/// emitAssembly - Print the frametable. The ocaml frametable format is thus: /// /// extern "C" struct align(sizeof(intptr_t)) { /// uint16_t NumDescriptors; /// struct align(sizeof(intptr_t)) { /// void *ReturnAddress; /// uint16_t FrameSize; /// uint16_t NumLiveOffsets; /// uint16_t LiveOffsets[NumLiveOffsets]; /// } Descriptors[NumDescriptors]; /// } caml${module}__frametable; /// /// Note that this precludes programs from stack frames larger than 64K /// (FrameSize and LiveOffsets would overflow). FrameTablePrinter will abort if /// either condition is detected in a function which uses the GC. /// void OcamlGCMetadataPrinter::finishAssembly(AsmPrinter &AP) { unsigned IntPtrSize = AP.TM.getTargetData()->getPointerSize(); AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getTextSection()); EmitCamlGlobal(getModule(), AP, "code_end"); AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getDataSection()); EmitCamlGlobal(getModule(), AP, "data_end"); // FIXME: Why does ocaml emit this?? AP.OutStreamer.EmitIntValue(0, IntPtrSize, 0); AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getDataSection()); EmitCamlGlobal(getModule(), AP, "frametable"); for (iterator I = begin(), IE = end(); I != IE; ++I) { GCFunctionInfo &FI = **I; uint64_t FrameSize = FI.getFrameSize(); if (FrameSize >= 1<<16) { // Very rude! report_fatal_error("Function '" + FI.getFunction().getName() + "' is too large for the ocaml GC! " "Frame size " + Twine(FrameSize) + ">= 65536.\n" "(" + Twine(uintptr_t(&FI)) + ")"); } AP.OutStreamer.AddComment("live roots for " + Twine(FI.getFunction().getName())); AP.OutStreamer.AddBlankLine(); for (GCFunctionInfo::iterator J = FI.begin(), JE = FI.end(); J != JE; ++J) { size_t LiveCount = FI.live_size(J); if (LiveCount >= 1<<16) { // Very rude! report_fatal_error("Function '" + FI.getFunction().getName() + "' is too large for the ocaml GC! " "Live root count "+Twine(LiveCount)+" >= 65536."); } AP.OutStreamer.EmitSymbolValue(J->Label, IntPtrSize, 0); AP.EmitInt16(FrameSize); AP.EmitInt16(LiveCount); for (GCFunctionInfo::live_iterator K = FI.live_begin(J), KE = FI.live_end(J); K != KE; ++K) { assert(K->StackOffset < 1<<16 && "GC root stack offset is outside of fixed stack frame and out " "of range for ocaml GC!"); AP.EmitInt32(K->StackOffset); } AP.EmitAlignment(IntPtrSize == 4 ? 2 : 3); } } }
void RgcPrinter::finishAssembly(Module &M, GCModuleInfo &Info, AsmPrinter &AP) { MCStreamer &OS = AP.OutStreamer; unsigned IntPtrSize = AP.TM.getSubtargetImpl()->getDataLayout()->getPointerSize(); // Put this in the data section. OS.SwitchSection(AP.getObjFileLowering().getDataSection()); // For each function... for (GCModuleInfo::FuncInfoVec::iterator FI = Info.funcinfo_begin(), FE = Info.funcinfo_end(); FI != FE; ++FI) { GCFunctionInfo &MD = **FI; // A compact GC layout. Emit this data structure: // // struct { // int32_t PointCount; // void *SafePointAddress[PointCount]; // int32_t StackFrameSize; // in words // int32_t StackArity; // int32_t LiveCount; // int32_t LiveOffsets[LiveCount]; // } __gcmap_<FUNCTIONNAME>; // Align to address width. // AP.EmitAlignment(IntPtrSize == 4 ? 2 : 3); // Emit PointCount. OS.AddComment("safe point count"); AP.EmitInt32(MD.size()); // And each safe point... for (GCFunctionInfo::iterator PI = MD.begin(), PE = MD.end(); PI != PE; ++PI) { // Emit the address of the safe point. OS.AddComment("safe point address"); MCSymbol *Label = PI->Label; AP.EmitLabelPlusOffset(Label/*Hi*/, 0/*Offset*/, 4/*Size*/); } // Stack information never change in safe points! Only print info from the // first call-site. GCFunctionInfo::iterator PI = MD.begin(); // Emit the stack frame size. OS.AddComment("stack frame size (in words)"); AP.EmitInt32(MD.getFrameSize() / IntPtrSize); // Emit stack arity, i.e. the number of stacked arguments. unsigned RegisteredArgs = IntPtrSize == 4 ? 5 : 6; unsigned StackArity = MD.getFunction().arg_size() > RegisteredArgs ? MD.getFunction().arg_size() - RegisteredArgs : 0; OS.AddComment("stack arity"); AP.EmitInt32(StackArity); // Emit the number of live roots in the function. OS.AddComment("live root count"); AP.EmitInt32(MD.live_size(PI)); // And for each live root... for (GCFunctionInfo::live_iterator LI = MD.live_begin(PI), LE = MD.live_end(PI); LI != LE; ++LI) { // Emit live root's offset within the stack frame. OS.AddComment("stack index (offset / wordsize)"); AP.EmitInt32(LI->StackOffset); } } }