Revert r227247 and r227228: "Add weak symbol support to RuntimeDyld".

This has wider implications than I expected when I reviewed the patch: It can
cause JIT crashes where clients have used the default value for AbortOnFailure
during symbol lookup. I'm currently investigating alternative approaches and I
hope to have this back in tree soon.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227287 91177308-0d34-0410-b5e6-96231b3b80d8

lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp

@@ -168,7 +168,6 @@ RuntimeDyldImpl::loadObjectImpl(const object::ObjectFile &Obj) {
     uint32_t Flags = I->getFlags();
 
     bool IsCommon = Flags & SymbolRef::SF_Common;
-    bool IsWeak = Flags & SymbolRef::SF_Weak;
     if (IsCommon)
       CommonSymbols.push_back(*I);
     else {
@@ -189,11 +188,6 @@ RuntimeDyldImpl::loadObjectImpl(const object::ObjectFile &Obj) {
           continue;
         StringRef SectionData;
         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);
@@ -204,11 +198,7 @@ RuntimeDyldImpl::loadObjectImpl(const object::ObjectFile &Obj) {
         SymbolInfo::Visibility Vis =
           (Flags & SymbolRef::SF_Exported) ?
             SymbolInfo::Default : SymbolInfo::Hidden;
-        if (!IsWeak) {
-          GlobalSymbolTable[Name] = SymbolInfo(SectionID, SectOffset, Vis);
-        } else {
-          WeakSymbolTable[Name] = SymbolInfo(SectionID, SectOffset, Vis);
-        }
+        GlobalSymbolTable[Name] = SymbolInfo(SectionID, SectOffset, Vis);
       }
     }
   }
@@ -778,21 +768,6 @@ void RuntimeDyldImpl::resolveExternalSymbols() {
                SymInfo.getOffset();
       }
 
-      // 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) {
-        RTDyldSymbolTable::const_iterator Loc = WeakSymbolTable.find(Name);
-        if (Loc != WeakSymbolTable.end()) {
-          SymbolInfo SymInfo = Loc->second;
-          Addr = getSectionLoadAddress(SymInfo.getSectionID()) + SymInfo.getOffset();
-          // 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] = SymInfo;
-        }
-      }
-
       // FIXME: Implement error handling that doesn't kill the host program!
       if (!Addr)
         report_fatal_error("Program used external function '" + Name +
@@ -809,7 +784,6 @@ void RuntimeDyldImpl::resolveExternalSymbols() {
 
     ExternalSymbolRelocations.erase(i);
   }
-  WeakSymbolTable.clear();
 }
 
 //===----------------------------------------------------------------------===//

lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp

@@ -947,7 +947,6 @@ relocation_iterator RuntimeDyldELF::processRelocationRef(
       break;
     }
     case SymbolRef::ST_Data:
-    case SymbolRef::ST_Function:
     case SymbolRef::ST_Unknown: {
       Value.SymbolName = TargetName.data();
       Value.Addend = Addend;

lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h

@@ -203,9 +203,6 @@ class RuntimeDyldImpl {
   // A global symbol table for symbols from all loaded modules.
   RTDyldSymbolTable GlobalSymbolTable;
 
-  // Like the global symbol table but for weak symbols
-  RTDyldSymbolTable WeakSymbolTable;
-
   // Keep a map of common symbols to their info pairs
   typedef std::vector<SymbolRef> CommonSymbolList;
 

unittests/ExecutionEngine/MCJIT/CMakeLists.txt

@@ -1,6 +1,5 @@
 set(LLVM_LINK_COMPONENTS
   Analysis
-  AsmParser
   Core
   ExecutionEngine
   IPO

unittests/ExecutionEngine/MCJIT/MCJITTest.cpp

@@ -13,7 +13,6 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ExecutionEngine/MCJIT.h"
-#include "llvm/Support/DynamicLibrary.h"
 #include "MCJITTestBase.h"
 #include "gtest/gtest.h"
 
@@ -200,45 +199,4 @@ TEST_F(MCJITTest, multiple_decl_lookups) {
   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"));
-}
-
-
 }

unittests/ExecutionEngine/MCJIT/MCJITTestBase.h

@@ -18,7 +18,6 @@
 #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"
@@ -28,8 +27,6 @@
 #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 {
 
@@ -341,22 +338,6 @@ class MCJITTestBase : public MCJITTestAPICommon, public TrivialModuleBuilder {
     assert(TheJIT.get() != NULL && "error creating MCJIT with EngineBuilder");
   }
 
-  void createJITFromAssembly(const char *Test) {
-    SMDiagnostic Error;
-    M = parseAssemblyString(Test, Error, Context);
-    M->setTargetTriple(Triple::normalize(BuilderTriple));
-
-    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;

unittests/ExecutionEngine/MCJIT/Makefile

@@ -9,7 +9,7 @@
 
 LEVEL = ../../..
 TESTNAME = MCJIT
-LINK_COMPONENTS := core asmparser ipo mcjit native support
+LINK_COMPONENTS := core ipo mcjit native support
 
 include $(LEVEL)/Makefile.config
 include $(LLVM_SRC_ROOT)/unittests/Makefile.unittest