[llvm] Revert "[SelectionDAG] Fix null pointer dereference in resolveDanglingDebugInfo" (PR #180352)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-selectiondag

@llvm/pr-subscribers-backend-x86

Author: Qinkun Bao (qinkunbao)

<details>
<summary>Changes</summary>

Reverts llvm/llvm-project#<!-- -->174341

Break https://lab.llvm.org/buildbot/#/builders/24/builds/17324

---
Full diff: https://github.com/llvm/llvm-project/pull/180352.diff


2 Files Affected:

- (modified) llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp (+1-1) 
- (removed) llvm/test/CodeGen/X86/selectiondag-dbgvalue-null-crash.ll (-46) 


``````````diff
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 3beea7221fefe..78b725f1455cc 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -1505,6 +1505,7 @@ void SelectionDAGBuilder::resolveDanglingDebugInfo(const Value *V,
   DanglingDebugInfoVector &DDIV = DanglingDbgInfoIt->second;
   for (auto &DDI : DDIV) {
     DebugLoc DL = DDI.getDebugLoc();
+    unsigned ValSDNodeOrder = Val.getNode()->getIROrder();
     unsigned DbgSDNodeOrder = DDI.getSDNodeOrder();
     DILocalVariable *Variable = DDI.getVariable();
     DIExpression *Expr = DDI.getExpression();
@@ -1518,7 +1519,6 @@ void SelectionDAGBuilder::resolveDanglingDebugInfo(const Value *V,
       // in the first place we should not be more successful here). Unless we
       // have some test case that prove this to be correct we should avoid
       // calling EmitFuncArgumentDbgValue here.
-      unsigned ValSDNodeOrder = Val.getNode()->getIROrder();
       if (!EmitFuncArgumentDbgValue(V, Variable, Expr, DL,
                                     FuncArgumentDbgValueKind::Value, Val)) {
         LLVM_DEBUG(dbgs() << "Resolve dangling debug info for "
diff --git a/llvm/test/CodeGen/X86/selectiondag-dbgvalue-null-crash.ll b/llvm/test/CodeGen/X86/selectiondag-dbgvalue-null-crash.ll
deleted file mode 100644
index 99e0bd6ee3f23..0000000000000
--- a/llvm/test/CodeGen/X86/selectiondag-dbgvalue-null-crash.ll
+++ /dev/null
@@ -1,46 +0,0 @@
-; Test that the code generation works correctly on Linux
-; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
-; Darwin currently crashes due to an unrelated DWARF generation bug
-; RUN: not --crash llc < %s -mtriple=x86_64-apple-darwin
-
-; Regression test for SelectionDAG::resolveDanglingDebugInfo crash when
-; handling aggregate types with nested empty structs.
-;
-; This test verifies the fix for null pointer dereference in
-; SelectionDAG::resolveDanglingDebugInfo. The original issue occurred when
-; insertvalue operations on aggregate types containing nested empty structs
-; produced SDValue nodes with null pointers.
-;
-; NOTE: This test case also revealed an unrelated Darwin-specific crash in
-;       DwarfCompileUnit::constructSubprogramScopeDIE during DWARF generation.
-;
-; FIXME: Investigate and fix the Darwin crash separately. The crash occurs in
-;        the Assembly Printer pass when generating DWARF debug info for
-;        functions with aggregate types containing nested empty structs.
-
-; CHECK-LABEL: test_empty_struct_debug:
-; CHECK: retq
-
-define void @test_empty_struct_debug() !dbg !4 {
-entry:
-  %tmp = alloca { { i1, {} }, ptr, { { {} }, { {} } }, i64 }, align 8
-    #dbg_value({ { {} }, { {} } } zeroinitializer, !5, !DIExpression(), !6)
-    #dbg_value(i64 2, !7, !DIExpression(), !6)
-  %0 = insertvalue { { i1, {} }, ptr, { { {} }, { {} } }, i64 } { { i1, {} } zeroinitializer, ptr null, { { {} }, { {} } } zeroinitializer, i64 2 }, ptr null, 1, !dbg !6
-  %1 = insertvalue { { i1, {} }, ptr, { { {} }, { {} } }, i64 } %0, { i1, {} } zeroinitializer, 0, !dbg !8
-  store { { i1, {} }, ptr, { { {} }, { {} } }, i64 } %1, ptr %tmp, align 8
-  ret void
-}
-
-!llvm.dbg.cu = !{!0}
-!llvm.module.flags = !{!2, !3}
-
-!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, isOptimized: false, runtimeVersion: 0, emissionKind: LineTablesOnly)
-!1 = !DIFile(filename: "test_selectiondag.cpp", directory: "/home/AnonTokyo/documents/llvm-project/temp")
-!2 = !{i32 2, !"Debug Info Version", i32 3}
-!3 = !{i32 2, !"Dwarf Version", i32 4}
-!4 = distinct !DISubprogram(name: "test_empty_struct_debug", scope: !1, file: !1, line: 1, scopeLine: 1, spFlags: DISPFlagDefinition, unit: !0)
-!5 = !DILocalVariable(name: "v1", scope: !4, file: !1, line: 2)
-!6 = !DILocation(line: 2, column: 1, scope: !4)
-!7 = !DILocalVariable(name: "v2", scope: !4, file: !1, line: 3)
-!8 = !DILocation(line: 3, column: 1, scope: !4)

``````````

</details>


https://github.com/llvm/llvm-project/pull/180352