[lld] r363724 - [PDB] Ignore .debug$S subsections with high bit set

[Reid Kleckner via llvm-commits]

Author: rnk
Date: Tue Jun 18 12:41:25 2019
New Revision: 363724

URL: http://llvm.org/viewvc/llvm-project?rev=363724&view=rev
Log:
[PDB] Ignore .debug$S subsections with high bit set

Some versions of the Visual C++ 2015 runtime have line tables with the
subsection kind of 0x800000F2. In cvinfo.h, 0x80000000 is documented to
be DEBUG_S_IGNORE. This appears to implement the intended behavior.

Modified:
    lld/trunk/COFF/PDB.cpp
    lld/trunk/test/COFF/pdb-unknown-subsection.s

Modified: lld/trunk/COFF/PDB.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/PDB.cpp?rev=363724&r1=363723&r2=363724&view=diff
==============================================================================
--- lld/trunk/COFF/PDB.cpp (original)
+++ lld/trunk/COFF/PDB.cpp Tue Jun 18 12:41:25 2019
@@ -1002,6 +1002,11 @@ void DebugSHandler::handleDebugS(lld::co
   ExitOnErr(Reader.readArray(Subsections, RelocatedDebugContents.size()));
 
   for (const DebugSubsectionRecord &SS : Subsections) {
+    // Ignore subsections with the 'ignore' bit. Some versions of the Visual C++
+    // runtime have subsections with this bit set.
+    if (uint32_t(SS.kind()) & codeview::SubsectionIgnoreFlag)
+      continue;
+
     switch (SS.kind()) {
     case DebugSubsectionKind::StringTable: {
       assert(!CVStrTab.valid() &&

Modified: lld/trunk/test/COFF/pdb-unknown-subsection.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/COFF/pdb-unknown-subsection.s?rev=363724&r1=363723&r2=363724&view=diff
==============================================================================
--- lld/trunk/test/COFF/pdb-unknown-subsection.s (original)
+++ lld/trunk/test/COFF/pdb-unknown-subsection.s Tue Jun 18 12:41:25 2019
@@ -6,7 +6,9 @@
 # RUN: lld-link -subsystem:console -debug -nodefaultlib -entry:foo -out:%t.exe -pdb:%t.pdb %t.obj 2>&1 | FileCheck %s --check-prefix=WARNING
 # RUN: llvm-pdbutil dump -symbols %t.pdb | FileCheck %s
 
+# WARNING-NOT: ignoring unknown
 # WARNING: ignoring unknown debug$S subsection kind 0xFF
+# WARNING-NOT: ignoring unknown
 
 # CHECK:                           Symbols
 # CHECK:        4 | S_COMPILE3 [size = 52]
@@ -44,3 +46,15 @@ ret
 	.long	0xFF # Unknown subsection kind
 	.long	4           # Subsection size
 	.long  0
+	.long	0x800000F1 # Unknown subsection kind
+	.long	4           # Subsection size
+	.long  0
+	.long	0x800000F2 # Unknown subsection kind
+	.long	4           # Subsection size
+	.long  0
+	.long	0x800000F3 # Unknown subsection kind
+	.long	4           # Subsection size
+	.long  0
+	.long	0x800000F4 # Unknown subsection kind
+	.long	4           # Subsection size
+	.long  0