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https://github.com/c64scene-ar/llvm-6502.git
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6da21c0e33
That causes references to them to be weak references which can collapse to null if no definition is provided. We call these functions unconditionally, so a definition *must* be provided. Make the definitions provided in the .cpp file weak by re-declaring them as weak just prior to defining them. This should keep compilers which cannot attach the weak attribute to the definition happy while actually resolving the symbols correctly during the link. You might ask yourself upon reading this commit log: how did *any* of this work before? Well, fun story. It turns out we have some code in Support (BumpPtrAllocator) which both uses virtual dispatch and has out-of-line vtables used by that virtual dispatch. If you move the virtual dispatch into its header in *just* the right way, the optimizer gets to devirtualize, and remove all references to the vtable. Then the sad part: the references to this one vtable were the only strong symbol uses in the support library for llvm-tblgen AFAICT. At least, after doing something just like this, these symbols stopped getting their weak definition and random calls to them would segfault instead. Yay software. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205137 91177308-0d34-0410-b5e6-96231b3b80d8
74 lines
2.6 KiB
C++
74 lines
2.6 KiB
C++
//===- llvm/Support/Valgrind.h - Communication with Valgrind -----*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// Methods for communicating with a valgrind instance this program is running
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// under. These are all no-ops unless LLVM was configured on a system with the
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// valgrind headers installed and valgrind is controlling this process.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_VALGRIND_H
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#define LLVM_SUPPORT_VALGRIND_H
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#include "llvm/Config/llvm-config.h"
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#include "llvm/Support/Compiler.h"
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#include <stddef.h>
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#if LLVM_ENABLE_THREADS != 0 && !defined(NDEBUG)
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// tsan (Thread Sanitizer) is a valgrind-based tool that detects these exact
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// functions by name.
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extern "C" {
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void AnnotateHappensAfter(const char *file, int line, const volatile void *cv);
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void AnnotateHappensBefore(const char *file, int line, const volatile void *cv);
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void AnnotateIgnoreWritesBegin(const char *file, int line);
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void AnnotateIgnoreWritesEnd(const char *file, int line);
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}
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#endif
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namespace llvm {
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namespace sys {
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// True if Valgrind is controlling this process.
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bool RunningOnValgrind();
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// Discard valgrind's translation of code in the range [Addr .. Addr + Len).
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// Otherwise valgrind may continue to execute the old version of the code.
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void ValgrindDiscardTranslations(const void *Addr, size_t Len);
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#if LLVM_ENABLE_THREADS != 0 && !defined(NDEBUG)
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// Thread Sanitizer is a valgrind tool that finds races in code.
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// See http://code.google.com/p/data-race-test/wiki/DynamicAnnotations .
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// This marker is used to define a happens-before arc. The race detector will
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// infer an arc from the begin to the end when they share the same pointer
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// argument.
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#define TsanHappensBefore(cv) \
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AnnotateHappensBefore(__FILE__, __LINE__, cv)
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// This marker defines the destination of a happens-before arc.
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#define TsanHappensAfter(cv) \
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AnnotateHappensAfter(__FILE__, __LINE__, cv)
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// Ignore any races on writes between here and the next TsanIgnoreWritesEnd.
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#define TsanIgnoreWritesBegin() \
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AnnotateIgnoreWritesBegin(__FILE__, __LINE__)
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// Resume checking for racy writes.
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#define TsanIgnoreWritesEnd() \
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AnnotateIgnoreWritesEnd(__FILE__, __LINE__)
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#else
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#define TsanHappensBefore(cv)
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#define TsanHappensAfter(cv)
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#define TsanIgnoreWritesBegin()
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#define TsanIgnoreWritesEnd()
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#endif
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}
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}
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#endif
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