1 files changed, 18 insertions, 4 deletions

diff --git a/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
index e94616fd59006..a81d56e9618bf 100644
--- a/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -365,7 +365,7 @@ static void addLocIfNotPresent(SmallVectorImpl<const DILocation *> &Locs,
 void CodeViewDebug::maybeRecordLocation(const DebugLoc &DL,
                                         const MachineFunction *MF) {
   // Skip this instruction if it has the same location as the previous one.
-  if (DL == CurFn->LastLoc)
+  if (!DL || DL == PrevInstLoc)
     return;
 
   const DIScope *Scope = DL.get()->getScope();
@@ -385,11 +385,11 @@ void CodeViewDebug::maybeRecordLocation(const DebugLoc &DL,
   if (!CurFn->HaveLineInfo)
     CurFn->HaveLineInfo = true;
   unsigned FileId = 0;
-  if (CurFn->LastLoc.get() && CurFn->LastLoc->getFile() == DL->getFile())
+  if (PrevInstLoc.get() && PrevInstLoc->getFile() == DL->getFile())
     FileId = CurFn->LastFileId;
   else
     FileId = CurFn->LastFileId = maybeRecordFile(DL->getFile());
-  CurFn->LastLoc = DL;
+  PrevInstLoc = DL;
 
   unsigned FuncId = CurFn->FuncId;
   if (const DILocation *SiteLoc = DL->getInlinedAt()) {
@@ -2150,9 +2150,23 @@ void CodeViewDebug::beginInstruction(const MachineInstr *MI) {
   if (!Asm || !CurFn || MI->isDebugValue() ||
       MI->getFlag(MachineInstr::FrameSetup))
     return;
+
+  // If the first instruction of a new MBB has no location, find the first
+  // instruction with a location and use that.
   DebugLoc DL = MI->getDebugLoc();
-  if (DL == PrevInstLoc || !DL)
+  if (!DL && MI->getParent() != PrevInstBB) {
+    for (const auto &NextMI : *MI->getParent()) {
+      DL = NextMI.getDebugLoc();
+      if (DL)
+        break;
+    }
+  }
+  PrevInstBB = MI->getParent();
+
+  // If we still don't have a debug location, don't record a location.
+  if (!DL)
     return;
+
   maybeRecordLocation(DL, Asm->MF);
 }