mirror of
https://github.com/espressif/binutils-gdb.git
synced 2025-06-30 00:52:16 +08:00
d5f96005a6
The gdb.cp/classes.exp testcase has one test that tries to exercise
the case of calling a method on a variable that has been put in a
register.
See the declaration of small in classes.cc:
/* Try to get the compiler to allocate a class in a register. */
class small {
public:
int x;
int method ();
};
and the comment in classes.exp:
# This class is so small that an instance of it can fit in a register.
# When gdb tries to call a method, it gets embarrassed about taking
# the address of a register.
#
# TODO: I think that message should be a PASS, not an XFAIL.
# gdb prints an informative message and declines to do something
# impossible.
#
# The method call actually succeeds if the compiler allocates very
# small classes in memory instead of registers. So this test does
# not tell us anything interesting if the call succeeds.
#
# -- chastain 2003-12-31
And these comments:
https://gcc.gnu.org/legacy-ml/gcc/2010-05/msg00116.html
https://gcc.gnu.org/legacy-ml/gcc/2010-05/msg00117.html
"register keyword has other uses, e.g. for -O0 code variables
declared with register keyword can be put into registers, while
variables declared without it always get stack slots."
"I think it does, without optimization. There's some unique GDB
tests that use this. It causes them to be live between statements in
a machine register instead of always stored in stack slots."
The "register" keyword seems to be ignored by the compiler nowadays
even at -O0, though. With or without the register keyword, the
variable is given a stack slot, at least on x86-64 with GCC 9.
However, if we use the GCC extension to put the variable
in a specific variable:
https://gcc.gnu.org/onlinedocs/gcc-10.2.0/gcc/Local-Register-Variables.html#Local-Register-Variables
diff --git c/gdb/testsuite/gdb.cp/classes.cc w/gdb/testsuite/gdb.cp/classes.cc
index 5ea360e4d06..6dcf34689b8 100644
--- c/gdb/testsuite/gdb.cp/classes.cc
+++ w/gdb/testsuite/gdb.cp/classes.cc
@@ -629,7 +629,7 @@ register_class ()
/* We don't call any methods for v, so gcc version cygnus-2.3.3-930220
might put this variable in a register. This is a lose, though, because
it means that GDB can't call any methods for that variable. */
- register small v;
+ register small v asm ("rax");
then it works, and we get an XFAIL:
print v.method ()
Address requested for identifier "v" which is in register $rax
(gdb) XFAIL: gdb.cp/classes.exp: calling method for small class (PRMS 2972)
I think that what we should do here is move this test into its own
file, use that GCC syntax to force it to a register, and do as the
comment says -- issue a pass instead of an XFAIL.
That's what this commit does.
Note that we don't need -Wno-deprecated-register (nor -Wno-register)
anymore in the new testcase, because GNU register-asm local variables
don't trigger the warning, with either GCC or Clang.
gdb/testsuite/ChangeLog:
* gdb.cp/classes.exp: No longer pass -Wno-deprecated-register.
(do_tests): Remove "calling method for small class" test.
* gdb.cp/classes.cc (class small, small::method, marker_reg1)
(register_class): Delete.
(main): Don't call register_class.
* gdb.cp/call-method-register.exp: New file, based on bits removed
from classes.exp.
* gdb.cp/call-method-register.cc: New file, based on bits removed
from classes.cc.
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.