Index: lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp =================================================================== --- lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp +++ lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp @@ -175,6 +175,7 @@ uint32_t Flags = I->getFlags(); bool IsCommon = Flags & SymbolRef::SF_Common; + bool IsWeak = Flags & SymbolRef::SF_Weak; if (IsCommon) { // Add the common symbols to a list. We'll allocate them all below. if (!GlobalSymbolTable.count(Name)) { @@ -197,12 +198,22 @@ if (SI == Obj.section_end()) continue; Check(SI->getContents(SectionData)); + // TODO: It make make sense to delay emitting the section for weak + // symbols until they are actually required, but that's not possible + // currently, because we only know whether we will need the symbol + // in resolveRelocations, which happens after we have already finalized + // the Load. bool IsCode = SI->isText(); unsigned SectionID = findOrEmitSection(Obj, *SI, IsCode, LocalSections); DEBUG(dbgs() << "\tOffset: " << format("%p", (uintptr_t)SectOffset) << " flags: " << Flags << " SID: " << SectionID); - GlobalSymbolTable[Name] = SymbolLoc(SectionID, SectOffset); + if (!IsWeak) + { + GlobalSymbolTable[Name] = SymbolLoc(SectionID, SectOffset); + } else { + WeakSymbolTable[Name] = SymbolLoc(SectionID,SectOffset); + } } } DEBUG(dbgs() << "\tType: " << SymType << " Name: " << Name << "\n"); @@ -740,6 +751,21 @@ Addr = getSectionLoadAddress(SymLoc.first) + SymLoc.second; } + // If we didn't find the symbol yet, and it is present in the weak symbol + // table, the definition from this object file needs to be used, so emit + // it now + if (!Addr) { + SymbolTableMap::const_iterator Loc = WeakSymbolTable.find(Name); + if (Loc != WeakSymbolTable.end()) { + SymbolLoc SymLoc = Loc->second; + Addr = getSectionLoadAddress(SymLoc.first) + SymLoc.second; + // Since the weak symbol is now, materialized, add it to the + // GlobalSymbolTable. If somebody later asks the ExecutionEngine + // for the address of this symbol that's where it'll look + GlobalSymbolTable[Name] = SymLoc; + } + } + // FIXME: Implement error handling that doesn't kill the host program! if (!Addr) report_fatal_error("Program used external function '" + Name + @@ -756,6 +782,7 @@ ExternalSymbolRelocations.erase(i); } + WeakSymbolTable.clear(); } //===----------------------------------------------------------------------===// Index: lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp =================================================================== --- lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp +++ lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp @@ -946,6 +946,7 @@ break; } case SymbolRef::ST_Data: + case SymbolRef::ST_Function: case SymbolRef::ST_Unknown: { Value.SymbolName = TargetName.data(); Value.Addend = Addend; Index: lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h =================================================================== --- lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h +++ lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h @@ -184,6 +184,9 @@ typedef StringMap SymbolTableMap; SymbolTableMap GlobalSymbolTable; + // Like the global symbol table but for weak symbols + SymbolTableMap WeakSymbolTable; + // Pair representing the size and alignment requirement for a common symbol. typedef std::pair CommonSymbolInfo; // Keep a map of common symbols to their info pairs Index: unittests/ExecutionEngine/MCJIT/CMakeLists.txt =================================================================== --- unittests/ExecutionEngine/MCJIT/CMakeLists.txt +++ unittests/ExecutionEngine/MCJIT/CMakeLists.txt @@ -1,5 +1,6 @@ set(LLVM_LINK_COMPONENTS Analysis + AsmParser Core ExecutionEngine IPO Index: unittests/ExecutionEngine/MCJIT/MCJITTest.cpp =================================================================== --- unittests/ExecutionEngine/MCJIT/MCJITTest.cpp +++ unittests/ExecutionEngine/MCJIT/MCJITTest.cpp @@ -13,6 +13,7 @@ //===----------------------------------------------------------------------===// #include "llvm/ExecutionEngine/MCJIT.h" +#include "llvm/Support/DynamicLibrary.h" #include "MCJITTestBase.h" #include "gtest/gtest.h" @@ -199,4 +200,45 @@ EXPECT_EQ(A, B) << "Repeat calls to getPointerToFunction fail."; } +// Test weak symbol linking when the weak symbol is present in a shared +// library +TEST_F(MCJITTest, weak_symbol_present) { + SKIP_UNSUPPORTED_PLATFORM; + + int FakeWeakSymbol; + llvm::sys::DynamicLibrary::AddSymbol("FakeWeakSymbol", &FakeWeakSymbol); + createJITFromAssembly( + "$FakeWeakSymbol = comdat any\n" + "@FakeWeakSymbol = linkonce_odr global i32 42, comdat, align 4\n" + "define i32 @weak_test(i32* %arg) {\n" + " %r = icmp eq i32* %arg, @FakeWeakSymbol\n" + " %ret = zext i1 %r to i32\n" + " ret i32 %ret\n" + " }"); + + uint64_t Addr = TheJIT->getFunctionAddress("weak_test");; + EXPECT_TRUE(Addr != 0); + int32_t(*FuncPtr)(int32_t *) = (int32_t(*)(int32_t *))Addr; + EXPECT_EQ(FuncPtr(&FakeWeakSymbol),1); + EXPECT_TRUE(TheJIT->getGlobalValueAddress("FakeWeakSymbol") == 0); +} + +// Test weak symbol linking when the weak symbol is not present in a +// shared library +TEST_F(MCJITTest, weak_symbol_absent) { + SKIP_UNSUPPORTED_PLATFORM; + + SMDiagnostic Error; + createJITFromAssembly( + " $FakeWeakSymbol2 = comdat any\n" + " @FakeWeakSymbol2 = linkonce_odr global i32 42, comdat, align 4\n" + " define i32* @get_weak() {\n" + " ret i32* @FakeWeakSymbol2\n" + " }\n"); + void*(*FuncPtr)() = + (void*(*)(void))TheJIT->getFunctionAddress("get_weak"); + EXPECT_EQ(FuncPtr(),(void*)TheJIT->getGlobalValueAddress("FakeWeakSymbol2")); +} + + } Index: unittests/ExecutionEngine/MCJIT/MCJITTestBase.h =================================================================== --- unittests/ExecutionEngine/MCJIT/MCJITTestBase.h +++ unittests/ExecutionEngine/MCJIT/MCJITTestBase.h @@ -18,6 +18,7 @@ #define LLVM_UNITTESTS_EXECUTIONENGINE_MCJIT_MCJITTESTBASE_H #include "MCJITTestAPICommon.h" +#include "llvm/AsmParser/Parser.h" #include "llvm/Config/config.h" #include "llvm/ExecutionEngine/ExecutionEngine.h" #include "llvm/ExecutionEngine/SectionMemoryManager.h" @@ -27,6 +28,8 @@ #include "llvm/IR/Module.h" #include "llvm/IR/TypeBuilder.h" #include "llvm/Support/CodeGen.h" +#include "llvm/Support/SourceMgr.h" +#include "llvm/Support/raw_ostream.h" namespace llvm { @@ -338,6 +341,21 @@ assert(TheJIT.get() != NULL && "error creating MCJIT with EngineBuilder"); } + void createJITFromAssembly(const char *Test) { + SMDiagnostic Error; + M = parseAssemblyString(Test, Error, Context); + + std::string errMsg; + raw_string_ostream os(errMsg); + Error.print("", os); + + // A failure here means that the test itself is buggy. + if (!M) + report_fatal_error(os.str().c_str()); + + createJIT(std::move(M)); + } + CodeGenOpt::Level OptLevel; Reloc::Model RelocModel; CodeModel::Model CodeModel; Index: unittests/ExecutionEngine/MCJIT/Makefile =================================================================== --- unittests/ExecutionEngine/MCJIT/Makefile +++ unittests/ExecutionEngine/MCJIT/Makefile @@ -9,7 +9,7 @@ LEVEL = ../../.. TESTNAME = MCJIT -LINK_COMPONENTS := core ipo mcjit native support +LINK_COMPONENTS := core asmparser ipo mcjit native support include $(LEVEL)/Makefile.config include $(LLVM_SRC_ROOT)/unittests/Makefile.unittest