[codeview] Ignore DBG_VALUEs when choosing a BB start source loc

When the first instruction of a basic block has no location (consider a
LEA materializing the address of an alloca for a call), we want to start
the line table for the block with the first valid source location in the
block.  We need to ignore DBG_VALUE instructions during this scan to get
decent line tables.

llvm-svn: 309628

1 files changed, 2 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
index c9686cccfdf..38ae15cbd98 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -2157,6 +2157,8 @@ void CodeViewDebug::beginInstruction(const MachineInstr *MI) {
   DebugLoc DL = MI->getDebugLoc();
   if (!DL && MI->getParent() != PrevInstBB) {
     for (const auto &NextMI : *MI->getParent()) {
+      if (NextMI.isDebugValue())
+        continue;
       DL = NextMI.getDebugLoc();
       if (DL)
         break;