[llvm] [DebugInfo] Emit skeleton to avoid mismatching inlining flags (PR #153568)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-debuginfo

Author: Qiu Chaofan (ecnelises)

<details>
<summary>Changes</summary>

This actually reverts 418120556398c01550d42500d56e6d328290185b.

The original commit omits unit with all symbols inlined into current one, which leads to crash when a module using split-dwarf inlined a function from another module with mismatched split-dwarf-inlining option. This revert guarantees that DIEs are created in both DWO and the skeleton sections whenever split-dwarf is active.

---
Full diff: https://github.com/llvm/llvm-project/pull/153568.diff


2 Files Affected:

- (modified) llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (+8-12) 
- (modified) llvm/test/DebugInfo/X86/split-dwarf-omit-empty.ll (+1-1) 


``````````diff
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index c27f100775625..afa8511981e23 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -558,18 +558,14 @@ void DwarfDebug::constructAbstractSubprogramScopeDIE(DwarfCompileUnit &SrcCU,
 
   // Find the subprogram's DwarfCompileUnit in the SPMap in case the subprogram
   // was inlined from another compile unit.
-  if (useSplitDwarf() && !shareAcrossDWOCUs() && !SP->getUnit()->getSplitDebugInlining())
-    // Avoid building the original CU if it won't be used
-    SrcCU.constructAbstractSubprogramScopeDIE(Scope);
-  else {
-    auto &CU = getOrCreateDwarfCompileUnit(SP->getUnit());
-    if (auto *SkelCU = CU.getSkeleton()) {
-      (shareAcrossDWOCUs() ? CU : SrcCU)
-          .constructAbstractSubprogramScopeDIE(Scope);
-      if (CU.getCUNode()->getSplitDebugInlining())
-        SkelCU->constructAbstractSubprogramScopeDIE(Scope);
-    } else
-      CU.constructAbstractSubprogramScopeDIE(Scope);
+  auto &CU = getOrCreateDwarfCompileUnit(SP->getUnit());
+  if (auto *SkelCU = CU.getSkeleton()) {
+    (shareAcrossDWOCUs() ? CU : SrcCU)
+        .constructAbstractSubprogramScopeDIE(Scope);
+    if (CU.getCUNode()->getSplitDebugInlining())
+      SkelCU->constructAbstractSubprogramScopeDIE(Scope);
+  } else {
+    CU.constructAbstractSubprogramScopeDIE(Scope);
   }
 }
 
diff --git a/llvm/test/DebugInfo/X86/split-dwarf-omit-empty.ll b/llvm/test/DebugInfo/X86/split-dwarf-omit-empty.ll
index f4cee1ec78b1d..95aae44b679d5 100644
--- a/llvm/test/DebugInfo/X86/split-dwarf-omit-empty.ll
+++ b/llvm/test/DebugInfo/X86/split-dwarf-omit-empty.ll
@@ -38,7 +38,7 @@ entry:
 !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 5.0.0 (trunk 304054) (llvm/trunk 304080)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false)
 !1 = !DIFile(filename: "a.cpp", directory: "/usr/local/google/home/blaikie/dev/scratch")
 !2 = !{}
-!3 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !4, producer: "clang version 5.0.0 (trunk 304054) (llvm/trunk 304080)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false)
+!3 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !4, producer: "clang version 5.0.0 (trunk 304054) (llvm/trunk 304080)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: true)
 !4 = !DIFile(filename: "b.cpp", directory: "/usr/local/google/home/blaikie/dev/scratch")
 !5 = !{!"clang version 5.0.0 (trunk 304054) (llvm/trunk 304080)"}
 !6 = !{i32 2, !"Dwarf Version", i32 4}

``````````

</details>


https://github.com/llvm/llvm-project/pull/153568