No description
4bb99ac688
This patch fixes a problem when using gdb + gdbserver, and trying
to break on a function when one of the (enum) parameters is equal
to a certain value, and the size of that enum is 1 byte.
(gdb) break mixed.adb:15 if light = green
Breakpoint 2 at 0x402d5a: file mixed.adb, line 15.
(gdb) cont
Continuing.
[Inferior 1 (process 9742) exited normally]
The debugger should have stopped once when our function was call
with light set to green.
Here is what happens: Because we're using a recent GDBserver,
GDB hands off the evaluation of the condition to GDBserver, by
providing it in the Z0 packet. This is what GDB sends:
$Z0,402d5a,1;X13,26000622100223ff1c16100219162022011327#cf
I decoded the condition as follow:
260006 reg 6 -> push
2210 const8 0x10 -> push
02 add (stack now has 1 element equal to reg6 + 16)
23ff1c const16 0xff1c
1610 ext 16 (sign extend 16 bits)
02 add (stack now has 1 element equal to reg6 + 16 - 228)
19 ref32: Pop as addr, push 32bit value at addr.
1620 ext 32 (sign extend 32 bits)
2201 const8 0x01
13 equal
27 end
The beginning of the agent expression can be explained by the address
of symbol "light":
(gdb) info addr light
Symbol "light" is a variable at frame base reg $rbp offset 16+-228.
However, the mistake is the "ext 32" operation (extend 32 bits),
because our variable is *not* 32bits, only 8:
(gdb) print light'size
$5 = 8
But the reason why GDB decides to use a 32bit extension is because
it overrides the symbol's type with a plain integer type in
ax-gdb.c:gen_usual_unary...
/* If the value is an enum or a bool, call it an integer. */
case TYPE_CODE_ENUM:
case TYPE_CODE_BOOL:
value->type = builtin_type (exp->gdbarch)->builtin_int;
break;
... before calling require_rvalue. And of course, that causes the
generator to generate a sizeof(int) extension of the result.
One way to fix this would be to use an integer type of the correct
size, but I do not understand why this is necessary. The two routines
that use that information to generate the opcode down the line are
gen_fetch (for a memory value), or gen_extend (for a register value).
And they both have handling of enums and bools.
So the fix we elected to implement was simply to remove that code.
gdb/ChangeLog:
* ax-gdb.c (gen_usual_unary): Remove special handling of
enum and bool types.
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| bfd | ||
| binutils | ||
| config | ||
| cpu | ||
| elfcpp | ||
| etc | ||
| gas | ||
| gdb | ||
| gold | ||
| gprof | ||
| include | ||
| intl | ||
| ld | ||
| libdecnumber | ||
| libiberty | ||
| opcodes | ||
| readline | ||
| sim | ||
| texinfo | ||
| .cvsignore | ||
| .gitignore | ||
| ChangeLog | ||
| compile | ||
| config-ml.in | ||
| config.guess | ||
| config.rpath | ||
| config.sub | ||
| configure | ||
| configure.ac | ||
| COPYING | ||
| COPYING.LIB | ||
| COPYING.LIBGLOSS | ||
| COPYING.NEWLIB | ||
| COPYING3 | ||
| COPYING3.LIB | ||
| depcomp | ||
| djunpack.bat | ||
| install-sh | ||
| libtool.m4 | ||
| ltgcc.m4 | ||
| ltmain.sh | ||
| ltoptions.m4 | ||
| ltsugar.m4 | ||
| ltversion.m4 | ||
| lt~obsolete.m4 | ||
| MAINTAINERS | ||
| Makefile.def | ||
| Makefile.in | ||
| Makefile.tpl | ||
| makefile.vms | ||
| missing | ||
| mkdep | ||
| mkinstalldirs | ||
| move-if-change | ||
| README | ||
| README-maintainer-mode | ||
| setup.com | ||
| src-release | ||
| symlink-tree | ||
| ylwrap | ||
README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.