsuite/gdb.mi/user-selected-context-sync.c
+++ b/gdb/testsuite/gdb.mi/user-selected-context-sync.c
@@ -27,7 +27,8 @@ static pthread_barrier_t barrier;
static void
child_sub_function (void)
{
- while (1); /* thread loop line */
+ int spin = 1;
+ while (spin); /* thread loop line */
}
static void *
@@ -57,7 +58,8 @@ main (void)
pthread_barrier_wait (&barrier);
- while (1); /* main break line */
+ int spin = 1;
+ while (spin); /* main break line */
return 0;
}
--
2.17.1
next reply other threads:[~2021-03-29 14:04 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-29 14:03 Tankut Baris Aktemur [this message]
2021-03-29 14:36 ` Simon Marchi
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1617026615-4257-1-git-send-email-tankut.baris.aktemur@intel.com \
--to=tankut.baris.aktemur@intel.com \
--cc=gdb-patches@sourceware.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).