Debug Info: store the files and directories for each compile unit.

We now emit a line table for each compile unit. To reduce the prologue size
of each line table, the files and directories used by each compile unit are
stored in std::map<unsigned, std::vector< > > instead of std::vector< >.

The prologue for a lto'ed image can be as big as 93K. Duplicating 93K for each
compile unit causes a huge increase of debug info. With this patch, each
prologue will only emit the files required by the compile unit.

rdar://problem/13342023


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176605 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 7 insertions, 4 deletions

diff --git a/lib/MC/MCContext.cpp b/lib/MC/MCContext.cpp
index 1a7df6041e..26d378e6c0 100644
--- a/lib/MC/MCContext.cpp
+++ b/lib/MC/MCContext.cpp
@@ -77,8 +77,8 @@ void MCContext::reset() {
   Symbols.clear();
   Allocator.Reset();
   Instances.clear();
-  MCDwarfFiles.clear();
-  MCDwarfDirs.clear();
+  MCDwarfFilesCUMap.clear();
+  MCDwarfDirsCUMap.clear();
   MCGenDwarfLabelEntries.clear();
   DwarfDebugFlags = StringRef();
   MCLineSections.clear();
@@ -299,11 +299,13 @@ const MCSection *MCContext::getCOFFSection(StringRef Section,
 /// error and zero is returned and the client reports the error, else the
 /// allocated file number is returned.  The file numbers may be in any order.
 unsigned MCContext::GetDwarfFile(StringRef Directory, StringRef FileName,
-                                 unsigned FileNumber) {
+                                 unsigned FileNumber, unsigned CUID) {
   // TODO: a FileNumber of zero says to use the next available file number.
   // Note: in GenericAsmParser::ParseDirectiveFile() FileNumber was checked
   // to not be less than one.  This needs to be change to be not less than zero.
 
+  std::vector<MCDwarfFile *>& MCDwarfFiles = MCDwarfFilesCUMap[CUID];
+  std::vector<StringRef>& MCDwarfDirs = MCDwarfDirsCUMap[CUID];
   // Make space for this FileNumber in the MCDwarfFiles vector if needed.
   if (FileNumber >= MCDwarfFiles.size()) {
     MCDwarfFiles.resize(FileNumber + 1);
@@ -363,7 +365,8 @@ unsigned MCContext::GetDwarfFile(StringRef Directory, StringRef FileName,
 
 /// isValidDwarfFileNumber - takes a dwarf file number and returns true if it
 /// currently is assigned and false otherwise.
-bool MCContext::isValidDwarfFileNumber(unsigned FileNumber) {
+bool MCContext::isValidDwarfFileNumber(unsigned FileNumber, unsigned CUID) {
+  std::vector<MCDwarfFile *>& MCDwarfFiles = MCDwarfFilesCUMap[CUID];
   if(FileNumber == 0 || FileNumber >= MCDwarfFiles.size())
     return false;