280 lines
10 KiB
C++
280 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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#define DEBUG_TYPE "asm-printer"
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#include "llvm/CodeGen/AsmPrinter.h"
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#include "llvm/CodeGen/MachineLocation.h"
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#include "llvm/MC/MCAsmInfo.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/Target/TargetData.h"
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#include "llvm/Target/TargetFrameInfo.h"
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#include "llvm/Target/TargetLoweringObjectFile.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Target/TargetRegisterInfo.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/Support/Dwarf.h"
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using namespace llvm;
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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(int Value, const char *Desc) const {
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if (isVerbose() && Desc)
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OutStreamer.AddComment(Desc);
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if (MAI->hasLEB128() && OutStreamer.hasRawTextSupport()) {
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// FIXME: MCize.
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OutStreamer.EmitRawText("\t.sleb128\t" + Twine(Value));
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return;
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}
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// If we don't have .sleb128, emit as .bytes.
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int Sign = Value >> (8 * sizeof(Value) - 1);
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bool IsMore;
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do {
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unsigned char Byte = static_cast<unsigned char>(Value & 0x7f);
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Value >>= 7;
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IsMore = Value != Sign || ((Byte ^ Sign) & 0x40) != 0;
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if (IsMore) Byte |= 0x80;
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OutStreamer.EmitIntValue(Byte, 1, /*addrspace*/0);
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} while (IsMore);
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}
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/// EmitULEB128 - emit the specified signed leb128 value.
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void AsmPrinter::EmitULEB128(unsigned 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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if (MAI->hasLEB128() && PadTo == 0 && OutStreamer.hasRawTextSupport()) {
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// FIXME: MCize.
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OutStreamer.EmitRawText("\t.uleb128\t" + Twine(Value));
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return;
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}
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// If we don't have .uleb128 or we want to emit padding, emit as .bytes.
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do {
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unsigned char Byte = static_cast<unsigned char>(Value & 0x7f);
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Value >>= 7;
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if (Value || PadTo != 0) Byte |= 0x80;
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OutStreamer.EmitIntValue(Byte, 1, /*addrspace*/0);
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} while (Value);
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if (PadTo) {
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if (PadTo > 1)
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OutStreamer.EmitFill(PadTo - 1, 0x80/*fillval*/, 0/*addrspace*/);
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OutStreamer.EmitFill(1, 0/*fillval*/, 0/*addrspace*/);
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}
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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, 0/*addrspace*/);
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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: return "absptr";
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case dwarf::DW_EH_PE_omit: return "omit";
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case dwarf::DW_EH_PE_pcrel: return "pcrel";
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case dwarf::DW_EH_PE_udata4: return "udata4";
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case dwarf::DW_EH_PE_udata8: return "udata8";
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case dwarf::DW_EH_PE_sdata4: return "sdata4";
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case dwarf::DW_EH_PE_sdata8: return "sdata8";
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case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4: return "pcrel udata4";
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case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4: return "pcrel sdata4";
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case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8: return "pcrel udata8";
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case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8: 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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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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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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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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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 != 0)
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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 = ") +
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DecodeDWARFEncoding(Val));
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}
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OutStreamer.EmitIntValue(Val, 1, 0/*addrspace*/);
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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: assert(0 && "Invalid encoded value.");
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case dwarf::DW_EH_PE_absptr: return TM.getTargetData()->getPointerSize();
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case dwarf::DW_EH_PE_udata2: return 2;
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case dwarf::DW_EH_PE_udata4: return 4;
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case dwarf::DW_EH_PE_udata8: return 8;
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}
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}
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void AsmPrinter::EmitReference(const MCSymbol *Sym, unsigned Encoding) const {
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const TargetLoweringObjectFile &TLOF = getObjFileLowering();
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const MCExpr *Exp =
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TLOF.getExprForDwarfReference(Sym, Mang, MMI, Encoding, OutStreamer);
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OutStreamer.EmitValue(Exp, GetSizeOfEncodedValue(Encoding), /*addrspace*/0);
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}
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void AsmPrinter::EmitReference(const GlobalValue *GV, unsigned Encoding)const{
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const TargetLoweringObjectFile &TLOF = getObjFileLowering();
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const MCExpr *Exp =
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TLOF.getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, OutStreamer);
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OutStreamer.EmitValue(Exp, GetSizeOfEncodedValue(Encoding), /*addrspace*/0);
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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 (const char *SecOffDir = MAI->getDwarfSectionOffsetDirective()) {
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// FIXME: MCize.
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OutStreamer.EmitRawText(SecOffDir + Twine(Label->getName()));
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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, 0/*AddrSpace*/);
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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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//===----------------------------------------------------------------------===//
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// Dwarf Lowering Routines
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//===----------------------------------------------------------------------===//
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/// EmitFrameMoves - Emit frame instructions to describe the layout of the
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/// frame.
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void AsmPrinter::EmitFrameMoves(const std::vector<MachineMove> &Moves,
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MCSymbol *BaseLabel, bool isEH) const {
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const TargetRegisterInfo *RI = TM.getRegisterInfo();
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int stackGrowth = TM.getTargetData()->getPointerSize();
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if (TM.getFrameInfo()->getStackGrowthDirection() !=
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TargetFrameInfo::StackGrowsUp)
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stackGrowth *= -1;
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for (unsigned i = 0, N = Moves.size(); i < N; ++i) {
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const MachineMove &Move = Moves[i];
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MCSymbol *Label = Move.getLabel();
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// Throw out move if the label is invalid.
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if (Label && !Label->isDefined()) continue; // Not emitted, in dead code.
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const MachineLocation &Dst = Move.getDestination();
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const MachineLocation &Src = Move.getSource();
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// Advance row if new location.
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if (BaseLabel && Label) {
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MCSymbol *ThisSym = Label;
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if (ThisSym != BaseLabel) {
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EmitCFAByte(dwarf::DW_CFA_advance_loc4);
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EmitLabelDifference(ThisSym, BaseLabel, 4);
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BaseLabel = ThisSym;
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}
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}
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// If advancing cfa.
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if (Dst.isReg() && Dst.getReg() == MachineLocation::VirtualFP) {
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assert(!Src.isReg() && "Machine move not supported yet.");
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if (Src.getReg() == MachineLocation::VirtualFP) {
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EmitCFAByte(dwarf::DW_CFA_def_cfa_offset);
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} else {
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EmitCFAByte(dwarf::DW_CFA_def_cfa);
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EmitULEB128(RI->getDwarfRegNum(Src.getReg(), isEH), "Register");
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}
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EmitULEB128(-Src.getOffset(), "Offset");
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continue;
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}
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if (Src.isReg() && Src.getReg() == MachineLocation::VirtualFP) {
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assert(Dst.isReg() && "Machine move not supported yet.");
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EmitCFAByte(dwarf::DW_CFA_def_cfa_register);
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EmitULEB128(RI->getDwarfRegNum(Dst.getReg(), isEH), "Register");
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continue;
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}
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unsigned Reg = RI->getDwarfRegNum(Src.getReg(), isEH);
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int Offset = Dst.getOffset() / stackGrowth;
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if (Offset < 0) {
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EmitCFAByte(dwarf::DW_CFA_offset_extended_sf);
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EmitULEB128(Reg, "Reg");
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EmitSLEB128(Offset, "Offset");
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} else if (Reg < 64) {
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EmitCFAByte(dwarf::DW_CFA_offset + Reg);
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EmitULEB128(Offset, "Offset");
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} else {
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EmitCFAByte(dwarf::DW_CFA_offset_extended);
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EmitULEB128(Reg, "Reg");
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EmitULEB128(Offset, "Offset");
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}
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}
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}
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