Re: toolchain/54820 gdb broken

[Rin Okuyama <rokuyama.rk%gmail.com@localhost>]

The following reply was made to PR toolchain/54820; it has been noted by GNATS.

From: Rin Okuyama <rokuyama.rk%gmail.com@localhost>
To: "gnats-bugs%NetBSD.org@localhost" <gnats-bugs%NetBSD.org@localhost>
Cc: 
Subject: Re: toolchain/54820 gdb broken
Date: Wed, 29 Apr 2020 19:54:36 +0900

 Hi,
 
 I found similar crashes occur also for earmv7hf (little endian), and
 simple single-stepping like this:
 
 ------------------------------------------------------------
 # uname -p
 earmv7hf
 # gdb ./hello
 GNU gdb (GDB) 8.3
 ...snip...
 Reading symbols from ./hello...
 (gdb) b main
 Breakpoint 1 at 0x106ac: file hello.c, line 7.
 (gdb) r
 Starting program: /root/hello
 
 Breakpoint 1, main () at hello.c:7
 7               printf("Hello, World!\n");
 (gdb) s
 puts (s=0x1077c "Hello, World!") at /build/src/lib/libc/stdio/puts.c:61
 61              const void *vs = s;
 ...snip...
 __flockfile_internal (fp=fp@entry=0xf0608bf8 <__sF+88>,
      internal=internal@entry=1) at /build/src/lib/libc/stdio/flockfile.c:100
 100             if (__isthreaded == 0)
 (gdb) s
 terminate called after throwing an instance of 'gdb_exception_RETURN_MASK_ERROR'
 puts ([ 272534.1561499] sorry, pid 12856 was killed: orphaned traced process
 [1]   Abort trap (core dumped) gdb ./hello
 ------------------------------------------------------------
 
 However, this does not occur for earmv7{,eb} nor earmv6hf{,eb}. Also,
 gdb does not crash when compiled with GCC8 and -O0, or GCC7 and -O2.
 
 Finally, I found that single file, dwarf2expr.c, is miscompiled with
 GCC 8.4 with -O[12]. I will commit a workaround and document it in
 doc/HACKS.
 
 Thanks,
 rin