COFF: add support for .file symbols

Add support for emitting .file records.  This is mostly a quality of
implementation change (more complete support for COFF file emission) that was
noticed while working on COFF file emission for Windows on ARM.

A .file record is emitted as a symbol with storage class FILE (103) and the name
".file".  A series of auxiliary format 4 records follow which contain the file
name.  The filename is stored as an ANSI string and is padded with NULL if the
length is not a multiple of COFF::SymbolSize (18).

llvm-svn: 206355

2 files changed, 30 insertions, 2 deletions

diff --git a/llvm/lib/MC/WinCOFFObjectWriter.cpp b/llvm/lib/MC/WinCOFFObjectWriter.cpp
index 208dc476bdd..e98777894a7 100644
--- a/llvm/lib/MC/WinCOFFObjectWriter.cpp
+++ b/llvm/lib/MC/WinCOFFObjectWriter.cpp
@@ -633,6 +633,35 @@ void WinCOFFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
   // "Define" each section & symbol. This creates section & symbol
   // entries in the staging area.
 
+  static_assert(sizeof(COFF::AuxiliaryFile::FileName) == COFF::SymbolSize,
+                "size mismatch for COFF::AuxiliaryFile::FileName");
+  for (auto FI = Asm.file_names_begin(), FE = Asm.file_names_end();
+       FI != FE; ++FI) {
+    // round up to calculate the number of auxiliary symbols required
+    unsigned Count = (FI->size() + COFF::SymbolSize) / COFF::SymbolSize;
+
+    COFFSymbol *file = createSymbol(".file");
+    file->Data.StorageClass = COFF::IMAGE_SYM_CLASS_FILE;
+    file->Aux.resize(Count);
+
+    unsigned Offset = 0;
+    unsigned Length = FI->size();
+    for (auto & Aux : file->Aux) {
+      Aux.AuxType = ATFile;
+
+      if (Length > COFF::SymbolSize) {
+        memcpy(Aux.Aux.File.FileName, FI->c_str() + Offset, COFF::SymbolSize);
+        Length = Length - COFF::SymbolSize;
+      } else {
+        memcpy(Aux.Aux.File.FileName, FI->c_str() + Offset, Length);
+        memset(&Aux.Aux.File.FileName[Length], 0, COFF::SymbolSize - Length);
+        Length = 0;
+      }
+
+      Offset = Offset + COFF::SymbolSize;
+    }
+  }
+
   for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e; i++)
     DefineSection(*i);
 
diff --git a/llvm/lib/MC/WinCOFFStreamer.cpp b/llvm/lib/MC/WinCOFFStreamer.cpp
index f422a7437ea..9f033d415dd 100644
--- a/llvm/lib/MC/WinCOFFStreamer.cpp
+++ b/llvm/lib/MC/WinCOFFStreamer.cpp
@@ -266,8 +266,7 @@ void WinCOFFStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
 }
 
 void WinCOFFStreamer::EmitFileDirective(StringRef Filename) {
-  // Ignore for now, linkers don't care, and proper debug
-  // info will be a much large effort.
+  getAssembler().addFileName(Filename);
 }
 
 // TODO: Implement this if you want to emit .comment section in COFF obj files.