forked from OSchip/llvm-project
288 lines
10 KiB
C++
288 lines
10 KiB
C++
//===-- AsmPrinterDwarf.cpp - AsmPrinter Dwarf Support --------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the Dwarf emissions parts of AsmPrinter.
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//
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//===----------------------------------------------------------------------===//
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#include "ByteStreamer.h"
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#include "DwarfExpression.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/CodeGen/AsmPrinter.h"
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#include "llvm/CodeGen/MachineModuleInfo.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/MC/MCAsmInfo.h"
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#include "llvm/MC/MCRegisterInfo.h"
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#include "llvm/MC/MCSection.h"
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#include "llvm/MC/MCStreamer.h"
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#include "llvm/MC/MCSymbol.h"
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#include "llvm/MC/MachineLocation.h"
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#include "llvm/Support/Dwarf.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Target/TargetLoweringObjectFile.h"
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#include "llvm/Target/TargetMachine.h"
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using namespace llvm;
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#define DEBUG_TYPE "asm-printer"
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void DebugLocDwarfExpression::EmitOp(uint8_t Op, const char *Comment) {
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BS.EmitInt8(
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Op, Comment ? Twine(Comment) + " " + dwarf::OperationEncodingString(Op)
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: dwarf::OperationEncodingString(Op));
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}
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void DebugLocDwarfExpression::EmitSigned(int Value) {
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BS.EmitSLEB128(Value, Twine(Value));
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}
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void DebugLocDwarfExpression::EmitUnsigned(unsigned Value) {
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BS.EmitULEB128(Value, Twine(Value));
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}
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bool DebugLocDwarfExpression::isFrameRegister(unsigned MachineReg) {
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// This information is not available while emitting .debug_loc entries.
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return false;
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}
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//===----------------------------------------------------------------------===//
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// Dwarf Emission Helper Routines
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//===----------------------------------------------------------------------===//
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/// EmitSLEB128 - emit the specified signed leb128 value.
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void AsmPrinter::EmitSLEB128(int64_t Value, const char *Desc) const {
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if (isVerbose() && Desc)
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OutStreamer.AddComment(Desc);
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OutStreamer.EmitSLEB128IntValue(Value);
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}
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/// EmitULEB128 - emit the specified signed leb128 value.
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void AsmPrinter::EmitULEB128(uint64_t Value, const char *Desc,
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unsigned PadTo) const {
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if (isVerbose() && Desc)
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OutStreamer.AddComment(Desc);
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OutStreamer.EmitULEB128IntValue(Value, PadTo);
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}
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/// EmitCFAByte - Emit a .byte 42 directive for a DW_CFA_xxx value.
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void AsmPrinter::EmitCFAByte(unsigned Val) const {
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if (isVerbose()) {
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if (Val >= dwarf::DW_CFA_offset && Val < dwarf::DW_CFA_offset + 64)
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OutStreamer.AddComment("DW_CFA_offset + Reg (" +
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Twine(Val - dwarf::DW_CFA_offset) + ")");
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else
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OutStreamer.AddComment(dwarf::CallFrameString(Val));
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}
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OutStreamer.EmitIntValue(Val, 1);
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}
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static const char *DecodeDWARFEncoding(unsigned Encoding) {
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switch (Encoding) {
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case dwarf::DW_EH_PE_absptr:
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return "absptr";
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case dwarf::DW_EH_PE_omit:
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return "omit";
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case dwarf::DW_EH_PE_pcrel:
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return "pcrel";
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case dwarf::DW_EH_PE_udata4:
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return "udata4";
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case dwarf::DW_EH_PE_udata8:
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return "udata8";
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case dwarf::DW_EH_PE_sdata4:
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return "sdata4";
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case dwarf::DW_EH_PE_sdata8:
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return "sdata8";
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case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4:
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return "pcrel udata4";
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case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4:
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return "pcrel sdata4";
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case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8:
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return "pcrel udata8";
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case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8:
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return "pcrel sdata8";
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case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4
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:
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return "indirect pcrel udata4";
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case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
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:
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return "indirect pcrel sdata4";
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case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8
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:
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return "indirect pcrel udata8";
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case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8
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:
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return "indirect pcrel sdata8";
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}
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return "<unknown encoding>";
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}
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/// EmitEncodingByte - Emit a .byte 42 directive that corresponds to an
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/// encoding. If verbose assembly output is enabled, we output comments
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/// describing the encoding. Desc is an optional string saying what the
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/// encoding is specifying (e.g. "LSDA").
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void AsmPrinter::EmitEncodingByte(unsigned Val, const char *Desc) const {
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if (isVerbose()) {
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if (Desc)
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OutStreamer.AddComment(Twine(Desc) + " Encoding = " +
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Twine(DecodeDWARFEncoding(Val)));
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else
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OutStreamer.AddComment(Twine("Encoding = ") + DecodeDWARFEncoding(Val));
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}
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OutStreamer.EmitIntValue(Val, 1);
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}
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/// GetSizeOfEncodedValue - Return the size of the encoding in bytes.
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unsigned AsmPrinter::GetSizeOfEncodedValue(unsigned Encoding) const {
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if (Encoding == dwarf::DW_EH_PE_omit)
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return 0;
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switch (Encoding & 0x07) {
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default:
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llvm_unreachable("Invalid encoded value.");
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case dwarf::DW_EH_PE_absptr:
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return TM.getDataLayout()->getPointerSize();
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case dwarf::DW_EH_PE_udata2:
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return 2;
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case dwarf::DW_EH_PE_udata4:
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return 4;
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case dwarf::DW_EH_PE_udata8:
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return 8;
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}
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}
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void AsmPrinter::EmitTTypeReference(const GlobalValue *GV,
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unsigned Encoding) const {
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if (GV) {
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const TargetLoweringObjectFile &TLOF = getObjFileLowering();
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const MCExpr *Exp =
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TLOF.getTTypeGlobalReference(GV, Encoding, *Mang, TM, MMI, OutStreamer);
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OutStreamer.EmitValue(Exp, GetSizeOfEncodedValue(Encoding));
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} else
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OutStreamer.EmitIntValue(0, GetSizeOfEncodedValue(Encoding));
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}
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/// EmitSectionOffset - Emit the 4-byte offset of Label from the start of its
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/// section. This can be done with a special directive if the target supports
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/// it (e.g. cygwin) or by emitting it as an offset from a label at the start
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/// of the section.
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///
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/// SectionLabel is a temporary label emitted at the start of the section that
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/// Label lives in.
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void AsmPrinter::EmitSectionOffset(const MCSymbol *Label,
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const MCSymbol *SectionLabel) const {
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// On COFF targets, we have to emit the special .secrel32 directive.
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if (MAI->needsDwarfSectionOffsetDirective()) {
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OutStreamer.EmitCOFFSecRel32(Label);
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return;
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}
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// Get the section that we're referring to, based on SectionLabel.
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const MCSection &Section = SectionLabel->getSection();
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// If Label has already been emitted, verify that it is in the same section as
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// section label for sanity.
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assert((!Label->isInSection() || &Label->getSection() == &Section) &&
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"Section offset using wrong section base for label");
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// If the section in question will end up with an address of 0 anyway, we can
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// just emit an absolute reference to save a relocation.
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if (Section.isBaseAddressKnownZero()) {
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OutStreamer.EmitSymbolValue(Label, 4);
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return;
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}
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// Otherwise, emit it as a label difference from the start of the section.
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EmitLabelDifference(Label, SectionLabel, 4);
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}
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// Some targets do not provide a DWARF register number for every
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// register. This function attempts to emit a DWARF register by
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// emitting a piece of a super-register or by piecing together
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// multiple subregisters that alias the register.
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void AsmPrinter::EmitDwarfRegOpPiece(ByteStreamer &Streamer,
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const MachineLocation &MLoc,
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unsigned PieceSizeInBits,
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unsigned PieceOffsetInBits) const {
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assert(MLoc.isReg() && "MLoc must be a register");
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DebugLocDwarfExpression Expr(*this, Streamer);
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Expr.AddMachineRegPiece(MLoc.getReg(), PieceSizeInBits, PieceOffsetInBits);
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}
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void AsmPrinter::EmitDwarfOpPiece(ByteStreamer &Streamer,
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unsigned PieceSizeInBits,
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unsigned PieceOffsetInBits) const {
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DebugLocDwarfExpression Expr(*this, Streamer);
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Expr.AddOpPiece(PieceSizeInBits, PieceOffsetInBits);
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}
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/// EmitDwarfRegOp - Emit dwarf register operation.
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void AsmPrinter::EmitDwarfRegOp(ByteStreamer &Streamer,
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const MachineLocation &MLoc) const {
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DebugLocDwarfExpression Expr(*this, Streamer);
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const MCRegisterInfo *MRI = MMI->getContext().getRegisterInfo();
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int Reg = MRI->getDwarfRegNum(MLoc.getReg(), false);
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if (Reg < 0) {
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// We assume that pointers are always in an addressable register.
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if (MLoc.isIndirect())
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// FIXME: We have no reasonable way of handling errors in here. The
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// caller might be in the middle of a dwarf expression. We should
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// probably assert that Reg >= 0 once debug info generation is more
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// mature.
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return Expr.EmitOp(dwarf::DW_OP_nop,
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"nop (could not find a dwarf register number)");
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// Attempt to find a valid super- or sub-register.
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if (!Expr.AddMachineRegPiece(MLoc.getReg()))
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Expr.EmitOp(dwarf::DW_OP_nop,
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"nop (could not find a dwarf register number)");
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return;
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}
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if (MLoc.isIndirect())
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Expr.AddRegIndirect(Reg, MLoc.getOffset());
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else
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Expr.AddReg(Reg);
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}
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//===----------------------------------------------------------------------===//
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// Dwarf Lowering Routines
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//===----------------------------------------------------------------------===//
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void AsmPrinter::emitCFIInstruction(const MCCFIInstruction &Inst) const {
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switch (Inst.getOperation()) {
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default:
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llvm_unreachable("Unexpected instruction");
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case MCCFIInstruction::OpDefCfaOffset:
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OutStreamer.EmitCFIDefCfaOffset(Inst.getOffset());
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break;
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case MCCFIInstruction::OpDefCfa:
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OutStreamer.EmitCFIDefCfa(Inst.getRegister(), Inst.getOffset());
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break;
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case MCCFIInstruction::OpDefCfaRegister:
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OutStreamer.EmitCFIDefCfaRegister(Inst.getRegister());
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break;
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case MCCFIInstruction::OpOffset:
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OutStreamer.EmitCFIOffset(Inst.getRegister(), Inst.getOffset());
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break;
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case MCCFIInstruction::OpRegister:
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OutStreamer.EmitCFIRegister(Inst.getRegister(), Inst.getRegister2());
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break;
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case MCCFIInstruction::OpWindowSave:
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OutStreamer.EmitCFIWindowSave();
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break;
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case MCCFIInstruction::OpSameValue:
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OutStreamer.EmitCFISameValue(Inst.getRegister());
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break;
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}
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}
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