[MC] Add support for encoding CodeView variable definition ranges

CodeView, like most other debug formats, represents the live range of a
variable so that debuggers might print them out.

They use a variety of records to represent how a particular variable
might be available (in a register, in a frame pointer, etc.) along with
a set of ranges where this debug information is relevant.

However, the format only allows us to use ranges which are limited to a
maximum of 0xF000 in size.  This means that we need to split our debug
information into chunks of 0xF000.

Because the layout of code is not known until *very* late, we must use a
new fragment to record the information we need until we can know
*exactly* what the range is.

llvm-svn: 259868

1 files changed, 41 insertions, 2 deletions

diff --git a/llvm/lib/MC/MCParser/AsmParser.cpp b/llvm/lib/MC/MCParser/AsmParser.cpp
index 2db7504b377..1332ef4cde9 100644
--- a/llvm/lib/MC/MCParser/AsmParser.cpp
+++ b/llvm/lib/MC/MCParser/AsmParser.cpp
@@ -358,7 +358,7 @@ private:
     DK_IFNOTDEF, DK_ELSEIF, DK_ELSE, DK_ENDIF,
     DK_SPACE, DK_SKIP, DK_FILE, DK_LINE, DK_LOC, DK_STABS,
     DK_CV_FILE, DK_CV_LOC, DK_CV_LINETABLE, DK_CV_INLINE_LINETABLE,
-    DK_CV_STRINGTABLE, DK_CV_FILECHECKSUMS,
+    DK_CV_DEF_RANGE, DK_CV_STRINGTABLE, DK_CV_FILECHECKSUMS,
     DK_CFI_SECTIONS, DK_CFI_STARTPROC, DK_CFI_ENDPROC, DK_CFI_DEF_CFA,
     DK_CFI_DEF_CFA_OFFSET, DK_CFI_ADJUST_CFA_OFFSET, DK_CFI_DEF_CFA_REGISTER,
     DK_CFI_OFFSET, DK_CFI_REL_OFFSET, DK_CFI_PERSONALITY, DK_CFI_LSDA,
@@ -396,11 +396,13 @@ private:
   bool parseDirectiveLoc();
   bool parseDirectiveStabs();
 
-  // ".cv_file", ".cv_loc", ".cv_linetable", "cv_inline_linetable"
+  // ".cv_file", ".cv_loc", ".cv_linetable", "cv_inline_linetable",
+  // ".cv_def_range"
   bool parseDirectiveCVFile();
   bool parseDirectiveCVLoc();
   bool parseDirectiveCVLinetable();
   bool parseDirectiveCVInlineLinetable();
+  bool parseDirectiveCVDefRange();
   bool parseDirectiveCVStringTable();
   bool parseDirectiveCVFileChecksums();
 
@@ -1656,6 +1658,8 @@ bool AsmParser::parseStatement(ParseStatementInfo &Info,
       return parseDirectiveCVLinetable();
     case DK_CV_INLINE_LINETABLE:
       return parseDirectiveCVInlineLinetable();
+    case DK_CV_DEF_RANGE:
+      return parseDirectiveCVDefRange();
     case DK_CV_STRINGTABLE:
       return parseDirectiveCVStringTable();
     case DK_CV_FILECHECKSUMS:
@@ -3286,6 +3290,40 @@ bool AsmParser::parseDirectiveCVInlineLinetable() {
   return false;
 }
 
+/// parseDirectiveCVDefRange
+/// ::= .cv_def_range RangeStart RangeEnd (GapStart GapEnd)*, bytes*
+bool AsmParser::parseDirectiveCVDefRange() {
+  SMLoc Loc;
+  std::vector<std::pair<const MCSymbol *, const MCSymbol *>> Ranges;
+  while (getLexer().is(AsmToken::Identifier)) {
+    Loc = getLexer().getLoc();
+    StringRef GapStartName;
+    if (parseIdentifier(GapStartName))
+      return Error(Loc, "expected identifier in directive");
+    MCSymbol *GapStartSym = getContext().getOrCreateSymbol(GapStartName);
+
+    Loc = getLexer().getLoc();
+    StringRef GapEndName;
+    if (parseIdentifier(GapEndName))
+      return Error(Loc, "expected identifier in directive");
+    MCSymbol *GapEndSym = getContext().getOrCreateSymbol(GapEndName);
+
+    Ranges.push_back({GapStartSym, GapEndSym});
+  }
+
+  if (getLexer().isNot(AsmToken::Comma))
+    return TokError("unexpected token in directive");
+  Lex();
+
+  std::string FixedSizePortion;
+  if (parseEscapedString(FixedSizePortion))
+    return true;
+  Lex();
+
+  getStreamer().EmitCVDefRangeDirective(Ranges, FixedSizePortion);
+  return false;
+}
+
 /// parseDirectiveCVStringTable
 /// ::= .cv_stringtable
 bool AsmParser::parseDirectiveCVStringTable() {
@@ -4615,6 +4653,7 @@ void AsmParser::initializeDirectiveKindMap() {
   DirectiveKindMap[".cv_loc"] = DK_CV_LOC;
   DirectiveKindMap[".cv_linetable"] = DK_CV_LINETABLE;
   DirectiveKindMap[".cv_inline_linetable"] = DK_CV_INLINE_LINETABLE;
+  DirectiveKindMap[".cv_def_range"] = DK_CV_DEF_RANGE;
   DirectiveKindMap[".cv_stringtable"] = DK_CV_STRINGTABLE;
   DirectiveKindMap[".cv_filechecksums"] = DK_CV_FILECHECKSUMS;
   DirectiveKindMap[".sleb128"] = DK_SLEB128;