pdbdump: Do not treat stream 0 pages as allocated pages.

I examined a few PDBs and all of them treated pages for stream 0
are unused, thus they were unmarked in their free page bitmap.
I think we should do the same thing for compatibility.

Differential Revision: https://reviews.llvm.org/D23047

llvm-svn: 277545

1 files changed, 8 insertions, 6 deletions

diff --git a/llvm/tools/llvm-pdbdump/LLVMOutputStyle.cpp b/llvm/tools/llvm-pdbdump/LLVMOutputStyle.cpp
index 6c39044dbbd..3018a70d4c0 100644
--- a/llvm/tools/llvm-pdbdump/LLVMOutputStyle.cpp
+++ b/llvm/tools/llvm-pdbdump/LLVMOutputStyle.cpp
@@ -303,14 +303,16 @@ Error LLVMOutputStyle::dumpFreePageMap() {
 
   recordKnownUsedPage(PS, File.getBlockMapIndex()); // Stream Table
 
-  for (auto DB : File.getDirectoryBlockArray()) {
+  for (auto DB : File.getDirectoryBlockArray())
     recordKnownUsedPage(PS, DB);
-  }
-  for (auto &SE : File.getStreamMap()) {
-    for (auto &S : SE) {
+
+  // Record pages used by streams. Note that pages for stream 0
+  // are considered being unused because that's what MSVC tools do.
+  // Stream 0 doesn't contain actual data, so it makes some sense,
+  // though it's a bit confusing to us.
+  for (auto &SE : File.getStreamMap().drop_front(1))
+    for (auto &S : SE)
       recordKnownUsedPage(PS, S);
-    }
-  }
 
   dumpBitVector("Msf Free Pages", FPM);
   dumpBitVector("Orphaned Pages", PS.OrphanedPages);