From 72db10a9959431a710712f64d4b98299ab5a022d Mon Sep 17 00:00:00 2001 From: Rafael Espindola Date: Wed, 26 Mar 2014 06:14:40 +0000 Subject: [PATCH] Revert "Prevent alias from pointing to weak aliases." This reverts commit r204781. I will follow up to with msan folks to see what is what they were trying to do with aliases to weak aliases. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204784 91177308-0d34-0410-b5e6-96231b3b80d8 --- docs/LangRef.rst | 4 --- include/llvm/IR/GlobalAlias.h | 16 ++++++--- lib/CodeGen/SelectionDAG/SelectionDAG.cpp | 2 +- lib/ExecutionEngine/JIT/JITEmitter.cpp | 2 +- lib/IR/Globals.cpp | 35 +++++++++++-------- lib/IR/Verifier.cpp | 10 ++---- lib/Target/PowerPC/PPCAsmPrinter.cpp | 12 +++---- lib/Target/PowerPC/PPCFastISel.cpp | 2 +- lib/Target/PowerPC/PPCISelDAGToDAG.cpp | 4 +-- lib/Target/TargetMachine.cpp | 2 +- lib/Target/X86/X86FastISel.cpp | 2 +- lib/Target/X86/X86ISelLowering.cpp | 2 +- lib/Target/XCore/XCoreISelLowering.cpp | 2 +- .../Instrumentation/DataFlowSanitizer.cpp | 3 +- test/CodeGen/X86/dllexport-x86_64.ll | 2 +- test/CodeGen/X86/dllexport.ll | 2 +- test/Feature/aliases.ll | 2 +- test/Transforms/GlobalOpt/alias-resolve.ll | 15 +++----- 18 files changed, 61 insertions(+), 58 deletions(-) diff --git a/docs/LangRef.rst b/docs/LangRef.rst index b0b8bfebee5..c959f56ef11 100644 --- a/docs/LangRef.rst +++ b/docs/LangRef.rst @@ -681,10 +681,6 @@ the aliasee. The aliasee must be a definition. -Aliases are not allowed to point to aliases with linkages that can be -overridden. Since they are only a second name, the possibility of the -intermediate alias being overridden cannot be represented in an object file. - .. _namedmetadatastructure: Named Metadata diff --git a/include/llvm/IR/GlobalAlias.h b/include/llvm/IR/GlobalAlias.h index 2ca481a515f..81777af3869 100644 --- a/include/llvm/IR/GlobalAlias.h +++ b/include/llvm/IR/GlobalAlias.h @@ -64,15 +64,23 @@ public: Constant *getAliasee() { return getOperand(0); } - - /// This method tries to ultimately resolve the alias by going through the - /// aliasing chain and trying to find the very last global. Returns NULL if a - /// cycle was found. + /// getAliasedGlobal() - Aliasee can be either global or bitcast of + /// global. This method retrives the global for both aliasee flavours. GlobalValue *getAliasedGlobal(); const GlobalValue *getAliasedGlobal() const { return const_cast(this)->getAliasedGlobal(); } + /// resolveAliasedGlobal() - This method tries to ultimately resolve the alias + /// by going through the aliasing chain and trying to find the very last + /// global. Returns NULL if a cycle was found. If stopOnWeak is false, then + /// the whole chain aliasing chain is traversed, otherwise - only strong + /// aliases. + GlobalValue *resolveAliasedGlobal(bool stopOnWeak = true); + const GlobalValue *resolveAliasedGlobal(bool stopOnWeak = true) const { + return const_cast(this)->resolveAliasedGlobal(stopOnWeak); + } + static bool isValidLinkage(LinkageTypes L) { return isExternalLinkage(L) || isLocalLinkage(L) || isWeakLinkage(L) || isLinkOnceLinkage(L); diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp index 52806235fd2..61961d8ca2d 100644 --- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp +++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp @@ -1172,7 +1172,7 @@ SDValue SelectionDAG::getGlobalAddress(const GlobalValue *GV, SDLoc DL, if (!GVar) { // If GV is an alias then use the aliasee for determining thread-localness. if (const GlobalAlias *GA = dyn_cast(GV)) - GVar = dyn_cast_or_null(GA->getAliasedGlobal()); + GVar = dyn_cast_or_null(GA->resolveAliasedGlobal(false)); } unsigned Opc; diff --git a/lib/ExecutionEngine/JIT/JITEmitter.cpp b/lib/ExecutionEngine/JIT/JITEmitter.cpp index 9d215ec96ae..4b2f012eafb 100644 --- a/lib/ExecutionEngine/JIT/JITEmitter.cpp +++ b/lib/ExecutionEngine/JIT/JITEmitter.cpp @@ -688,7 +688,7 @@ void *JITEmitter::getPointerToGlobal(GlobalValue *V, void *Reference, return TheJIT->getOrEmitGlobalVariable(GV); if (GlobalAlias *GA = dyn_cast(V)) - return TheJIT->getPointerToGlobal(GA->getAliasedGlobal()); + return TheJIT->getPointerToGlobal(GA->resolveAliasedGlobal(false)); // If we have already compiled the function, return a pointer to its body. Function *F = cast(V); diff --git a/lib/IR/Globals.cpp b/lib/IR/Globals.cpp index f338dd76aaa..11152d5d6c2 100644 --- a/lib/IR/Globals.cpp +++ b/lib/IR/Globals.cpp @@ -236,10 +236,10 @@ void GlobalAlias::setAliasee(Constant *Aliasee) { setOperand(0, Aliasee); } -static GlobalValue *getAliaseeGV(GlobalAlias *GA) { - Constant *C = GA->getAliasee(); - assert(C && "Must alias something"); - +GlobalValue *GlobalAlias::getAliasedGlobal() { + Constant *C = getAliasee(); + if (C == 0) return 0; + if (GlobalValue *GV = dyn_cast(C)) return GV; @@ -248,23 +248,30 @@ static GlobalValue *getAliaseeGV(GlobalAlias *GA) { CE->getOpcode() == Instruction::AddrSpaceCast || CE->getOpcode() == Instruction::GetElementPtr) && "Unsupported aliasee"); - + return cast(CE->getOperand(0)); } -GlobalValue *GlobalAlias::getAliasedGlobal() { +GlobalValue *GlobalAlias::resolveAliasedGlobal(bool stopOnWeak) { SmallPtrSet Visited; - GlobalAlias *GA = this; + // Check if we need to stop early. + if (stopOnWeak && mayBeOverridden()) + return this; + + GlobalValue *GV = getAliasedGlobal(); + Visited.insert(GV); + + // Iterate over aliasing chain, stopping on weak alias if necessary. + while (GlobalAlias *GA = dyn_cast(GV)) { + if (stopOnWeak && GA->mayBeOverridden()) + break; + + GV = GA->getAliasedGlobal(); - for (;;) { - GlobalValue *GV = getAliaseeGV(GA); if (!Visited.insert(GV)) return 0; - - // Iterate over aliasing chain. - GA = dyn_cast(GV); - if (!GA) - return GV; } + + return GV; } diff --git a/lib/IR/Verifier.cpp b/lib/IR/Verifier.cpp index f5c8ac623b1..50c6ae204e9 100644 --- a/lib/IR/Verifier.cpp +++ b/lib/IR/Verifier.cpp @@ -502,14 +502,10 @@ void Verifier::visitGlobalAlias(const GlobalAlias &GA) { } } Assert1(!GV->isDeclaration(), "Alias must point to a definition", &GA); - if (const GlobalAlias *GAAliasee = dyn_cast(GV)) { - Assert1(!GAAliasee->mayBeOverridden(), "Alias cannot point to a weak alias", - &GA); - } - const GlobalValue *AG = GA.getAliasedGlobal(); - Assert1(AG, "Aliasing chain should end with function or global variable", - &GA); + const GlobalValue* Resolved = GA.resolveAliasedGlobal(/*stopOnWeak*/ false); + Assert1(Resolved, + "Aliasing chain should end with function or global variable", &GA); visitGlobalValue(GA); } diff --git a/lib/Target/PowerPC/PPCAsmPrinter.cpp b/lib/Target/PowerPC/PPCAsmPrinter.cpp index 9ce8ea911cf..daf90c86ef9 100644 --- a/lib/Target/PowerPC/PPCAsmPrinter.cpp +++ b/lib/Target/PowerPC/PPCAsmPrinter.cpp @@ -381,8 +381,8 @@ void PPCAsmPrinter::EmitInstruction(const MachineInstr *MI) { if (MO.isGlobal()) { const GlobalValue *GValue = MO.getGlobal(); const GlobalAlias *GAlias = dyn_cast(GValue); - const GlobalValue *RealGValue = - GAlias ? GAlias->getAliasedGlobal() : GValue; + const GlobalValue *RealGValue = GAlias ? + GAlias->resolveAliasedGlobal(false) : GValue; MOSymbol = getSymbol(RealGValue); const GlobalVariable *GVar = dyn_cast(RealGValue); IsExternal = GVar && !GVar->hasInitializer(); @@ -428,8 +428,8 @@ void PPCAsmPrinter::EmitInstruction(const MachineInstr *MI) { else if (MO.isGlobal()) { const GlobalValue *GValue = MO.getGlobal(); const GlobalAlias *GAlias = dyn_cast(GValue); - const GlobalValue *RealGValue = - GAlias ? GAlias->getAliasedGlobal() : GValue; + const GlobalValue *RealGValue = GAlias ? + GAlias->resolveAliasedGlobal(false) : GValue; MOSymbol = getSymbol(RealGValue); const GlobalVariable *GVar = dyn_cast(RealGValue); @@ -463,8 +463,8 @@ void PPCAsmPrinter::EmitInstruction(const MachineInstr *MI) { if (MO.isGlobal()) { const GlobalValue *GValue = MO.getGlobal(); const GlobalAlias *GAlias = dyn_cast(GValue); - const GlobalValue *RealGValue = - GAlias ? GAlias->getAliasedGlobal() : GValue; + const GlobalValue *RealGValue = GAlias ? + GAlias->resolveAliasedGlobal(false) : GValue; MOSymbol = getSymbol(RealGValue); const GlobalVariable *GVar = dyn_cast(RealGValue); IsExternal = GVar && !GVar->hasInitializer(); diff --git a/lib/Target/PowerPC/PPCFastISel.cpp b/lib/Target/PowerPC/PPCFastISel.cpp index dd45683032a..4753160e091 100644 --- a/lib/Target/PowerPC/PPCFastISel.cpp +++ b/lib/Target/PowerPC/PPCFastISel.cpp @@ -1863,7 +1863,7 @@ unsigned PPCFastISel::PPCMaterializeGV(const GlobalValue *GV, MVT VT) { if (!GVar) { // If GV is an alias, use the aliasee for determining thread-locality. if (const GlobalAlias *GA = dyn_cast(GV)) - GVar = dyn_cast_or_null(GA->getAliasedGlobal()); + GVar = dyn_cast_or_null(GA->resolveAliasedGlobal(false)); } // FIXME: We don't yet handle the complexity of TLS. diff --git a/lib/Target/PowerPC/PPCISelDAGToDAG.cpp b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp index 0e75bb45757..5b09588e0f9 100644 --- a/lib/Target/PowerPC/PPCISelDAGToDAG.cpp +++ b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp @@ -1413,8 +1413,8 @@ SDNode *PPCDAGToDAGISel::Select(SDNode *N) { if (GlobalAddressSDNode *G = dyn_cast(GA)) { const GlobalValue *GValue = G->getGlobal(); const GlobalAlias *GAlias = dyn_cast(GValue); - const GlobalValue *RealGValue = - GAlias ? GAlias->getAliasedGlobal() : GValue; + const GlobalValue *RealGValue = GAlias ? + GAlias->resolveAliasedGlobal(false) : GValue; const GlobalVariable *GVar = dyn_cast(RealGValue); assert((GVar || isa(RealGValue)) && "Unexpected global value subclass!"); diff --git a/lib/Target/TargetMachine.cpp b/lib/Target/TargetMachine.cpp index fe3c870c980..f8a58ec2922 100644 --- a/lib/Target/TargetMachine.cpp +++ b/lib/Target/TargetMachine.cpp @@ -129,7 +129,7 @@ TLSModel::Model TargetMachine::getTLSModel(const GlobalValue *GV) const { // If GV is an alias then use the aliasee for determining // thread-localness. if (const GlobalAlias *GA = dyn_cast(GV)) - GV = GA->getAliasedGlobal(); + GV = GA->resolveAliasedGlobal(false); const GlobalVariable *Var = cast(GV); bool isLocal = Var->hasLocalLinkage(); diff --git a/lib/Target/X86/X86FastISel.cpp b/lib/Target/X86/X86FastISel.cpp index 9c57f0d1f19..c3e002082dd 100644 --- a/lib/Target/X86/X86FastISel.cpp +++ b/lib/Target/X86/X86FastISel.cpp @@ -363,7 +363,7 @@ bool X86FastISel::handleConstantAddresses(const Value *V, X86AddressMode &AM) { // it works...). if (const GlobalAlias *GA = dyn_cast(GV)) if (const GlobalVariable *GVar = - dyn_cast_or_null(GA->getAliasedGlobal())) + dyn_cast_or_null(GA->resolveAliasedGlobal(false))) if (GVar->isThreadLocal()) return false; diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp index 630fba01519..ec923ba7aa2 100644 --- a/lib/Target/X86/X86ISelLowering.cpp +++ b/lib/Target/X86/X86ISelLowering.cpp @@ -8509,7 +8509,7 @@ X86TargetLowering::LowerGlobalTLSAddress(SDValue Op, SelectionDAG &DAG) const { // If GV is an alias then use the aliasee for determining // thread-localness. if (const GlobalAlias *GA = dyn_cast(GV)) - GV = GA->getAliasedGlobal(); + GV = GA->resolveAliasedGlobal(false); SDLoc dl(GA); SDValue Chain = DAG.getEntryNode(); diff --git a/lib/Target/XCore/XCoreISelLowering.cpp b/lib/Target/XCore/XCoreISelLowering.cpp index 1b74013ac18..079e886457b 100644 --- a/lib/Target/XCore/XCoreISelLowering.cpp +++ b/lib/Target/XCore/XCoreISelLowering.cpp @@ -277,7 +277,7 @@ getGlobalAddressWrapper(SDValue GA, const GlobalValue *GV, const GlobalValue *UnderlyingGV = GV; // If GV is an alias then use the aliasee to determine the wrapper type if (const GlobalAlias *GA = dyn_cast(GV)) - UnderlyingGV = GA->getAliasedGlobal(); + UnderlyingGV = GA->resolveAliasedGlobal(); if (const GlobalVariable *GVar = dyn_cast(UnderlyingGV)) { if ( ( GVar->isConstant() && UnderlyingGV->isLocalLinkage(GV->getLinkage()) ) diff --git a/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp b/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp index df1549d405c..0249df1c6d8 100644 --- a/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp +++ b/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp @@ -554,7 +554,8 @@ bool DataFlowSanitizer::runOnModule(Module &M) { ++i; // Don't stop on weak. We assume people aren't playing games with the // instrumentedness of overridden weak aliases. - if (Function *F = dyn_cast(GA->getAliasedGlobal())) { + if (Function *F = dyn_cast( + GA->resolveAliasedGlobal(/*stopOnWeak=*/false))) { bool GAInst = isInstrumented(GA), FInst = isInstrumented(F); if (GAInst && FInst) { addGlobalNamePrefix(GA); diff --git a/test/CodeGen/X86/dllexport-x86_64.ll b/test/CodeGen/X86/dllexport-x86_64.ll index a38c2d8f8ab..1fadfec2543 100644 --- a/test/CodeGen/X86/dllexport-x86_64.ll +++ b/test/CodeGen/X86/dllexport-x86_64.ll @@ -65,7 +65,7 @@ define weak_odr dllexport void @weak1() { @alias2 = dllexport alias void()* @f1 ; CHECK: .globl alias3 -; CHECK: alias3 = notExported +; CHECK: alias3 = alias @alias3 = dllexport alias void()* @alias ; CHECK: .weak weak_alias diff --git a/test/CodeGen/X86/dllexport.ll b/test/CodeGen/X86/dllexport.ll index 1b34d238693..7f0dadb6a2e 100644 --- a/test/CodeGen/X86/dllexport.ll +++ b/test/CodeGen/X86/dllexport.ll @@ -80,7 +80,7 @@ define weak_odr dllexport void @weak1() { @alias2 = dllexport alias void()* @f1 ; CHECK: .globl _alias3 -; CHECK: _alias3 = _notExported +; CHECK: _alias3 = _alias @alias3 = dllexport alias void()* @alias ; CHECK: .weak _weak_alias diff --git a/test/Feature/aliases.ll b/test/Feature/aliases.ll index 7fe9d0b374e..7ffa5f26013 100644 --- a/test/Feature/aliases.ll +++ b/test/Feature/aliases.ll @@ -14,7 +14,7 @@ define i32 @foo_f() { ret i32 0 } -@bar_f = alias weak_odr %FunTy* @foo_f +@bar_f = alias weak %FunTy* @foo_f @bar_ff = alias i32()* @bar_f @bar_i = alias internal i32* @bar diff --git a/test/Transforms/GlobalOpt/alias-resolve.ll b/test/Transforms/GlobalOpt/alias-resolve.ll index 2d5a956d14b..64e3d88af8a 100644 --- a/test/Transforms/GlobalOpt/alias-resolve.ll +++ b/test/Transforms/GlobalOpt/alias-resolve.ll @@ -1,17 +1,14 @@ ; RUN: opt < %s -globalopt -S | FileCheck %s @foo1 = alias void ()* @foo2 -; CHECK: @foo1 = alias void ()* @bar2 +; CHECK: @foo1 = alias void ()* @foo2 -@foo2 = alias void()* @bar1 -; CHECK: @foo2 = alias void ()* @bar2 +@foo2 = alias weak void()* @bar1 +; CHECK: @foo2 = alias weak void ()* @bar2 @bar1 = alias void ()* @bar2 ; CHECK: @bar1 = alias void ()* @bar2 -@weak1 = alias weak void ()* @bar2 -; CHECK: @weak1 = alias weak void ()* @bar2 - define void @bar2() { ret void } @@ -20,16 +17,14 @@ define void @bar2() { define void @baz() { entry: call void @foo1() -; CHECK: call void @bar2() +; CHECK: call void @foo2() call void @foo2() -; CHECK: call void @bar2() +; CHECK: call void @foo2() call void @bar1() ; CHECK: call void @bar2() - call void @weak1() -; CHECK: call void @weak1() ret void } -- 2.34.1