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From: "blarsen at redhat dot com" <sourceware-bugzilla@sourceware.org>
To: gdb-prs@sourceware.org
Subject: [Bug record/30025] Adding an inferior when already recording makes
 GDB not handle SIGTRAP correctly
Date: Thu, 19 Jan 2023 15:42:51 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D30025

--- Comment #1 from B. Larsen <blarsen at redhat dot com> ---
Upon further inspection, its not nat the state of inferior 1 is corrupted.
Instead, GDB just doesn't handle the SIGTRAP correctly. Looking at the $PCs
when stepping to the factorial function, we have:

Program received signal SIGTRAP, Trace/breakpoint trap.=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20
0x0000000000401107 in fact (n=3D32767) at t.c:1=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20
1       int fact(int n){=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20
(gdb) p $pc=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20
$1 =3D (void (*)()) 0x401107 <fact+1>
(gdb) si
0x000000000040110a      1       int fact(int n){
(gdb)=20
0x000000000040110e      1       int fact(int n){
(gdb)=20
2           if (n<2) return n;
(gdb) p $pc
$2 =3D (void (*)()) 0x401111 <fact+11>

While the exact same session without recording inferior 1 looks like this:

(gdb) s
fact (n=3D5) at t.c:2
2           if (n<2) return n;
(gdb) p $pc
$1 =3D (void (*)()) 0x401111 <fact+11>

Seems clear to me that instead of continuing execution until we were at an
"is_stmt", GDB is just stopping at the instruction that received the sigtrap

--=20
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