1 //===-- OcamlGCPrinter.cpp - Ocaml frametable emitter ---------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file implements printing the assembly code for an Ocaml frametable. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "llvm/CodeGen/GCs.h" 15 #include "llvm/ADT/SmallString.h" 16 #include "llvm/CodeGen/AsmPrinter.h" 17 #include "llvm/CodeGen/GCMetadataPrinter.h" 18 #include "llvm/IR/DataLayout.h" 19 #include "llvm/IR/Mangler.h" 20 #include "llvm/IR/Module.h" 21 #include "llvm/MC/MCAsmInfo.h" 22 #include "llvm/MC/MCContext.h" 23 #include "llvm/MC/MCStreamer.h" 24 #include "llvm/MC/MCSymbol.h" 25 #include "llvm/Support/ErrorHandling.h" 26 #include "llvm/Support/FormattedStream.h" 27 #include "llvm/Target/TargetLoweringObjectFile.h" 28 #include "llvm/Target/TargetMachine.h" 29 #include "llvm/Target/TargetSubtargetInfo.h" 30 #include <cctype> 31 using namespace llvm; 32 33 namespace { 34 35 class OcamlGCMetadataPrinter : public GCMetadataPrinter { 36 public: 37 void beginAssembly(Module &M, GCModuleInfo &Info, AsmPrinter &AP) override; 38 void finishAssembly(Module &M, GCModuleInfo &Info, AsmPrinter &AP) override; 39 }; 40 } 41 42 static GCMetadataPrinterRegistry::Add<OcamlGCMetadataPrinter> 43 Y("ocaml", "ocaml 3.10-compatible collector"); 44 45 void llvm::linkOcamlGCPrinter() {} 46 47 static void EmitCamlGlobal(const Module &M, AsmPrinter &AP, const char *Id) { 48 const std::string &MId = M.getModuleIdentifier(); 49 50 std::string SymName; 51 SymName += "caml"; 52 size_t Letter = SymName.size(); 53 SymName.append(MId.begin(), std::find(MId.begin(), MId.end(), '.')); 54 SymName += "__"; 55 SymName += Id; 56 57 // Capitalize the first letter of the module name. 58 SymName[Letter] = toupper(SymName[Letter]); 59 60 SmallString<128> TmpStr; 61 Mangler::getNameWithPrefix(TmpStr, SymName, M.getDataLayout()); 62 63 MCSymbol *Sym = AP.OutContext.getOrCreateSymbol(TmpStr); 64 65 AP.OutStreamer->EmitSymbolAttribute(Sym, MCSA_Global); 66 AP.OutStreamer->EmitLabel(Sym); 67 } 68 69 void OcamlGCMetadataPrinter::beginAssembly(Module &M, GCModuleInfo &Info, 70 AsmPrinter &AP) { 71 AP.OutStreamer->SwitchSection(AP.getObjFileLowering().getTextSection()); 72 EmitCamlGlobal(M, AP, "code_begin"); 73 74 AP.OutStreamer->SwitchSection(AP.getObjFileLowering().getDataSection()); 75 EmitCamlGlobal(M, AP, "data_begin"); 76 } 77 78 /// emitAssembly - Print the frametable. The ocaml frametable format is thus: 79 /// 80 /// extern "C" struct align(sizeof(intptr_t)) { 81 /// uint16_t NumDescriptors; 82 /// struct align(sizeof(intptr_t)) { 83 /// void *ReturnAddress; 84 /// uint16_t FrameSize; 85 /// uint16_t NumLiveOffsets; 86 /// uint16_t LiveOffsets[NumLiveOffsets]; 87 /// } Descriptors[NumDescriptors]; 88 /// } caml${module}__frametable; 89 /// 90 /// Note that this precludes programs from stack frames larger than 64K 91 /// (FrameSize and LiveOffsets would overflow). FrameTablePrinter will abort if 92 /// either condition is detected in a function which uses the GC. 93 /// 94 void OcamlGCMetadataPrinter::finishAssembly(Module &M, GCModuleInfo &Info, 95 AsmPrinter &AP) { 96 unsigned IntPtrSize = M.getDataLayout().getPointerSize(); 97 98 AP.OutStreamer->SwitchSection(AP.getObjFileLowering().getTextSection()); 99 EmitCamlGlobal(M, AP, "code_end"); 100 101 AP.OutStreamer->SwitchSection(AP.getObjFileLowering().getDataSection()); 102 EmitCamlGlobal(M, AP, "data_end"); 103 104 // FIXME: Why does ocaml emit this?? 105 AP.OutStreamer->EmitIntValue(0, IntPtrSize); 106 107 AP.OutStreamer->SwitchSection(AP.getObjFileLowering().getDataSection()); 108 EmitCamlGlobal(M, AP, "frametable"); 109 110 int NumDescriptors = 0; 111 for (GCModuleInfo::FuncInfoVec::iterator I = Info.funcinfo_begin(), 112 IE = Info.funcinfo_end(); 113 I != IE; ++I) { 114 GCFunctionInfo &FI = **I; 115 if (FI.getStrategy().getName() != getStrategy().getName()) 116 // this function is managed by some other GC 117 continue; 118 for (GCFunctionInfo::iterator J = FI.begin(), JE = FI.end(); J != JE; ++J) { 119 NumDescriptors++; 120 } 121 } 122 123 if (NumDescriptors >= 1 << 16) { 124 // Very rude! 125 report_fatal_error(" Too much descriptor for ocaml GC"); 126 } 127 AP.EmitInt16(NumDescriptors); 128 AP.EmitAlignment(IntPtrSize == 4 ? 2 : 3); 129 130 for (GCModuleInfo::FuncInfoVec::iterator I = Info.funcinfo_begin(), 131 IE = Info.funcinfo_end(); 132 I != IE; ++I) { 133 GCFunctionInfo &FI = **I; 134 if (FI.getStrategy().getName() != getStrategy().getName()) 135 // this function is managed by some other GC 136 continue; 137 138 uint64_t FrameSize = FI.getFrameSize(); 139 if (FrameSize >= 1 << 16) { 140 // Very rude! 141 report_fatal_error("Function '" + FI.getFunction().getName() + 142 "' is too large for the ocaml GC! " 143 "Frame size " + 144 Twine(FrameSize) + ">= 65536.\n" 145 "(" + 146 Twine(uintptr_t(&FI)) + ")"); 147 } 148 149 AP.OutStreamer->AddComment("live roots for " + 150 Twine(FI.getFunction().getName())); 151 AP.OutStreamer->AddBlankLine(); 152 153 for (GCFunctionInfo::iterator J = FI.begin(), JE = FI.end(); J != JE; ++J) { 154 size_t LiveCount = FI.live_size(J); 155 if (LiveCount >= 1 << 16) { 156 // Very rude! 157 report_fatal_error("Function '" + FI.getFunction().getName() + 158 "' is too large for the ocaml GC! " 159 "Live root count " + 160 Twine(LiveCount) + " >= 65536."); 161 } 162 163 AP.OutStreamer->EmitSymbolValue(J->Label, IntPtrSize); 164 AP.EmitInt16(FrameSize); 165 AP.EmitInt16(LiveCount); 166 167 for (GCFunctionInfo::live_iterator K = FI.live_begin(J), 168 KE = FI.live_end(J); 169 K != KE; ++K) { 170 if (K->StackOffset >= 1 << 16) { 171 // Very rude! 172 report_fatal_error( 173 "GC root stack offset is outside of fixed stack frame and out " 174 "of range for ocaml GC!"); 175 } 176 AP.EmitInt16(K->StackOffset); 177 } 178 179 AP.EmitAlignment(IntPtrSize == 4 ? 2 : 3); 180 } 181 } 182 } 183
