C++ AsmPrinter::EmitAlignment方法代码示例

/// 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 ErlangGCPrinter::finishAssembly(Module &M, GCModuleInfo &Info,
                                     AsmPrinter &AP) {
  MCStreamer &OS = *AP.OutStreamer;
  unsigned IntPtrSize = M.getDataLayout().getPointerSize();

  // Put this in a custom .note section.
  OS.SwitchSection(
      AP.getObjFileLowering().getContext().getELFSection(".note.gc",
                                                         ELF::SHT_PROGBITS, 0));

  // For each function...
  for (GCModuleInfo::FuncInfoVec::iterator FI = Info.funcinfo_begin(),
                                           IE = Info.funcinfo_end();
       FI != IE; ++FI) {
    GCFunctionInfo &MD = **FI;
    if (MD.getStrategy().getName() != getStrategy().getName())
      // this function is managed by some other GC
      continue;
    /** A compact GC layout. Emit this data structure:
     *
     * struct {
     *   int16_t PointCount;
     *   void *SafePointAddress[PointCount];
     *   int16_t StackFrameSize; (in words)
     *   int16_t StackArity;
     *   int16_t LiveCount;
     *   int16_t LiveOffsets[LiveCount];
     * } __gcmap_<FUNCTIONNAME>;
     **/

    // Align to address width.
    AP.EmitAlignment(IntPtrSize == 4 ? 2 : 3);

    // Emit PointCount.
    OS.AddComment("safe point count");
    AP.EmitInt16(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.EmitInt16(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.EmitInt16(StackArity);

    // Emit the number of live roots in the function.
    OS.AddComment("live root count");
    AP.EmitInt16(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.EmitInt16(LI->StackOffset / IntPtrSize);
    }
  }
}

/// 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");

  int NumDescriptors = 0;
  for (iterator I = begin(), IE = end(); I != IE; ++I) {
    GCFunctionInfo &FI = **I;
    for (GCFunctionInfo::iterator J = FI.begin(), JE = FI.end(); J != JE; ++J) {
      NumDescriptors++;
    }
  }

  if (NumDescriptors >= 1<<16) {
    // Very rude!
    report_fatal_error(" Too much descriptor for ocaml GC");
  }
  AP.EmitInt16(NumDescriptors);
  AP.EmitAlignment(IntPtrSize == 4 ? 2 : 3);

  const MCRegisterInfo &MRI = AP.OutStreamer.getContext().getRegisterInfo();

  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 (unsigned PI = 0, PE = FI.size(); PI != PE; ++PI) {
      size_t LiveCount = FI.live_size(PI);
      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.");
      }

      GCPoint &Point = FI.getPoint(PI);
      AP.OutStreamer.EmitSymbolValue(Point.Label, IntPtrSize, 0);
      AP.EmitInt16(FrameSize);
      AP.EmitInt16(LiveCount);

      for (GCFunctionInfo::live_iterator K = FI.live_begin(PI),
                                         KE = FI.live_end(PI); K != KE; ++K) {
        if (K->isReg()) {
          AP.OutStreamer.AddComment("register root at " +
                                    Twine(MRI.getName(K->Loc.PhysReg)));
          AP.OutStreamer.AddBlankLine();
          continue;
        }
        if (K->Loc.StackOffset >= 1<<16) {
          // Very rude!
          report_fatal_error(
                 "GC root stack offset is outside of fixed stack frame and out "
                 "of range for ocaml GC!");
        }
        AP.EmitInt16(K->Loc.StackOffset);
      }

      AP.EmitAlignment(IntPtrSize == 4 ? 2 : 3);
    }
  }
}

/// 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(Module &M, GCModuleInfo &Info,
                                            AsmPrinter &AP) {
  unsigned IntPtrSize = M.getDataLayout().getPointerSize();

  AP.OutStreamer->SwitchSection(AP.getObjFileLowering().getTextSection());
  EmitCamlGlobal(M, AP, "code_end");

  AP.OutStreamer->SwitchSection(AP.getObjFileLowering().getDataSection());
  EmitCamlGlobal(M, AP, "data_end");

  // FIXME: Why does ocaml emit this??
  AP.OutStreamer->EmitIntValue(0, IntPtrSize);

  AP.OutStreamer->SwitchSection(AP.getObjFileLowering().getDataSection());
  EmitCamlGlobal(M, AP, "frametable");

  int NumDescriptors = 0;
  for (GCModuleInfo::FuncInfoVec::iterator I = Info.funcinfo_begin(),
                                           IE = Info.funcinfo_end();
       I != IE; ++I) {
    GCFunctionInfo &FI = **I;
    if (FI.getStrategy().getName() != getStrategy().getName())
      // this function is managed by some other GC
      continue;
    for (GCFunctionInfo::iterator J = FI.begin(), JE = FI.end(); J != JE; ++J) {
      NumDescriptors++;
    }
  }

  if (NumDescriptors >= 1 << 16) {
    // Very rude!
    report_fatal_error(" Too much descriptor for ocaml GC");
  }
  AP.emitInt16(NumDescriptors);
  AP.EmitAlignment(IntPtrSize == 4 ? 2 : 3);

  for (GCModuleInfo::FuncInfoVec::iterator I = Info.funcinfo_begin(),
                                           IE = Info.funcinfo_end();
       I != IE; ++I) {
    GCFunctionInfo &FI = **I;
    if (FI.getStrategy().getName() != getStrategy().getName())
      // this function is managed by some other GC
      continue;

    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);
      AP.emitInt16(FrameSize);
      AP.emitInt16(LiveCount);

      for (GCFunctionInfo::live_iterator K = FI.live_begin(J),
                                         KE = FI.live_end(J);
           K != KE; ++K) {
        if (K->StackOffset >= 1 << 16) {
          // Very rude!
          report_fatal_error(
              "GC root stack offset is outside of fixed stack frame and out "
              "of range for ocaml GC!");
        }
        AP.emitInt16(K->StackOffset);
      }
//.........这里部分代码省略.........

//.........这里部分代码省略.........
                            }
                        }
                    }
                } else {
                    // No metadata, so it's an object reference - just add the field offset.
                    fieldOffsets.push_back(offset);
                }
            }

            // Nothing to trace? Then we're done.
            if (fieldOffsets.empty() && traceMethods.empty()) {
                continue;
            }

            // Create a folding set node and merge with any identical trace tables.
            std::sort(fieldOffsets.begin(), fieldOffsets.end());
            llvm::FoldingSetNodeID id;
            StackTraceTable::ProfileEntries(id, fieldOffsets, traceMethods);

            void * insertPos;
            StackTraceTable * sTable = traceTables.FindNodeOrInsertPos(id, insertPos);
            if (sTable == NULL) {
                sTable = new StackTraceTable(fieldOffsets, traceMethods);

                // Generate the labels for the trace table and field offset table.
                sTable->fieldOffsetsLabel = AP.GetTempSymbol("gc_stack_offsets", nextLabel);
                sTable->traceTableLabel = AP.GetTempSymbol("gc_stack", nextLabel++);

                // Add to folding set
                traceTables.InsertNode(sTable, insertPos);

                // Generate the trace table
                outStream.AddBlankLine();
                AP.EmitAlignment(addressAlignLog);

                // First the field offset descriptor
                outStream.EmitLabel(sTable->traceTableLabel);
                size_t traceMethodCount = sTable->traceMethods.size();
                if (!sTable->fieldOffsets.empty()) {
                    outStream.EmitIntValue(traceMethodCount == 0 ? 1 : 0, 2, 0);
                    outStream.EmitIntValue(sTable->fieldOffsets.size(), 2, 0);
                    outStream.EmitIntValue(0, 4, 0);
                    outStream.EmitSymbolValue(sTable->fieldOffsetsLabel, pointerSize, 0);
                }

                // Next the trace method descriptors
                for (size_t i = 0; i < traceMethodCount; ++i) {
                    const TraceMethodEntry * tm = &sTable->traceMethods[i];
                    const Function * method = dyn_cast<Function>(tm->method());
                    if (method == NULL) {
                        method = cast<Function>(tm->method()->getOperand(0));
                    }

                    outStream.EmitIntValue((i + 1 == traceMethodCount ? 1 : 0), 2, 0);
                    outStream.EmitIntValue(0, 2, 0);
                    outStream.EmitIntValue(tm->offset(), 4, 0);
                    MCSymbol * methodSym = AP.Mang->getSymbol(method);
                    outStream.EmitSymbolValue(methodSym, pointerSize, 0);

                }

                // Now emit the field offset array
                outStream.AddBlankLine();
                AP.EmitAlignment(addressAlignLog);

                outStream.EmitLabel(sTable->fieldOffsetsLabel);