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/CodeGen/AsmPrinter.h" 16 #include "llvm/CodeGen/GCMetadataPrinter.h" 17 #include "llvm/Module.h" 18 #include "llvm/MC/MCAsmInfo.h" 19 #include "llvm/MC/MCContext.h" 20 #include "llvm/MC/MCSymbol.h" 21 #include "llvm/MC/MCStreamer.h" 22 #include "llvm/Target/Mangler.h" 23 #include "llvm/Target/TargetData.h" 24 #include "llvm/Target/TargetLoweringObjectFile.h" 25 #include "llvm/Target/TargetMachine.h" 26 #include "llvm/ADT/SmallString.h" 27 #include "llvm/Support/ErrorHandling.h" 28 #include "llvm/Support/FormattedStream.h" 29 #include <cctype> 30 using namespace llvm; 31 32 namespace { 33 34 class OcamlGCMetadataPrinter : public GCMetadataPrinter { 35 public: 36 void beginAssembly(AsmPrinter &AP); 37 void finishAssembly(AsmPrinter &AP); 38 }; 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 AP.Mang->getNameWithPrefix(TmpStr, SymName); 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(AsmPrinter &AP) { 70 AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getTextSection()); 71 EmitCamlGlobal(getModule(), AP, "code_begin"); 72 73 AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getDataSection()); 74 EmitCamlGlobal(getModule(), AP, "data_begin"); 75 } 76 77 /// emitAssembly - Print the frametable. The ocaml frametable format is thus: 78 /// 79 /// extern "C" struct align(sizeof(intptr_t)) { 80 /// uint16_t NumDescriptors; 81 /// struct align(sizeof(intptr_t)) { 82 /// void *ReturnAddress; 83 /// uint16_t FrameSize; 84 /// uint16_t NumLiveOffsets; 85 /// uint16_t LiveOffsets[NumLiveOffsets]; 86 /// } Descriptors[NumDescriptors]; 87 /// } caml${module}__frametable; 88 /// 89 /// Note that this precludes programs from stack frames larger than 64K 90 /// (FrameSize and LiveOffsets would overflow). FrameTablePrinter will abort if 91 /// either condition is detected in a function which uses the GC. 92 /// 93 void OcamlGCMetadataPrinter::finishAssembly(AsmPrinter &AP) { 94 unsigned IntPtrSize = AP.TM.getTargetData()->getPointerSize(); 95 96 AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getTextSection()); 97 EmitCamlGlobal(getModule(), AP, "code_end"); 98 99 AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getDataSection()); 100 EmitCamlGlobal(getModule(), AP, "data_end"); 101 102 // FIXME: Why does ocaml emit this?? 103 AP.OutStreamer.EmitIntValue(0, IntPtrSize, 0); 104 105 AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getDataSection()); 106 EmitCamlGlobal(getModule(), AP, "frametable"); 107 108 int NumDescriptors = 0; 109 for (iterator I = begin(), IE = end(); I != IE; ++I) { 110 GCFunctionInfo &FI = **I; 111 for (GCFunctionInfo::iterator J = FI.begin(), JE = FI.end(); J != JE; ++J) { 112 NumDescriptors++; 113 } 114 } 115 116 if (NumDescriptors >= 1<<16) { 117 // Very rude! 118 report_fatal_error(" Too much descriptor for ocaml GC"); 119 } 120 AP.EmitInt16(NumDescriptors); 121 AP.EmitAlignment(IntPtrSize == 4 ? 2 : 3); 122 123 for (iterator I = begin(), IE = end(); I != IE; ++I) { 124 GCFunctionInfo &FI = **I; 125 126 uint64_t FrameSize = FI.getFrameSize(); 127 if (FrameSize >= 1<<16) { 128 // Very rude! 129 report_fatal_error("Function '" + FI.getFunction().getName() + 130 "' is too large for the ocaml GC! " 131 "Frame size " + Twine(FrameSize) + ">= 65536.\n" 132 "(" + Twine(uintptr_t(&FI)) + ")"); 133 } 134 135 AP.OutStreamer.AddComment("live roots for " + 136 Twine(FI.getFunction().getName())); 137 AP.OutStreamer.AddBlankLine(); 138 139 for (GCFunctionInfo::iterator J = FI.begin(), JE = FI.end(); J != JE; ++J) { 140 size_t LiveCount = FI.live_size(J); 141 if (LiveCount >= 1<<16) { 142 // Very rude! 143 report_fatal_error("Function '" + FI.getFunction().getName() + 144 "' is too large for the ocaml GC! " 145 "Live root count "+Twine(LiveCount)+" >= 65536."); 146 } 147 148 AP.OutStreamer.EmitSymbolValue(J->Label, IntPtrSize, 0); 149 AP.EmitInt16(FrameSize); 150 AP.EmitInt16(LiveCount); 151 152 for (GCFunctionInfo::live_iterator K = FI.live_begin(J), 153 KE = FI.live_end(J); K != KE; ++K) { 154 if (K->StackOffset >= 1<<16) { 155 // Very rude! 156 report_fatal_error( 157 "GC root stack offset is outside of fixed stack frame and out " 158 "of range for ocaml GC!"); 159 } 160 AP.EmitInt16(K->StackOffset); 161 } 162 163 AP.EmitAlignment(IntPtrSize == 4 ? 2 : 3); 164 } 165 } 166 } 167
