[CodeView] Use assembler directives for line tables

Adds a new family of .cv_* directives to LLVM's variant of GAS syntax:

- .cv_file: Similar to DWARF .file directives

- .cv_loc: Similar to the DWARF .loc directive, but starts with a
  function id. CodeView line tables are emitted by function instead of
  by compilation unit, so we needed an extra field to communicate this.
  Rather than overloading the .loc direction further, we decided it was
  better to have our own directive.

- .cv_stringtable: Emits the codeview string table at the current
  position. Currently this just contains the filenames as
  null-terminated strings.

- .cv_filechecksums: Emits the file checksum table for all files used
  with .cv_file so far. There is currently no support for emitting
  actual checksums, just filenames.

This moves the line table emission code down into the assembler.  This
is in preparation for implementing the inlined call site line table
format. The inline line table format encoding algorithm requires knowing
the absolute code offsets, so it must run after the assembler has laid
out the code.

David Majnemer collaborated on this patch.

llvm-svn: 259117

1 files changed, 31 insertions, 0 deletions

diff --git a/llvm/lib/MC/MCObjectStreamer.cpp b/llvm/lib/MC/MCObjectStreamer.cpp
index 39755e5b0a8..71d578aca9d 100644
--- a/llvm/lib/MC/MCObjectStreamer.cpp
+++ b/llvm/lib/MC/MCObjectStreamer.cpp
@@ -125,6 +125,7 @@ void MCObjectStreamer::EmitValueImpl(const MCExpr *Value, unsigned Size,
   MCDataFragment *DF = getOrCreateDataFragment();
   flushPendingLabels(DF, DF->getContents().size());
 
+  MCCVLineEntry::Make(this);
   MCDwarfLineEntry::Make(this, getCurrentSection().first);
 
   // Avoid fixups when possible.
@@ -232,6 +233,7 @@ void MCObjectStreamer::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.
+  MCCVLineEntry::Make(this);
   MCDwarfLineEntry::Make(this, getCurrentSection().first);
 
   // If this instruction doesn't need relaxation, just emit it as data.
@@ -362,7 +364,36 @@ void MCObjectStreamer::EmitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel,
   insert(new MCDwarfCallFrameFragment(*AddrDelta));
 }
 
+void MCObjectStreamer::EmitCVLocDirective(unsigned FunctionId, unsigned FileNo,
+                                          unsigned Line, unsigned Column,
+                                          bool PrologueEnd, bool IsStmt,
+                                          StringRef FileName) {
+  // In case we see two .cv_loc directives in a row, make sure the
+  // first one gets a line entry.
+  MCCVLineEntry::Make(this);
+
+  this->MCStreamer::EmitCVLocDirective(FunctionId, FileNo, Line, Column,
+                                       PrologueEnd, IsStmt, FileName);
+}
+
+void MCObjectStreamer::EmitCVLinetableDirective(unsigned FunctionId,
+                                                const MCSymbol *Begin,
+                                                const MCSymbol *End) {
+  getContext().getCVContext().emitLineTableForFunction(*this, FunctionId, Begin,
+                                                       End);
+  this->MCStreamer::EmitCVLinetableDirective(FunctionId, Begin, End);
+}
+
+void MCObjectStreamer::EmitCVStringTableDirective() {
+  getContext().getCVContext().emitStringTable(*this);
+}
+void MCObjectStreamer::EmitCVFileChecksumsDirective() {
+  getContext().getCVContext().emitFileChecksums(*this);
+}
+
+
 void MCObjectStreamer::EmitBytes(StringRef Data) {
+  MCCVLineEntry::Make(this);
   MCDwarfLineEntry::Make(this, getCurrentSection().first);
   MCDataFragment *DF = getOrCreateDataFragment();
   flushPendingLabels(DF, DF->getContents().size());