[codeview] Shrink inlined call site line info tables

For a fully inlined call chain like a -> b -> c -> d, we were emitting
line info for 'd' 3 separate times: once for d's actual InlineSite line
table, and twice for 'b' and 'c'. This is particularly inefficient when
all these functions are in different headers, because now we need to
encode the file change. Windbg was coping with our suboptimal output, so
this should not be noticeable from the debugger.

llvm-svn: 275502

1 files changed, 11 insertions, 5 deletions

diff --git a/llvm/lib/MC/MCCodeView.cpp b/llvm/lib/MC/MCCodeView.cpp
index d3f2aa2a80c..65cff41abeb 100644
--- a/llvm/lib/MC/MCCodeView.cpp
+++ b/llvm/lib/MC/MCCodeView.cpp
@@ -302,7 +302,7 @@ void CodeViewContext::encodeInlineLineTable(MCAsmLayout &Layout,
   StartLoc.setFileNum(Frag.StartFileId);
   StartLoc.setLine(Frag.StartLineNum);
   const MCCVLineEntry *LastLoc = &StartLoc;
-  bool WithinFunction = true;
+  bool HaveOpenRange = false;
 
   SmallVectorImpl<char> &Buffer = Frag.getContents();
   Buffer.clear(); // Clear old contents if we went through relaxation.
@@ -310,16 +310,22 @@ void CodeViewContext::encodeInlineLineTable(MCAsmLayout &Layout,
     if (!InlinedFuncIds.count(Loc.getFunctionId())) {
       // We've hit a cv_loc not attributed to this inline call site. Use this
       // label to end the PC range.
-      if (WithinFunction) {
+      if (HaveOpenRange) {
         unsigned Length =
             computeLabelDiff(Layout, LastLoc->getLabel(), Loc.getLabel());
         compressAnnotation(BinaryAnnotationsOpCode::ChangeCodeLength, Buffer);
         compressAnnotation(Length, Buffer);
       }
-      WithinFunction = false;
+      HaveOpenRange = false;
       continue;
     }
-    WithinFunction = true;
+
+    // If we've already opened the function and we're at an indirectly inlined
+    // location, continue until the next directly inlined location.
+    bool DirectlyInlined = Loc.getFunctionId() == Frag.SiteFuncId;
+    if (!DirectlyInlined && HaveOpenRange)
+      continue;
+    HaveOpenRange = true;
 
     if (Loc.getFileNum() != LastLoc->getFileNum()) {
       // File ids are 1 based, and each file checksum table entry is 8 bytes
@@ -358,7 +364,7 @@ void CodeViewContext::encodeInlineLineTable(MCAsmLayout &Layout,
     LastLoc = &Loc;
   }
 
-  assert(WithinFunction);
+  assert(HaveOpenRange);
 
   unsigned EndSymLength =
       computeLabelDiff(Layout, LastLoc->getLabel(), Frag.getFnEndSym());