[Bug target/97106] [nvptx] Issues with weak aliases introduced by C++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97106
Tom de Vries changed:
What|Removed |Added
Status|UNCONFIRMED |RESOLVED
Target Milestone|--- |12.0
Resolution|--- |FIXED
--- Comment #5 from Tom de Vries ---
Using the test-case from comment 0 and:
...
/* { dg-additional-options "-foffload=-malias -foffload=-mptx=6.3 -O0" } */
...
I get:
...
$ strings test.exe | grep -i alias.alias
_ZN1VILi1EEC1ImvEET_,_ZN1VILi1EEC2ImvEET_;
...
so I see a normal alias, not a weak alias.
The test-case still fails in the abort.
Note that I get the same result with:
...
/* { dg-additional-options "-foffload=-mno-alias -foffload=-mptx=6.3 -O2" } */
...
There may be a problem with the test-case, there may be a problem with nvptx
c++ support, but the alias issue seems to have been addresses, so I'm closing
this one.
[Bug target/97106] [nvptx] Issues with weak aliases introduced by C++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97106 Bug 97106 depends on bug 97102, which changed state. Bug 97102 Summary: [nvptx] PTX JIT compilation failed when using aliases https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97102 What|Removed |Added Status|UNCONFIRMED |RESOLVED Resolution|--- |FIXED
[Bug target/97106] [nvptx] Issues with weak aliases introduced by C++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97106
--- Comment #4 from Tom de Vries ---
This:
...
$ cat alias.c
void __f ()
{
__builtin_printf ("hello\n");
}
void f () __attribute__ ((alias ("__f")));
int
main (void)
{
f ();
return 0;
}
...
works fine at -O0 and -O1:
...
$ ./gcc.sh -O0 ./alias.c
$ ./install/bin/nvptx-none-run a.out
hello
$ ./gcc.sh -O1 ./alias.c
$ ./install/bin/nvptx-none-run a.out
hello
...
but at -O2 we have:
...
$ ./gcc.sh -O2 ./alias.c
$ ./install/bin/nvptx-none-run a.out
fatal : Internal error: reference to deleted section
nvptx-run: cuLinkComplete failed: unknown error (CUDA_ERROR_UNKNOWN, 999)
...
This seems to be due to f/__f being inlined into main, after which we have an
alias declaration which is unused:
...
.visible .func f;
.alias f,__f;
...
Removing these two lines make the executable run fine again.
Note: same thing when using nvptx-none-run -O0.
Fixed by:
...
diff --git a/gcc/config/nvptx/nvptx.cc b/gcc/config/nvptx/nvptx.cc
index ab1f62359d4b..3e51bf15776c 100644
--- a/gcc/config/nvptx/nvptx.cc
+++ b/gcc/config/nvptx/nvptx.cc
@@ -77,6 +77,7 @@
#include "opts.h"
#include "tree-pretty-print.h"
#include "rtl-iter.h"
+#include "cgraph.h"
/* This file should be included last. */
#include "target-def.h"
@@ -7396,6 +7397,10 @@ nvptx_mem_local_p (rtx mem)
void
nvptx_asm_output_def_from_decls (FILE *stream, tree name, tree value)
{
+ if (!cgraph_node::get (name)->referred_to_p ())
+/* Prevent "Internal error: reference to deleted section". */
+return;
+
std::stringstream s;
write_fn_proto (s, false, get_fnname_from_decl (name), name);
fputs (s.str().c_str(), stream);
...
[Bug target/97106] [nvptx] Issues with weak aliases introduced by C++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97106
--- Comment #3 from Tom de Vries ---
With this additionally:
...
diff --git a/gcc/config/nvptx/nvptx.cc b/gcc/config/nvptx/nvptx.cc
index 1a89c1bc77f..2e1a2dad9fe 100644
--- a/gcc/config/nvptx/nvptx.cc
+++ b/gcc/config/nvptx/nvptx.cc
@@ -968,7 +968,8 @@ static void
write_fn_proto_1 (std::stringstream , bool is_defn,
const char *name, const_tree decl)
{
- write_fn_marker (s, is_defn, TREE_PUBLIC (decl), name);
+ if (lookup_attribute ("alias", DECL_ATTRIBUTES (decl)) == NULL)
+write_fn_marker (s, is_defn, TREE_PUBLIC (decl), name);
/* PTX declaration. */
if (DECL_EXTERNAL (decl))
...
I get a simplified libgomp/testsuite/libgomp.c-c++-common/pr96390.c to work.
That is, using only one level of alias indirection:
...
#pragma omp target map(from:n)
n = bar ();
...
With the original, two level alias indirection I get:
...
libgomp: Link error log ptxas fatal : Internal error: alias to unknown symbol
...
That seems to be consistent with the ptx manual, which dictates:
...
.alias fAlias, fAliasee;
Identifier fAliasee is a function symbol which must be defined in the same
module as .alias declaration.
...
[Bug target/97106] [nvptx] Issues with weak aliases introduced by C++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97106 --- Comment #2 from Tom de Vries --- Created attachment 52606 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52606=edit Tentative patch With this patch and: - current trunk - misa default set to sm_75 (so 3.1 multilib disabled, because sm_75 is not supported there) - patch "middle-end: Support ABIs that pass FP values as wider integers" to fix the build with sm_75 default - Tentative patch "[nvptx] Add warp sync at simt exit" from https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104783#c6 I get 100% pass rate on and sm_75 board for ovo testsuite: ... + ./ovo.sh report >> Overall result for test_result/2022-03-11_13-10_delia pass rate(%)test(#)success(#)compilation error(#)runtime error(#)wrong value(#)timeout(#) -- - -- -- 100%910 910 0 0 0 0 ...
[Bug target/97106] [nvptx] Issues with weak aliases introduced by C++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97106 --- Comment #1 from Tobias Burnus --- Suggested fix: 14:11 < amonakov> Tobias__: I think the proper way to solve this is define hooks for the backend to print something for aliases, and then have nvptx-ld.c resolve them 14:12 < amonakov> (right now the backend prints nothing without crashing, which is pretty bad: unhandled stuff should at least emit a diagnostic) That would be an alternative to CUDA 10's/ISA 6.3's .alias
