From: Luis Machado <luis.machado@arm.com>
To: Tom de Vries <tdevries@suse.de>, gdb-patches@sourceware.org
Subject: Re: [PATCH][gdb/testsuite] Fix gdb.opt/clobbered-registers-O2.exp with gcc-12
Date: Tue, 24 May 2022 16:36:39 +0100 [thread overview]
Message-ID: <5ca5c802-141a-c3b3-da9f-8e102bc151e5@arm.com> (raw)
In-Reply-To: <20220524140704.GA23593@delia.home>
Hi,
On 5/24/22 15:07, Tom de Vries via Gdb-patches wrote:
> Hi,
>
> When running test-case gdb.opt/clobbered-registers-O2.exp with gcc-12, I run
> into:
> ...
> (gdb) PASS: gdb.opt/clobbered-registers-O2.exp: backtracing
> print operand0^M
> $1 = (unsigned int *) 0x7fffffffd070^M
> (gdb) print *operand0^M
> $2 = 4195541^M
> (gdb) FAIL: gdb.opt/clobbered-registers-O2.exp: print operand0
> ...
>
> The problem is that starting gcc-12, the assignments to x and y in main are
> optimized away:
> ...
> int main(void)
> {
> unsigned x, y;
>
> x = 13;
> y = 14;
> return (int)gen_movsd (&x, &y);
> ...
>
> Fix this by making x and y volatile.
>
> Note that the test-case intends to check the handling of debug info for
> optimized code in function gen_movsd, so inhibiting optimization in main
> doesn't interfere with that.
>
> Tested on x86_64-linux.
>
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29161
>
> Any comments?
Sorry, this was so long ago. I don't remember if we had a dwarf info assembler back in those days,
but it might be easier to simulate an optimized-away value by hand as opposed to doing some
contortionism with compilers and flags. But ...
>
> Thanks,
> - Tom
>
> [gdb/testsuite] Fix gdb.opt/clobbered-registers-O2.exp with gcc-12
>
> ---
> gdb/testsuite/gdb.opt/clobbered-registers-O2.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/gdb/testsuite/gdb.opt/clobbered-registers-O2.c b/gdb/testsuite/gdb.opt/clobbered-registers-O2.c
> index 7776024eb90..83cf2267d1e 100644
> --- a/gdb/testsuite/gdb.opt/clobbered-registers-O2.c
> +++ b/gdb/testsuite/gdb.opt/clobbered-registers-O2.c
> @@ -33,7 +33,7 @@ gen_movsd (unsigned * operand0, unsigned * operand1)
>
> int main(void)
> {
> - unsigned x, y;
> + volatile unsigned x, y;
>
> x = 13;
> y = 14;
... if the above fixes the problem, it should be fine. I'm OK with it.
prev parent reply other threads:[~2022-05-24 15:36 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-24 14:07 Tom de Vries
2022-05-24 15:36 ` Luis Machado [this message]
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