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Tom de Vries 6173d6a696 [gdb/testsuite] Compile compile-ifunc.c with -Wno-attribute-alias
Consider the following test-case:
...
$ cat 1.c
typedef int (*final_t) (int arg);
int final (int arg)
  { return arg + 1; }
final_t gnu_ifunc (void)
  { return final; }
int gnu_ifunc_alias (int) __attribute__ ((ifunc ("gnu_ifunc")));
int main (void)
  { return gnu_ifunc_alias (10); }
...
with result:
...
$ gcc 1.c
$ ./a.out; echo $?
11
...

The test-case uses the ifunc attribute, but there's another solution using
%gnu_indirect_function.  Consider 2.c and 3.c:
...
$ cat 2.c
typedef int (*final_t) (int arg);
int final (int arg)
  { return arg + 1; }
asm (".type gnu_ifunc, %gnu_indirect_function");
final_t gnu_ifunc (void)
  { return final; }
$ cat 3.c
extern int gnu_ifunc (int);
int main (void)
  { return gnu_ifunc (10); }
...

However, it can be inconvenient to have seperate files for the incompatible
decls of gnu_ifunc, so we can use this in a single file like this:
...
$ cat 4.c
typedef int (*final_t) (int arg);
int final (int arg)
  { return arg + 1; }
asm (".type gnu_ifunc, %gnu_indirect_function");
final_t gnu_ifunc (void)
  { return final; }
extern int gnu_ifunc_alias (int arg) __attribute__ ((alias ("gnu_ifunc")));
int main (void)
  { return gnu_ifunc_alias (10); }
...

This alias trick works ok at -O0, but not at -O2:
...
$ gcc 4.c
$ ./a.out; echo $?
11
$ gcc 4.c
$ ./a.out; echo $?
176
...
and produces a warning with gcc-8 and later:
...
$ gcc-8 4.c
4.c:7:12: warning: 'gnu_ifunc_alias' alias between functions of incompatible \
  types 'int(int)' and 'int (*(void))(int)' [-Wattribute-alias]
 extern int gnu_ifunc_alias (int arg) __attribute__ ((alias ("gnu_ifunc")));
            ^~~~~~~~~~~~~~~
4.c:5:9: note: aliased declaration here
 final_t gnu_ifunc (void)
         ^~~~~~~~~
...
The warning is correct, but the mismatch is intentional.

The last variant (%gnu_indirect_function + alias) is used in
gdb.compile/compile-ifunc.c, so we run into the warning with recent gcc.

Fix the warning by compiling with -Wno-attribute-alias.

Tested the test-case on x86_64-linux with gcc-10, and observed I no longer see
the warning:
...
Running src/gdb/testsuite/gdb.compile/compile-ifunc.exp ...

                === gdb Summary ===

nr of untested testcases         1
...

gdb/testsuite/ChangeLog:

2020-05-06  Tom de Vries  <tdevries@suse.de>

	* gdb.compile/compile-ifunc.exp: Use -Wno-attribute-alias.
2020-05-06 05:27:48 +02:00
bfd Automatic date update in version.in 2020-05-06 00:00:06 +00:00
binutils Restore readelf's warnings that describe real problems with the file being examined. Fix bug displaying empty file name tables. 2020-05-05 16:16:03 +01:00
config Sync config and libiberty with GCC 2020-04-29 14:25:36 -07:00
contrib
cpu cpu,gas,opcodes: support for eBPF JMP32 instruction class 2020-04-16 09:52:57 +02:00
elfcpp
etc
gas Restore readelf's warnings that describe real problems with the file being examined. Fix bug displaying empty file name tables. 2020-05-05 16:16:03 +01:00
gdb [gdb/testsuite] Compile compile-ifunc.c with -Wno-attribute-alias 2020-05-06 05:27:48 +02:00
gdbserver Implement debugging of WOW64 processes in gdbserver 2020-04-30 18:30:20 +02:00
gdbsupport Fix typo (thead -> thread) 2020-04-28 11:38:26 +02:00
gnulib
gold gold: Compile common tests with -fcommon 2020-05-02 06:48:26 -07:00
gprof Updated Serbian translation for the gprof subdirectory 2020-04-01 14:37:02 +01:00
include AArch64: add GAS support for UDF instruction 2020-04-30 15:47:30 +01:00
intl
ld [binutils-gdb][ld][AArch64] Fix group_sections algorithm 2020-05-04 15:51:56 +01:00
libctf
libdecnumber
libiberty Sync config and libiberty with GCC 2020-04-29 14:25:36 -07:00
opcodes AArch64: add GAS support for UDF instruction 2020-04-30 15:47:30 +01:00
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sim
texinfo
zlib
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ar-lib
ChangeLog Since the pdp11-aout target does not support gdb, gdbserver or gprof these should be excluded in configure. 2020-04-21 10:27:50 +01:00
compile
config-ml.in
config.guess
config.rpath
config.sub
configure Since the pdp11-aout target does not support gdb, gdbserver or gprof these should be excluded in configure. 2020-04-21 10:27:50 +01:00
configure.ac Since the pdp11-aout target does not support gdb, gdbserver or gprof these should be excluded in configure. 2020-04-21 10:27:50 +01:00
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		   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
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	./configure 
	make

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	CC=gcc ./configure
	make

A similar example using csh:

	setenv CC gcc
	./configure
	make

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the Free Software Foundation, Inc.  See the file COPYING or
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