This is the last major patch to implement support for the .loc directive

and output the dwarf line number tables.  This contains the code to emit and
encode the dwarf line tables from the previously gathered information in the
MCLineSection objects.  This contains all the details to encode the line and
address deltas into the dwarf line table.

To do this an MCDwarfLineAddrFragment has been added.

Also this moves the interface code out of Mach-O streamer into
MCDwarf so it should be useable by other object file formats.

There is now one call to be made from an MCObjectStreamer
EmitInstruction() method:
   MCLineEntry::Make(this, getCurrentSection());
to create a line entry after each instruction is assembled.

And one call call to be made from an MCObjectStreamer Finish() method:
   MCDwarfFileTable::Emit(this, DwarfLineSection);
when getContext().hasDwarfFiles() is true and is passed a object file specific
MCSection where to emit the dwarf file and the line tables.

This appears to now be correct for 32-bit targets, at least x86.  But the
relocation entries for 64-bit Darwin needs some further work which is next
up to work on.  So for now the 64-bit Mach-O target does not output the
dwarf file and line tables.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115157 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 17 insertions, 204 deletions

diff --git a/lib/MC/MCMachOStreamer.cpp b/lib/MC/MCMachOStreamer.cpp
index a0695058e2..42de0ae1b5 100644
--- a/lib/MC/MCMachOStreamer.cpp
+++ b/lib/MC/MCMachOStreamer.cpp
@@ -20,6 +20,7 @@
 #include "llvm/MC/MCMachOSymbolFlags.h"
 #include "llvm/MC/MCSectionMachO.h"
 #include "llvm/MC/MCDwarf.h"
+#include "llvm/Support/Dwarf.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetAsmBackend.h"
@@ -32,11 +33,6 @@ class MCMachOStreamer : public MCObjectStreamer {
 private:
   void EmitInstToFragment(const MCInst &Inst);
   void EmitInstToData(const MCInst &Inst);
-  // FIXME: These will likely moved to a better place.
-  void MakeLineEntryForSection(const MCSection *Section);
-  const MCExpr * MakeStartMinusEndExpr(MCSymbol *Start, MCSymbol *End,
-                                                        int IntVal);
-  void EmitDwarfFileTable(void);
 
 public:
   MCMachOStreamer(MCContext &Context, TargetAsmBackend &TAB,
@@ -420,7 +416,7 @@ void MCMachOStreamer::EmitInstruction(const MCInst &Inst) {
 
   // Now that a machine instruction has been assembled into this section, make
   // a line entry for any .loc directive that has been seen.
-  MakeLineEntryForSection(getCurrentSection());
+  MCLineEntry::Make(this, getCurrentSection());
 
   // If this instruction doesn't need relaxation, just emit it as data.
   if (!getAssembler().getBackend().MayNeedRelaxation(Inst)) {
@@ -443,206 +439,23 @@ void MCMachOStreamer::EmitInstruction(const MCInst &Inst) {
   EmitInstToFragment(Inst);
 }
 
-//
-// This is called when an instruction is assembled into the specified section
-// and if there is information from the last .loc directive that has yet to have
-// a line entry made for it is made.
-//
-void MCMachOStreamer::MakeLineEntryForSection(const MCSection *Section) {
-  if (!getContext().getDwarfLocSeen())
-    return;
-
-  // Create a symbol at in the current section for use in the line entry.
-  MCSymbol *LineSym = getContext().CreateTempSymbol();
-  // Set the value of the symbol to use for the MCLineEntry.
-  EmitLabel(LineSym);
-
-  // Get the current .loc info saved in the context.
-  const MCDwarfLoc &DwarfLoc = getContext().getCurrentDwarfLoc();
-
-  // Create a (local) line entry with the symbol and the current .loc info.
-  MCLineEntry LineEntry(LineSym, DwarfLoc);
-
-  // clear DwarfLocSeen saying the current .loc info is now used.
-  getContext().clearDwarfLocSeen();
-
-  // Get the MCLineSection for this section, if one does not exist for this
-  // section create it.
-  DenseMap<const MCSection *, MCLineSection *> &MCLineSections =
-    getContext().getMCLineSections();
-  MCLineSection *LineSection = MCLineSections[Section];
-  if (!LineSection) {
-    // Create a new MCLineSection.  This will be deleted after the dwarf line
-    // table is created using it by iterating through the MCLineSections
-    // DenseMap.
-    LineSection = new MCLineSection;
-    // Save a pointer to the new LineSection into the MCLineSections DenseMap.
-    MCLineSections[Section] = LineSection;
-  }
-
-  // Add the line entry to this section's entries.
-  LineSection->addLineEntry(LineEntry);
-}
-
-//
-// This helper routine returns an expression of End - Start + IntVal for use
-// by EmitDwarfFileTable() below.
-// 
-const MCExpr * MCMachOStreamer::MakeStartMinusEndExpr(MCSymbol *Start,
-                                                      MCSymbol *End,
-                                                      int IntVal) {
-  MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
-  const MCExpr *Res =
-    MCSymbolRefExpr::Create(End, Variant, getContext());
-  const MCExpr *RHS =
-    MCSymbolRefExpr::Create(Start, Variant, getContext());
-  const MCExpr *Res1 =
-    MCBinaryExpr::Create(MCBinaryExpr::Sub, Res, RHS,getContext());
-  const MCExpr *Res2 =
-    MCConstantExpr::Create(IntVal, getContext());
-  const MCExpr *Res3 =
-    MCBinaryExpr::Create(MCBinaryExpr::Sub, Res1, Res2, getContext());
-  return Res3;
-}
-
-//
-// This emits the Dwarf file (and eventually the line) table.
-//
-void MCMachOStreamer::EmitDwarfFileTable(void) {
-  // For now make sure we don't put out the Dwarf file table if no .file
-  // directives were seen.
-  const std::vector<MCDwarfFile *> &MCDwarfFiles =
-    getContext().getMCDwarfFiles();
-  if (MCDwarfFiles.size() == 0)
-    return;
-
-  // This is the Mach-O section, for ELF it is the .debug_line section.
-  SwitchSection(getContext().getMachOSection("__DWARF", "__debug_line",
+void MCMachOStreamer::Finish() {
+  // Dump out the dwarf file & directory tables and line tables.
+  if (getContext().hasDwarfFiles() &&
+      // TODO: This not enabled for 64-bit Mach-O targets.  As there are needed
+      // changes in the handling of 64-bit relocation entries for dwarf Mach-O
+      // sections that need to made.  Currently it gets
+      //   LLVM ERROR: unsupported local relocations in difference
+      // due dealing with "a-b" expressions made up for dwarf line entries
+      // because the line section has no non-local symbols thus it can't find
+      // an atom symbol for the base.
+      getAssembler().getBackend().getPointerSize() != 8) {
+    const MCSection *DwarfLineSection = getContext().getMachOSection("__DWARF",
+                                         "__debug_line",
                                          MCSectionMachO::S_ATTR_DEBUG,
-                                         0, SectionKind::getDataRelLocal()));
-
-  // Create a symbol at the beginning of this section.
-  MCSymbol *LineStartSym = getContext().CreateTempSymbol();
-  // Set the value of the symbol, as we are at the start of the section.
-  EmitLabel(LineStartSym);
-
-  // Create a symbol for the end of the section (to be set when we get there).
-  MCSymbol *LineEndSym = getContext().CreateTempSymbol();
-
-  // The first 4 bytes is the total length of the information for this
-  // compilation unit (not including these 4 bytes for the length).
-  EmitValue(MakeStartMinusEndExpr(LineStartSym, LineEndSym, 4), 4, 0);
-
-  // Next 2 bytes is the Version, which is Dwarf 2.
-  EmitIntValue(2, 2);
-
-  // Create a symbol for the end of the prologue (to be set when we get there).
-  MCSymbol *ProEndSym = getContext().CreateTempSymbol(); // Lprologue_end
-
-  // Length of the prologue, is the next 4 bytes.  Which is the start of the
-  // section to the end of the prologue.  Not including the 4 bytes for the
-  // total length, the 2 bytes for the version, and these 4 bytes for the
-  // length of the prologue.
-  EmitValue(MakeStartMinusEndExpr(LineStartSym, ProEndSym, (4 + 2 + 4)), 4, 0);
-
-  // Parameters of the state machine, are next.
-  //  Define the architecture-dependent minimum instruction length (in
-  //  bytes).  This value should be rather too small than too big.  */
-  //  DWARF2_LINE_MIN_INSN_LENGTH
-  EmitIntValue(1, 1);
-  //  Flag that indicates the initial value of the is_stmt_start flag.
-  //  DWARF2_LINE_DEFAULT_IS_STMT
-  EmitIntValue(1, 1);
-  //  Minimum line offset in a special line info. opcode.  This value
-  //  was chosen to give a reasonable range of values.  */
-  //  DWARF2_LINE_BASE
-  EmitIntValue(uint64_t(-5), 1);
-  //  Range of line offsets in a special line info. opcode.
-  //  DWARF2_LINE_RANGE
-  EmitIntValue(14, 1);
-  //  First special line opcode - leave room for the standard opcodes.
-  //  DWARF2_LINE_OPCODE_BASE
-  EmitIntValue(13, 1);
-
-  // Standard opcode lengths
-  EmitIntValue(0, 1); // length of DW_LNS_copy
-  EmitIntValue(1, 1); // length of DW_LNS_advance_pc
-  EmitIntValue(1, 1); // length of DW_LNS_advance_line
-  EmitIntValue(1, 1); // length of DW_LNS_set_file
-  EmitIntValue(1, 1); // length of DW_LNS_set_column
-  EmitIntValue(0, 1); // length of DW_LNS_negate_stmt
-  EmitIntValue(0, 1); // length of DW_LNS_set_basic_block
-  EmitIntValue(0, 1); // length of DW_LNS_const_add_pc
-  EmitIntValue(1, 1); // length of DW_LNS_fixed_advance_pc
-  EmitIntValue(0, 1); // length of DW_LNS_set_prologue_end
-  EmitIntValue(0, 1); // length of DW_LNS_set_epilogue_begin
-  EmitIntValue(1, 1); // DW_LNS_set_isa
-
-  // Put out the directory and file tables.
-
-  // First the directory table.
-  const std::vector<StringRef> &MCDwarfDirs =
-    getContext().getMCDwarfDirs();
-  for (unsigned i = 0; i < MCDwarfDirs.size(); i++) {
-    EmitBytes(MCDwarfDirs[i], 0); // the DirectoryName
-    EmitBytes(StringRef("\0", 1), 0); // the null termination of the string
-  }
-  EmitIntValue(0, 1); // Terminate the directory list
-
-  // Second the file table.
-  for (unsigned i = 1; i < MCDwarfFiles.size(); i++) {
-    EmitBytes(MCDwarfFiles[i]->getName(), 0); // FileName
-    EmitBytes(StringRef("\0", 1), 0); // the null termination of the string
-    // FIXME the Directory number should be a .uleb128 not a .byte
-    EmitIntValue(MCDwarfFiles[i]->getDirIndex(), 1);
-    EmitIntValue(0, 1); // last modification timestamp (always 0)
-    EmitIntValue(0, 1); // filesize (always 0)
+                                         0, SectionKind::getDataRelLocal());
+    MCDwarfFileTable::Emit(this, DwarfLineSection);
   }
-  EmitIntValue(0, 1); // Terminate the file list
-
-  // This is the end of the prologue, so set the value of the symbol at the
-  // end of the prologue (that was used in a previous expression).
-  EmitLabel(ProEndSym);
-
-  // TODO: This is the point where the line tables would be emitted.
-
-  // Delete the MCLineSections that were created in 
-  // MCMachOStreamer::MakeLineEntryForSection() and used to emit the line
-  // tables.
-  DenseMap<const MCSection *, MCLineSection *> &MCLineSections =
-    getContext().getMCLineSections();
-  for (DenseMap<const MCSection *, MCLineSection *>::iterator it =
-	MCLineSections.begin(), ie = MCLineSections.end(); it != ie; ++it) {
-    delete it->second;
-  }
-
-  // If there are no line tables emited then we emit:
-  // The following DW_LNE_set_address sequence to set the address to zero
-  //   TODO test for 32-bit or 64-bit output
-  //     This is the sequence for 32-bit code
-  EmitIntValue(0, 1);
-  EmitIntValue(5, 1);
-  EmitIntValue(2, 1);
-  EmitIntValue(0, 1);
-  EmitIntValue(0, 1);
-  EmitIntValue(0, 1);
-  EmitIntValue(0, 1);
-
-  // Lastly emit the DW_LNE_end_sequence which consists of 3 bytes '00 01 01'
-  // (00 is the code for extended opcodes, followed by a ULEB128 length of the
-  // extended opcode (01), and the DW_LNE_end_sequence (01).
-  EmitIntValue(0, 1); // DW_LNS_extended_op
-  EmitIntValue(1, 1); // ULEB128 length of the extended opcode
-  EmitIntValue(1, 1); // DW_LNE_end_sequence
-
-  // This is the end of the section, so set the value of the symbol at the end
-  // of this section (that was used in a previous expression).
-  EmitLabel(LineEndSym);
-}
-
-void MCMachOStreamer::Finish() {
-  // Dump out the dwarf file and directory tables (soon to include line table)
-  EmitDwarfFileTable();
 
   // We have to set the fragment atom associations so we can relax properly for
   // Mach-O.