From: Keno Fischer Date: Tue, 14 Jul 2015 19:22:51 +0000 (+0000) Subject: [CodeGen] Force emission of personality directive if explicitly specified X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=890c16626f63ca0978b705e173ed9e5a0068d418;p=oota-llvm.git [CodeGen] Force emission of personality directive if explicitly specified Summary: Before this change, personality directives were not emitted if there was no invoke left in the function (of course until recently this also meant that we couldn't know what the personality actually was). This patch forces personality directives to still be emitted, unless it is known to be a noop in the absence of invokes, or the user explicitly specified `nounwind` (and not `uwtable`) on the function. Reviewers: majnemer, rnk Subscribers: rnk, llvm-commits Differential Revision: http://reviews.llvm.org/D10884 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242185 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/include/llvm/Analysis/LibCallSemantics.h b/include/llvm/Analysis/LibCallSemantics.h index 170e2a49a8e..b4bef310e59 100644 --- a/include/llvm/Analysis/LibCallSemantics.h +++ b/include/llvm/Analysis/LibCallSemantics.h @@ -206,6 +206,18 @@ class InvokeInst; llvm_unreachable("invalid enum"); } + /// \brief Return true if this personality may be safely removed if there + /// are no invoke instructions remaining in the current function. + inline bool isNoOpWithoutInvoke(EHPersonality Pers) { + switch (Pers) { + case EHPersonality::Unknown: + return false; + // All known personalities currently have this behavior + default: return true; + } + llvm_unreachable("invalid enum"); + } + bool canSimplifyInvokeNoUnwind(const Function *F); } // end namespace llvm diff --git a/include/llvm/CodeGen/MachineModuleInfo.h b/include/llvm/CodeGen/MachineModuleInfo.h index ccaa83a238a..4cdfe2463c9 100644 --- a/include/llvm/CodeGen/MachineModuleInfo.h +++ b/include/llvm/CodeGen/MachineModuleInfo.h @@ -320,6 +320,7 @@ public: /// information. void addPersonality(MachineBasicBlock *LandingPad, const Function *Personality); + void addPersonality(const Function *Personality); void addWinEHState(MachineBasicBlock *LandingPad, int State); diff --git a/lib/CodeGen/AsmPrinter/ARMException.cpp b/lib/CodeGen/AsmPrinter/ARMException.cpp index 4cb460a7bbf..0bad7954b98 100644 --- a/lib/CodeGen/AsmPrinter/ARMException.cpp +++ b/lib/CodeGen/AsmPrinter/ARMException.cpp @@ -69,24 +69,32 @@ void ARMException::beginFunction(const MachineFunction *MF) { /// void ARMException::endFunction(const MachineFunction *MF) { ARMTargetStreamer &ATS = getTargetStreamer(); + const Function *F = MF->getFunction(); + const Function *Per = nullptr; + if (F->hasPersonalityFn()) + Per = dyn_cast(F->getPersonalityFn()->stripPointerCasts()); + assert(!MMI->getPersonality() || Per == MMI->getPersonality()); + bool forceEmitPersonality = + F->hasPersonalityFn() && !isNoOpWithoutInvoke(classifyEHPersonality(Per)) && + F->needsUnwindTableEntry(); + bool shouldEmitPersonality = forceEmitPersonality || + !MMI->getLandingPads().empty(); if (!Asm->MF->getFunction()->needsUnwindTableEntry() && - MMI->getLandingPads().empty()) + !shouldEmitPersonality) ATS.emitCantUnwind(); - else { - if (!MMI->getLandingPads().empty()) { - // Emit references to personality. - if (const Function *Personality = MMI->getPersonality()) { - MCSymbol *PerSym = Asm->getSymbol(Personality); - Asm->OutStreamer->EmitSymbolAttribute(PerSym, MCSA_Global); - ATS.emitPersonality(PerSym); - } - - // Emit .handlerdata directive. - ATS.emitHandlerData(); - - // Emit actual exception table - emitExceptionTable(); + else if (shouldEmitPersonality) { + // Emit references to personality. + if (Per) { + MCSymbol *PerSym = Asm->getSymbol(Per); + Asm->OutStreamer->EmitSymbolAttribute(PerSym, MCSA_Global); + ATS.emitPersonality(PerSym); } + + // Emit .handlerdata directive. + ATS.emitHandlerData(); + + // Emit actual exception table + emitExceptionTable(); } if (Asm->MAI->getExceptionHandlingType() == ExceptionHandling::ARM) diff --git a/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp b/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp index 0bc873e326b..2c212c7ecee 100644 --- a/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp +++ b/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp @@ -89,6 +89,7 @@ void DwarfCFIException::endModule() { void DwarfCFIException::beginFunction(const MachineFunction *MF) { shouldEmitMoves = shouldEmitPersonality = shouldEmitLSDA = false; + const Function *F = MF->getFunction(); // If any landing pads survive, we need an EH table. bool hasLandingPads = !MMI->getLandingPads().empty(); @@ -104,10 +105,24 @@ void DwarfCFIException::beginFunction(const MachineFunction *MF) { const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering(); unsigned PerEncoding = TLOF.getPersonalityEncoding(); - const Function *Per = MMI->getPersonality(); - - shouldEmitPersonality = hasLandingPads && - PerEncoding != dwarf::DW_EH_PE_omit && Per; + const Function *Per = nullptr; + if (F->hasPersonalityFn()) + Per = dyn_cast(F->getPersonalityFn()->stripPointerCasts()); + assert(!MMI->getPersonality() || Per == MMI->getPersonality()); + + // Emit a personality function even when there are no landing pads + bool forceEmitPersonality = + // ...if a personality function is explicitly specified + F->hasPersonalityFn() && + // ... and it's not known to be a noop in the absence of invokes + !isNoOpWithoutInvoke(classifyEHPersonality(Per)) && + // ... and we're not explicitly asked not to emit it + F->needsUnwindTableEntry(); + + shouldEmitPersonality = + (forceEmitPersonality || + (hasLandingPads && PerEncoding != dwarf::DW_EH_PE_omit)) && + Per; unsigned LSDAEncoding = TLOF.getLSDAEncoding(); shouldEmitLSDA = shouldEmitPersonality && @@ -123,6 +138,11 @@ void DwarfCFIException::beginFunction(const MachineFunction *MF) { if (!shouldEmitPersonality) return; + // If we are forced to emit this personality, make sure to record + // it because it might not appear in any landingpad + if (forceEmitPersonality) + MMI->addPersonality(Per); + const MCSymbol *Sym = TLOF.getCFIPersonalitySymbol(Per, *Asm->Mang, Asm->TM, MMI); Asm->OutStreamer->EmitCFIPersonality(Sym, PerEncoding); diff --git a/lib/CodeGen/AsmPrinter/EHStreamer.cpp b/lib/CodeGen/AsmPrinter/EHStreamer.cpp index 1be3fd74d60..49ef8d3ddc8 100644 --- a/lib/CodeGen/AsmPrinter/EHStreamer.cpp +++ b/lib/CodeGen/AsmPrinter/EHStreamer.cpp @@ -309,7 +309,7 @@ computeCallSiteTable(SmallVectorImpl &CallSites, // If some instruction between the previous try-range and the end of the // function may throw, create a call-site entry with no landing pad for the // region following the try-range. - if (SawPotentiallyThrowing && !IsSJLJ) { + if (SawPotentiallyThrowing && !IsSJLJ && LastLabel != nullptr) { CallSiteEntry Site = { LastLabel, nullptr, nullptr, 0 }; CallSites.push_back(Site); } diff --git a/lib/CodeGen/AsmPrinter/WinException.cpp b/lib/CodeGen/AsmPrinter/WinException.cpp index 7ef2832d41a..71c77815e28 100644 --- a/lib/CodeGen/AsmPrinter/WinException.cpp +++ b/lib/CodeGen/AsmPrinter/WinException.cpp @@ -74,8 +74,12 @@ void WinException::beginFunction(const MachineFunction *MF) { if (F->hasPersonalityFn()) Per = dyn_cast(F->getPersonalityFn()->stripPointerCasts()); - shouldEmitPersonality = hasLandingPads && - PerEncoding != dwarf::DW_EH_PE_omit && Per; + bool forceEmitPersonality = + F->hasPersonalityFn() && !isNoOpWithoutInvoke(classifyEHPersonality(Per)) && + F->needsUnwindTableEntry(); + + shouldEmitPersonality = forceEmitPersonality || (hasLandingPads && + PerEncoding != dwarf::DW_EH_PE_omit && Per); unsigned LSDAEncoding = TLOF.getLSDAEncoding(); shouldEmitLSDA = shouldEmitPersonality && diff --git a/lib/CodeGen/MachineModuleInfo.cpp b/lib/CodeGen/MachineModuleInfo.cpp index 42d0603ab96..6a206249d83 100644 --- a/lib/CodeGen/MachineModuleInfo.cpp +++ b/lib/CodeGen/MachineModuleInfo.cpp @@ -320,7 +320,10 @@ void MachineModuleInfo::addPersonality(MachineBasicBlock *LandingPad, const Function *Personality) { LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad); LP.Personality = Personality; + addPersonality(Personality); +} +void MachineModuleInfo::addPersonality(const Function *Personality) { for (unsigned i = 0; i < Personalities.size(); ++i) if (Personalities[i] == Personality) return; diff --git a/test/CodeGen/X86/eh-nolandingpads.ll b/test/CodeGen/X86/eh-nolandingpads.ll new file mode 100644 index 00000000000..96295226621 --- /dev/null +++ b/test/CodeGen/X86/eh-nolandingpads.ll @@ -0,0 +1,12 @@ +; RUN: llc < %s -mtriple=x86_64-pc-linux | FileCheck %s +; Test that we emit functions with explicitly specified personality, +; even if no landing pads are left. + +declare i32 @__my_personality_v0(...) +declare void @might_throw() + +define i32 @foo() personality i32 (...)* @__my_personality_v0 { +; CHECK: .cfi_personality 3, __my_personality_v0 + call void @might_throw() + ret i32 0 +}