[llvm] r311217 - Filter out non-constant DIGlobalVariableExpressions reachable via the CU

[Adrian Prantl via llvm-commits]

Author: adrian
Date: Fri Aug 18 18:15:06 2017
New Revision: 311217

URL: http://llvm.org/viewvc/llvm-project?rev=311217&view=rev
Log:
Filter out non-constant DIGlobalVariableExpressions reachable via the CU

They won't affect the DWARF output, but they will mess with the
sorting of the fragments. This fixes the crash reported in PR34159.

https://bugs.llvm.org/show_bug.cgi?id=34159

Modified:
    llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
    llvm/trunk/test/DebugInfo/X86/split-global.ll

Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=311217&r1=311216&r2=311217&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Fri Aug 18 18:15:06 2017
@@ -592,8 +592,15 @@ void DwarfDebug::beginModule() {
     DwarfCompileUnit &CU = getOrCreateDwarfCompileUnit(CUNode);
 
     // Global Variables.
-    for (auto *GVE : CUNode->getGlobalVariables())
-      GVMap[GVE->getVariable()].push_back({nullptr, GVE->getExpression()});
+    for (auto *GVE : CUNode->getGlobalVariables()) {
+      // Don't bother adding DIGlobalVariableExpressions listed in the CU if we
+      // already know about the variable and it isn't adding a constant
+      // expression.
+      auto &GVMapEntry = GVMap[GVE->getVariable()];
+      auto *Expr = GVE->getExpression();
+      if (!GVMapEntry.size() || (Expr && Expr->isConstant()))
+        GVMapEntry.push_back({nullptr, Expr});
+    }
     DenseSet<DIGlobalVariable *> Processed;
     for (auto *GVE : CUNode->getGlobalVariables()) {
       DIGlobalVariable *GV = GVE->getVariable();

Modified: llvm/trunk/test/DebugInfo/X86/split-global.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/split-global.ll?rev=311217&r1=311216&r2=311217&view=diff
==============================================================================
--- llvm/trunk/test/DebugInfo/X86/split-global.ll (original)
+++ llvm/trunk/test/DebugInfo/X86/split-global.ll Fri Aug 18 18:15:06 2017
@@ -39,7 +39,7 @@ target triple = "x86_64-apple-macosx10.1
 !1 = distinct !DICompileUnit(language: DW_LANG_C99, file: !2, producer: "clang", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, globals: !4)
 !2 = !DIFile(filename: "g.c", directory: "/")
 !3 = !{}
-!4 = !{!12, !13, !14, !15, !17, !18}
+!4 = !{!12, !13, !14, !15, !17, !18, !20}
 !5 = distinct !DICompositeType(tag: DW_TAG_structure_type, file: !2, line: 1, size: 64, elements: !6)
 !6 = !{!7, !9}
 !7 = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: !5, file: !2, line: 1, baseType: !8, size: 32)
@@ -58,3 +58,4 @@ target triple = "x86_64-apple-macosx10.1
 !18 = !DIGlobalVariableExpression(var: !19, expr: !DIExpression(DW_OP_constu, 2,
                                              DW_OP_stack_value, DW_OP_LLVM_fragment, 32, 32))
 !19 = distinct !DIGlobalVariable(name: "full_const", scope: !1, file: !2, line: 1, type: !5, isLocal: false, isDefinition: true)
+!20 = !DIGlobalVariableExpression(var: !0)