From ba5f6471d39e684fb740523651138a90a1b63cf9 Mon Sep 17 00:00:00 2001
From: Thomas Schwinge <thomas@codesourcery.com>
Date: Sun, 13 Nov 2022 14:19:30 +0100
Subject: [PATCH] nvptx: Support global constructors/destructors via 'collect2'
The function attributes 'constructor', 'destructor', and 'init_priority' now
work, as do the C++ features making use of this. Test cases with effective
target 'global_constructor' and 'init_priority' now generally work, and
'check-gcc-c++' test results greatly improve; no more "sorry, unimplemented:
global constructors not supported on this target".
This depends on <https://github.com/MentorEmbedded/nvptx-tools/pull/40> "'nm'"
generally, and for global destructors support: newlib
<https://inbox.sourceware.org/newlib/878rjqaku5.fsf@dem-tschwing-1.ger.mentorg.com/>
"nvptx: Implement '_exit' instead of 'exit'".
gcc/
* collect2.cc (write_c_file_glob): Allow for
'COLLECT2_MAIN_REFERENCE' override.
* config.gcc <case ${target} in nvptx-*>: Set 'use_collect2=yes'.
* config/nvptx/nvptx.h: Adjust.
gcc/testsuite/
* gcc.dg/no_profile_instrument_function-attr-1.c: GCC/nvptx is
'NO_DOT_IN_LABEL' but not 'NO_DOLLAR_IN_LABEL', so '$' may apper
in identifiers.
* lib/target-supports.exp
(check_effective_target_global_constructor): Enable for nvptx.
libgcc/
* config.host <case ${host} in nvptx-*>: Add 'crtbegin.o',
'crtend.o' to 'extra_parts'.
* config/nvptx/crt0.c: Invoke '__do_global_ctors',
'__do_global_dtors'.
* config/nvptx/crtstuff.c: New.
* config/nvptx/t-nvptx: Adjust.
---
gcc/collect2.cc | 4 ++
gcc/config.gcc | 1 +
gcc/config/nvptx/nvptx.h | 35 ++++++++++-
.../no_profile_instrument_function-attr-1.c | 2 +-
gcc/testsuite/lib/target-supports.exp | 3 +-
libgcc/config.host | 2 +-
libgcc/config/nvptx/crt0.c | 5 ++
libgcc/config/nvptx/crtstuff.c | 58 +++++++++++++++++++
libgcc/config/nvptx/t-nvptx | 15 ++++-
9 files changed, 118 insertions(+), 7 deletions(-)
create mode 100644 libgcc/config/nvptx/crtstuff.c
@@ -2238,8 +2238,12 @@ write_c_file_glob (FILE *stream, const char *name ATTRIBUTE_UNUSED)
fprintf (stream, "\tdereg_frame,\n");
fprintf (stream, "\t0\n};\n\n");
+# ifdef COLLECT2_MAIN_REFERENCE
+ fprintf (stream, "%s\n\n", COLLECT2_MAIN_REFERENCE);
+# else
fprintf (stream, "extern entry_pt %s;\n", NAME__MAIN);
fprintf (stream, "entry_pt *__main_reference = %s;\n\n", NAME__MAIN);
+# endif
}
#endif /* ! LD_INIT_SWITCH */
@@ -2783,6 +2783,7 @@ nvptx-*)
tm_file="${tm_file} newlib-stdint.h"
use_gcc_stdint=wrap
tmake_file="nvptx/t-nvptx"
+ use_collect2=yes
if test x$enable_as_accelerator = xyes; then
extra_programs="${extra_programs} mkoffload\$(exeext)"
tm_file="${tm_file} nvptx/offload.h"
@@ -35,7 +35,39 @@
'../../gcc.cc:asm_options', 'HAVE_GNU_AS'. */
#define ASM_SPEC "%{v}"
-#define STARTFILE_SPEC "%{mmainkernel:crt0.o%s}"
+#define STARTFILE_SPEC \
+ STARTFILE_SPEC_MMAINKERNEL \
+ " " STARTFILE_SPEC_CDTOR
+
+#define ENDFILE_SPEC \
+ ENDFILE_SPEC_CDTOR
+
+#define STARTFILE_SPEC_MMAINKERNEL "%{mmainkernel:crt0.o%s}"
+
+/* Support for global constructors/destructors is implemented via
+ 'collect2' and the following helpers. */
+
+#define STARTFILE_SPEC_CDTOR "crtbegin.o%s"
+
+#define ENDFILE_SPEC_CDTOR "crtend.o%s"
+
+/* nvptx does its own wrapping of 'main'
+ (see 'libgcc/config/nvptx/crt0.c:__main'). */
+#define HAS_INIT_SECTION
+
+/* For example with old Nvidia Tesla K20c, Driver Version: 361.93.02, the
+ function pointers stored in the '__CTOR_LIST__', '__DTOR_LIST__' arrays
+ evidently evaluate to NULL in JIT compilation. Avoiding the use of
+ assembler names ('write_list_with_asm') doesn't help, but defining a dummy
+ function next to the arrays apparently does work around this issue...
+
+ The default '__main_reference' synthesized by 'collect2' refers to our
+ 'crt0.o' '__main' function with incompatible signature:
+
+ error : Function '__main' not declared __global__ in all source files
+
+ Address both these issues via 'COLLECT2_MAIN_REFERENCE'. */
+#define COLLECT2_MAIN_REFERENCE "__attribute__((unused)) static void dummy () {}"
#define TARGET_CPU_CPP_BUILTINS() nvptx_cpu_cpp_builtins ()
@@ -354,7 +386,6 @@ struct GTY(()) machine_function
#define MOVE_MAX 8
#define MOVE_RATIO(SPEED) 4
#define FUNCTION_MODE QImode
-#define HAS_INIT_SECTION 1
/* The C++ front end insists to link against libstdc++ -- which we don't build.
Tell it to instead link against the innocuous libgcc. */
@@ -18,7 +18,7 @@ int main ()
return foo ();
}
-/* { dg-final { scan-tree-dump-times "__gcov0\[._\]main.* = PROF_edge_counter" 1 "optimized"} } */
+/* { dg-final { scan-tree-dump-times "__gcov0\[$._\]main.* = PROF_edge_counter" 1 "optimized"} } */
/* { dg-final { scan-tree-dump-times "__gcov_indirect_call_profiler_v" 1 "optimized" } } */
/* { dg-final { scan-tree-dump-times "__gcov_time_profiler_counter = " 1 "optimized" } } */
/* { dg-final { scan-tree-dump-times "__gcov_init" 1 "optimized" } } */
@@ -907,8 +907,7 @@ proc check_effective_target_nonlocal_goto {} {
# Return 1 if global constructors are supported, 0 otherwise.
proc check_effective_target_global_constructor {} {
- if { [istarget nvptx-*-*]
- || [istarget bpf-*-*] } {
+ if { [istarget bpf-*-*] } {
return 0
}
return 1
@@ -1499,7 +1499,7 @@ m32c-*-elf*)
;;
nvptx-*)
tmake_file="$tmake_file nvptx/t-nvptx"
- extra_parts="crt0.o"
+ extra_parts="crt0.o crtbegin.o crtend.o"
;;
*)
echo "*** Configuration ${host} not supported" 1>&2
@@ -19,6 +19,8 @@
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
+#include "gbl-ctors.h"
+
int *__exitval_ptr;
extern void __attribute__((noreturn)) exit (int status);
@@ -47,5 +49,8 @@ __main (int *rval_ptr, int argc, void **argv)
__nvptx_stacks[0] = stack + sizeof stack;
__nvptx_uni[0] = 0;
+ __do_global_ctors ();
+ atexit (__do_global_dtors);
+
exit (main (argc, argv));
}
new file mode 100644
@@ -0,0 +1,58 @@
+/* Copyright (C) 2022 Free Software Foundation, Inc.
+
+ This file is free software; you can redistribute it and/or modify it
+ under the terms of the GNU General Public License as published by the
+ Free Software Foundation; either version 3, or (at your option) any
+ later version.
+
+ This file is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ General Public License for more details.
+
+ Under Section 7 of GPL version 3, you are granted additional
+ permissions described in the GCC Runtime Library Exception, version
+ 3.1, as published by the Free Software Foundation.
+
+ You should have received a copy of the GNU General Public License and
+ a copy of the GCC Runtime Library Exception along with this program;
+ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include "gbl-ctors.h"
+
+/* The common 'crtstuff.c' doesn't quite provide what we need, so we roll our
+ own.
+
+ There's no technical reason in this configuration here to split the two
+ functions '__do_global_ctors' and '__do_global_ctors' into two separate
+ files (via 'CRT_BEGIN' and 'CRT_END'): 'crtbegin.o' and 'crtend.o', but we
+ do so anyway, for symmetry with other configurations. */
+
+#ifdef CRT_BEGIN
+
+void
+__do_global_ctors (void)
+{
+ DO_GLOBAL_CTORS_BODY;
+}
+
+#elif defined(CRT_END) /* ! CRT_BEGIN */
+
+void
+__do_global_dtors (void)
+{
+ /* In this configuration here, there's no way that "this routine is run more
+ than once [...] when exit is called recursively": for nvptx target, the
+ call to '__do_global_dtors' is registered via 'atexit', which doesn't
+ re-enter a function already run.
+ Therefore, we do *not* "arrange to remember where in the list we left off
+ processing". */
+ func_ptr *p;
+ for (p = __DTOR_LIST__ + 1; *p; )
+ (*p++) ();
+}
+
+#else /* ! CRT_BEGIN && ! CRT_END */
+#error "One of CRT_BEGIN or CRT_END must be defined."
+#endif
@@ -3,7 +3,7 @@ LIB2ADD=$(srcdir)/config/nvptx/reduction.c \
$(srcdir)/config/nvptx/atomic.c
LIB2ADDEH=
-LIB2FUNCS_EXCLUDE=__main
+LIB2FUNCS_EXCLUDE=
crt0.o: $(srcdir)/config/nvptx/crt0.c
$(crt_compile) -c $<
@@ -12,3 +12,16 @@ crt0.o: $(srcdir)/config/nvptx/crt0.c
# support it, and it may cause the build to fail, because of alloca usage, for
# example.
INHIBIT_LIBC_CFLAGS = -Dinhibit_libc
+
+# Support for global constructors/destructors is implemented via
+# 'collect2' and the following helpers.
+
+LIB2FUNCS_EXCLUDE += __main
+
+CUSTOM_CRTSTUFF = yes
+
+crtbegin.o: $(srcdir)/config/nvptx/crtstuff.c
+ $(crt_compile) $(CRTSTUFF_T_CFLAGS) -c $< -DCRT_BEGIN
+
+crtend.o: $(srcdir)/config/nvptx/crtstuff.c
+ $(crt_compile) $(CRTSTUFF_T_CFLAGS) -c $< -DCRT_END
--
2.25.1