Hi!
On 2022-07-14T19:39:40+0100, Jonathan Wakely <jwak...@redhat.com> wrote:
> On Thu, 14 Jul 2022 at 19:14, Thomas Schwinge <tho...@codesourcery.com> wrote:
>> I'm looking into building GCN, nvptx offloading libstdc++ [...]
>> While there is some experimental/incomplete/not-to-be-relied-on support
>> for PTX symbol aliases, we're currently generally running into
>> "error: alias definitions not supported in this configuration"
>> [...]/libstdc++-v3/libsupc++/tinfo.cc:55:1: error: alias definitions not
>> supported in this configuration
>> 55 | std::type_info::__equal (const std::type_info& arg) const
>> _GLIBCXX_NOEXCEPT
>> | ^~~
>> make[4]: *** [Makefile:777: tinfo.lo] Error 1
>>
>> That's 'libstdc++-v3/libsupc++/tinfo.cc':
>>
>> 1 // Methods for type_info for -*- C++ -*- Run Time Type Identification.
>> [...]
>> 39 // We can't rely on common symbols being shared between shared
>> objects.
>> 40 bool std::type_info::
>> 41 operator== (const std::type_info& arg) const _GLIBCXX_NOEXCEPT
>> 42 {
>> 43 #if __GXX_MERGED_TYPEINFO_NAMES
>> 44 return name () == arg.name ();
>> 45 #else
>> 46 /* The name() method will strip any leading '*' prefix. Therefore
>> 47 take care to look at __name rather than name() when looking for
>> 48 the "pointer" prefix. */
>> 49 return (&arg == this)
>> 50 || (__name[0] != '*' && (__builtin_strcmp (name (), arg.name ())
>> == 0));
>> 51 #endif
>> 52 }
>> 53
>> 54 bool
>> 55 std::type_info::__equal (const std::type_info& arg) const
>> _GLIBCXX_NOEXCEPT
>> 56 __attribute__((alias("_ZNKSt9type_infoeqERKS_")));
>> 57 #endif
>> [...]
>>
>> ..., so there's a manual alias from the line 55 function to the line 41
>> function (if I got that right).
>
> That's only there for backwards compatibility on ARM EABI and other
> targets that don't define __GXX_TYPEINFO_EQUALITY_INLINE==1.
>
> My suggestion would be to define that macro for the target.
Thanks, that did put me on the right track -- we shall define it this
way; indirectly.
Pushed to master branch commit 9837f62f066db532c9db6df38ccf2653d0c3a960
"nvptx: Use the usual '#define MAKE_DECL_ONE_ONLY(DECL) (DECL_WEAK (DECL) =
1)'",
see attached.
Grüße
Thomas
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>From 9837f62f066db532c9db6df38ccf2653d0c3a960 Mon Sep 17 00:00:00 2001
From: Thomas Schwinge <tho...@codesourcery.com>
Date: Thu, 14 Jul 2022 23:22:35 +0200
Subject: [PATCH] nvptx: Use the usual '#define MAKE_DECL_ONE_ONLY(DECL)
(DECL_WEAK (DECL) = 1)'
With this 'MAKE_DECL_ONE_ONLY' definition, we get 'SUPPORTS_ONE_ONLY', and thus
'__GXX_WEAK__', and thus '__GXX_TYPEINFO_EQUALITY_INLINE'. This unblocks build
of 'libstdc++-v3/libsupc++/tinfo.cc', which otherwise depends on symbol alias
support, which GCC/nvptx doesn't generally provide. Also, this gets us a
number of FAIL -> PASS progressions in the test suite.
Given that GCC/nvptx support for weak symbols isn't complete, we also get a few
more of the already-known
'error: PTX does not support weak declarations (only weak definitions)':
[-PASS:-]{+FAIL:+} g++.old-deja/g++.other/crash11.C -std=c++14 (test for excess errors)
[-PASS:-]{+FAIL:+} g++.old-deja/g++.other/crash11.C -std=c++17 (test for excess errors)
[-PASS:-]{+FAIL:+} g++.old-deja/g++.other/crash11.C -std=c++20 (test for excess errors)
[-PASS:-]{+FAIL:+} g++.old-deja/g++.other/crash11.C -std=c++98 (test for excess errors)
[-PASS:-]{+FAIL:+} g++.old-deja/g++.pt/crash29.C -std=c++14 (test for excess errors)
[-PASS:-]{+FAIL:+} g++.old-deja/g++.pt/crash29.C -std=c++17 (test for excess errors)
[-PASS:-]{+FAIL:+} g++.old-deja/g++.pt/crash29.C -std=c++20 (test for excess errors)
[-PASS:-]{+FAIL:+} g++.old-deja/g++.pt/crash29.C -std=c++98 (test for excess errors)
[-PASS:-]{+FAIL:+} 23_containers/map/56613.cc -std=gnu++17 (test for excess errors)
... as well as one more of the already-known
'sorry, unimplemented: target cannot support nonlocal goto':
PASS: g++.dg/tree-ssa/pr22488.C -std=gnu++14 (test for excess errors)
PASS: g++.dg/tree-ssa/pr22488.C -std=gnu++17 (test for excess errors)
PASS: g++.dg/tree-ssa/pr22488.C -std=gnu++20 (test for excess errors)
[-PASS:-]{+FAIL:+} g++.dg/tree-ssa/pr22488.C -std=gnu++98 (test for excess errors)
We shall look into these, later.
gcc/
* config/nvptx/nvptx.h (MAKE_DECL_ONE_ONLY): Define.
---
gcc/config/nvptx/nvptx.h | 3 +++
1 file changed, 3 insertions(+)
diff --git a/gcc/config/nvptx/nvptx.h b/gcc/config/nvptx/nvptx.h
index 129427e5654..407fd70f06a 100644
--- a/gcc/config/nvptx/nvptx.h
+++ b/gcc/config/nvptx/nvptx.h
@@ -319,6 +319,9 @@ struct GTY(()) machine_function
#define SUPPORTS_WEAK 1
+#define MAKE_DECL_ONE_ONLY(DECL) \
+ (DECL_WEAK (DECL) = 1)
+
/* The documentation states that ASM_OUTPUT_DEF_FROM_DECLS is used in
preference to ASM_OUTPUT_DEF if the tree nodes are available. However, we
need the tree nodes to emit the prototype, so at this point it's not clear
--
2.34.1
