Emit line numbers in CodeView for trailing (after ret) blocks from inlined functions

dpaoliello · dpaoliello · commit f2f36c9b2955 · 2023-09-06T10:19:30.000-07:00
Issue Details: When building up line information for CodeView debug info, LLVM attempts to gather the "range" of instructions within a function as these are printed together in a single record. If there is an inlined function, then those lines are attributed to the original function to enable generating `S_INLINESITE` records. However, this thus requires there to be instructions from the inlining function after the inlined function otherwise the instruction range would not include the inlined function. Fix Details: Include any inlined functions when finding the extent of a function in `getFunctionLineEntries` Reviewed By: rnk Differential Revision: https://reviews.llvm.org/D159226
diff --git a/lld/test/COFF/symbolizer-line-numbers.s b/lld/test/COFF/symbolizer-line-numbers.s
@@ -62,16 +62,16 @@
 # CHECK:      f1
 # CHECK-NEXT: t.cpp:2:0
 # CHECK-NEXT: f2(int)
-# CHECK-NEXT: t.cpp:6:3
+# CHECK-NEXT: t.cpp:6:10
 	.cv_inline_site_id 2 within 1 inlined_at 1 6 10
 	.cv_loc	2 1 2 13                        # t.cpp:2:13
                                         # kill: def $ecx killed $ecx def $rcx
 	leal	1(%rcx), %eax
 .Ltmp1:
-	.cv_loc	1 1 6 3                         # t.cpp:6:3
-	retq
 # CHECK:      f2(int)
 # CHECK-NEXT: t.cpp:6:3
+	.cv_loc	1 1 6 3                         # t.cpp:6:3
+	retq
 .Ltmp2:
 .Lfunc_end1:
                                         # -- End function
diff --git a/llvm/include/llvm/MC/MCCodeView.h b/llvm/include/llvm/MC/MCCodeView.h
@@ -182,6 +182,7 @@ class CodeViewContext {
   std::vector<MCCVLoc> getFunctionLineEntries(unsigned FuncId);
 
   std::pair<size_t, size_t> getLineExtent(unsigned FuncId);
+  std::pair<size_t, size_t> getLineExtentIncludingInlinees(unsigned FuncId);
 
   ArrayRef<MCCVLoc> getLinesForExtent(size_t L, size_t R);
 
diff --git a/llvm/lib/MC/MCCodeView.cpp b/llvm/lib/MC/MCCodeView.cpp
@@ -275,32 +275,35 @@ void CodeViewContext::addLineEntry(const MCCVLoc &LineEntry) {
 std::vector<MCCVLoc>
 CodeViewContext::getFunctionLineEntries(unsigned FuncId) {
   std::vector<MCCVLoc> FilteredLines;
-  auto I = MCCVLineStartStop.find(FuncId);
-  if (I != MCCVLineStartStop.end()) {
-    MCCVFunctionInfo *SiteInfo = getCVFunctionInfo(FuncId);
-    for (size_t Idx = I->second.first, End = I->second.second; Idx != End;
-         ++Idx) {
-      unsigned LocationFuncId = MCCVLines[Idx].getFunctionId();
-      if (LocationFuncId == FuncId) {
-        // This was a .cv_loc directly for FuncId, so record it.
-        FilteredLines.push_back(MCCVLines[Idx]);
-      } else {
-        // Check if the current location is inlined in this function. If it is,
-        // synthesize a statement .cv_loc at the original inlined call site.
-        auto I = SiteInfo->InlinedAtMap.find(LocationFuncId);
-        if (I != SiteInfo->InlinedAtMap.end()) {
-          MCCVFunctionInfo::LineInfo &IA = I->second;
-          // Only add the location if it differs from the previous location.
-          // Large inlined calls will have many .cv_loc entries and we only need
-          // one line table entry in the parent function.
-          if (FilteredLines.empty() ||
-              FilteredLines.back().getFileNum() != IA.File ||
-              FilteredLines.back().getLine() != IA.Line ||
-              FilteredLines.back().getColumn() != IA.Col) {
-            FilteredLines.push_back(MCCVLoc(
-                MCCVLines[Idx].getLabel(),
-                FuncId, IA.File, IA.Line, IA.Col, false, false));
-          }
+  size_t LocBegin;
+  size_t LocEnd;
+  std::tie(LocBegin, LocEnd) = getLineExtentIncludingInlinees(FuncId);
+  if (LocBegin >= LocEnd) {
+    return FilteredLines;
+  }
+
+  MCCVFunctionInfo *SiteInfo = getCVFunctionInfo(FuncId);
+  for (size_t Idx = LocBegin; Idx != LocEnd; ++Idx) {
+    unsigned LocationFuncId = MCCVLines[Idx].getFunctionId();
+    if (LocationFuncId == FuncId) {
+      // This was a .cv_loc directly for FuncId, so record it.
+      FilteredLines.push_back(MCCVLines[Idx]);
+    } else {
+      // Check if the current location is inlined in this function. If it is,
+      // synthesize a statement .cv_loc at the original inlined call site.
+      auto I = SiteInfo->InlinedAtMap.find(LocationFuncId);
+      if (I != SiteInfo->InlinedAtMap.end()) {
+        MCCVFunctionInfo::LineInfo &IA = I->second;
+        // Only add the location if it differs from the previous location.
+        // Large inlined calls will have many .cv_loc entries and we only need
+        // one line table entry in the parent function.
+        if (FilteredLines.empty() ||
+            FilteredLines.back().getFileNum() != IA.File ||
+            FilteredLines.back().getLine() != IA.Line ||
+            FilteredLines.back().getColumn() != IA.Col) {
+          FilteredLines.push_back(MCCVLoc(MCCVLines[Idx].getLabel(), FuncId,
+                                          IA.File, IA.Line, IA.Col, false,
+                                          false));
         }
       }
     }
@@ -316,6 +319,26 @@ std::pair<size_t, size_t> CodeViewContext::getLineExtent(unsigned FuncId) {
   return I->second;
 }
 
+std::pair<size_t, size_t>
+CodeViewContext::getLineExtentIncludingInlinees(unsigned FuncId) {
+  size_t LocBegin;
+  size_t LocEnd;
+  std::tie(LocBegin, LocEnd) = getLineExtent(FuncId);
+
+  // Include all child inline call sites in our extent.
+  MCCVFunctionInfo *SiteInfo = getCVFunctionInfo(FuncId);
+  if (SiteInfo) {
+    for (auto &KV : SiteInfo->InlinedAtMap) {
+      unsigned ChildId = KV.first;
+      auto Extent = getLineExtent(ChildId);
+      LocBegin = std::min(LocBegin, Extent.first);
+      LocEnd = std::max(LocEnd, Extent.second);
+    }
+  }
+
+  return {LocBegin, LocEnd};
+}
+
 ArrayRef<MCCVLoc> CodeViewContext::getLinesForExtent(size_t L, size_t R) {
   if (R <= L)
     return std::nullopt;
@@ -463,16 +486,7 @@ void CodeViewContext::encodeInlineLineTable(MCAsmLayout &Layout,
                                             MCCVInlineLineTableFragment &Frag) {
   size_t LocBegin;
   size_t LocEnd;
-  std::tie(LocBegin, LocEnd) = getLineExtent(Frag.SiteFuncId);
-
-  // Include all child inline call sites in our .cv_loc extent.
-  MCCVFunctionInfo *SiteInfo = getCVFunctionInfo(Frag.SiteFuncId);
-  for (auto &KV : SiteInfo->InlinedAtMap) {
-    unsigned ChildId = KV.first;
-    auto Extent = getLineExtent(ChildId);
-    LocBegin = std::min(LocBegin, Extent.first);
-    LocEnd = std::max(LocEnd, Extent.second);
-  }
+  std::tie(LocBegin, LocEnd) = getLineExtentIncludingInlinees(Frag.SiteFuncId);
 
   if (LocBegin >= LocEnd)
     return;
@@ -507,6 +521,8 @@ void CodeViewContext::encodeInlineLineTable(MCAsmLayout &Layout,
   LastSourceLoc.File = Frag.StartFileId;
   LastSourceLoc.Line = Frag.StartLineNum;
 
+  MCCVFunctionInfo *SiteInfo = getCVFunctionInfo(Frag.SiteFuncId);
+
   SmallVectorImpl<char> &Buffer = Frag.getContents();
   Buffer.clear(); // Clear old contents if we went through relaxation.
   for (const MCCVLoc &Loc : Locs) {
diff --git a/llvm/test/DebugInfo/COFF/trailing-inlined-function.s b/llvm/test/DebugInfo/COFF/trailing-inlined-function.s
