NFC. Refactored DIPrinter for support embedded source.

This patch introduces source loading and pruning functions.
It will allow to use the DWARF embedded source and use the same code for JSON printout.
No functional changes.

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D102539

Author: orlov-alex

llvm/include/llvm/DebugInfo/Symbolize/DIPrinter.h

@@ -29,6 +29,8 @@ class raw_ostream;
 
 namespace symbolize {
 
+class SourceCode;
+
 struct Request {
   StringRef ModuleName;
   Optional<uint64_t> Address;
@@ -74,7 +76,7 @@ class PlainPrinterBase : public DIPrinter {
   void printFunctionName(StringRef FunctionName, bool Inlined);
   virtual void printSimpleLocation(StringRef Filename,
                                    const DILineInfo &Info) = 0;
-  void printContext(StringRef FileName, int64_t Line);
+  void printContext(SourceCode SourceCode);
   void printVerbose(StringRef Filename, const DILineInfo &Info);
   virtual void printFooter() {}
 

llvm/lib/DebugInfo/Symbolize/DIPrinter.cpp

@@ -30,6 +30,60 @@
 namespace llvm {
 namespace symbolize {
 
+class SourceCode {
+  std::unique_ptr<MemoryBuffer> MemBuf;
+
+  const Optional<StringRef> load(StringRef FileName,
+                                 const Optional<StringRef> &EmbeddedSource) {
+    if (Lines <= 0)
+      return None;
+
+    if (EmbeddedSource)
+      return EmbeddedSource;
+    else {
+      ErrorOr<std::unique_ptr<MemoryBuffer>> BufOrErr =
+          MemoryBuffer::getFile(FileName);
+      if (!BufOrErr)
+        return None;
+      MemBuf = std::move(*BufOrErr);
+      return MemBuf->getBuffer();
+    }
+  }
+
+  const Optional<StringRef> pruneSource(const Optional<StringRef> &Source) {
+    if (!Source)
+      return None;
+    size_t FirstLinePos = StringRef::npos, Pos = 0;
+    for (int64_t L = 1; L <= LastLine; ++L, ++Pos) {
+      if (L == FirstLine)
+        FirstLinePos = Pos;
+      Pos = Source->find('\n', Pos);
+      if (Pos == StringRef::npos)
+        break;
+    }
+    if (FirstLinePos == StringRef::npos)
+      return None;
+    return Source->substr(FirstLinePos, (Pos == StringRef::npos)
+                                            ? StringRef::npos
+                                            : Pos - FirstLinePos);
+  }
+
+public:
+  const int64_t Line;
+  const int Lines;
+  const int64_t FirstLine;
+  const int64_t LastLine;
+  const Optional<StringRef> PrunedSource;
+
+  SourceCode(
+      StringRef FileName, int64_t Line, int Lines,
+      const Optional<StringRef> &EmbeddedSource = Optional<StringRef>(None))
+      : Line(Line), Lines(Lines),
+        FirstLine(std::max(static_cast<int64_t>(1), Line - Lines / 2)),
+        LastLine(FirstLine + Lines - 1),
+        PrunedSource(pruneSource(load(FileName, EmbeddedSource))) {}
+};
+
 void PlainPrinterBase::printHeader(uint64_t Address) {
   if (Config.PrintAddress) {
     OS << "0x";
@@ -40,32 +94,27 @@ void PlainPrinterBase::printHeader(uint64_t Address) {
 }
 
 // Prints source code around in the FileName the Line.
-void PlainPrinterBase::printContext(StringRef FileName, int64_t Line) {
-  if (Config.SourceContextLines <= 0)
+void PlainPrinterBase::printContext(SourceCode SourceCode) {
+  if (!SourceCode.PrunedSource)
     return;
 
-  ErrorOr<std::unique_ptr<MemoryBuffer>> BufOrErr =
-      MemoryBuffer::getFile(FileName);
-  if (!BufOrErr)
-    return;
+  StringRef Source = *SourceCode.PrunedSource;
+  std::string SourceCopy;
+  if (*Source.end() != '\0') {
+    SourceCopy = Source.str();
+    Source = SourceCopy;
+  }
 
-  std::unique_ptr<MemoryBuffer> Buf = std::move(BufOrErr.get());
-  int64_t FirstLine =
-      std::max(static_cast<int64_t>(1), Line - Config.SourceContextLines / 2);
-  int64_t LastLine = FirstLine + Config.SourceContextLines;
-  size_t MaxLineNumberWidth = std::ceil(std::log10(LastLine));
-
-  for (line_iterator I = line_iterator(*Buf, false);
-       !I.is_at_eof() && I.line_number() <= LastLine; ++I) {
-    int64_t L = I.line_number();
-    if (L >= FirstLine && L <= LastLine) {
-      OS << format_decimal(L, MaxLineNumberWidth);
-      if (L == Line)
-        OS << " >: ";
-      else
-        OS << "  : ";
-      OS << *I << "\n";
-    }
+  size_t MaxLineNumberWidth = std::ceil(std::log10(SourceCode.LastLine));
+  for (line_iterator I = line_iterator(MemoryBufferRef(Source, ""), false);
+       !I.is_at_eof(); ++I) {
+    int64_t L = SourceCode.FirstLine + I.line_number() - 1;
+    OS << format_decimal(L, MaxLineNumberWidth);
+    if (L == SourceCode.Line)
+      OS << " >: ";
+    else
+      OS << "  : ";
+    OS << *I << '\n';
   }
 }
 
@@ -82,7 +131,7 @@ void PlainPrinterBase::printFunctionName(StringRef FunctionName, bool Inlined) {
 void LLVMPrinter::printSimpleLocation(StringRef Filename,
                                       const DILineInfo &Info) {
   OS << Filename << ':' << Info.Line << ':' << Info.Column << '\n';
-  printContext(Filename, Info.Line);
+  printContext(SourceCode(Filename, Info.Line, Config.SourceContextLines));
 }
 
 void GNUPrinter::printSimpleLocation(StringRef Filename,
@@ -91,7 +140,7 @@ void GNUPrinter::printSimpleLocation(StringRef Filename,
   if (Info.Discriminator)
     OS << " (discriminator " << Info.Discriminator << ')';
   OS << '\n';
-  printContext(Filename, Info.Line);
+  printContext(SourceCode(Filename, Info.Line, Config.SourceContextLines));
 }
 
 void PlainPrinterBase::printVerbose(StringRef Filename,