[clang][DebugInfo] Allow function-local statics to be scoped within a lexical block (4/5)

[krisb]

Summary

This is a part from D113743 split to make it easier to test and review.

[aprantl]

This looks very good, thanks!

clang/lib/CodeGen/CGDebugInfo.cpp

void CGDebugInfo::collectVarDeclProps(const VarDecl *VD, llvm::DIFile *&Unit,
 
   if (isa<VarTemplateSpecializationDecl>(VD)) {
     llvm::DINodeArray parameterNodes = CollectVarTemplateParams(VD, &*Unit);
     TemplateParameters = parameterNodes.get();
   } else {
     TemplateParameters = nullptr;
   }
 
+  // Get context for static locals (that are technically globals) the same way
+  // we do for "local" locals -- by using current lexical block.
+  if (VD->isStaticLocal()) {
+    assert(!LexicalBlockStack.empty() && "Region stack mismatch, stack empty!");
+    VDContext = LexicalBlockStack.back();
+    return;
+  }
+
   // Since we emit declarations (DW_AT_members) for static members, place the
   // definition of those static members in the namespace they were declared in
   // in the source code (the lexical decl context).
   // FIXME: Generalize this for even non-member global variables where the
   // declaration and definition may have different lexical decl contexts, once
   // we have support for emitting declarations of (non-member) global variables.
   const DeclContext *DC = VD->isStaticDataMember() ? VD->getLexicalDeclContext()
                                                    : VD->getDeclContext();

clang/test/CodeGenCXX/debug-info-static-locals.cpp

+// RUN: %clang_cc1 -triple x86_64-none-linux-gnu -emit-llvm -debug-info-kind=limited %s -o - | FileCheck %s
+
+// Test that static local variables emitted in correct scopes.
+
+void test() {
+  static int bar = 2;
+  {
+    static int bar = 1;
+    {
+      static int bar = 0;
+    }
+  }
+}
+
+// CHECK: [[FS_GVE:![0-9]+]] = !DIGlobalVariableExpression(var: [[FS_GV:![0-9]+]]
+// CHECK: [[FS_GV]] = distinct !DIGlobalVariable(name: "bar", scope: [[FSCOPE:![0-9]+]]
+// CHECK: [[FSCOPE]] = distinct !DISubprogram(name: "test"
+// CHECK-SAME:                                localDecls: [[FS_DECLS:![0-9]+]]
+// CHECK: [[FS_DECLS]] = !{[[FS_GVE]]}
+// CHECK: [[LB1_GVE:![0-9]+]] = !DIGlobalVariableExpression(var: [[LB1_GV:![0-9]+]]
+// CHECK: [[LB1_GV]] = distinct !DIGlobalVariable(name: "bar", scope: [[LB1SCOPE:![0-9]+]]
+// CHECK: [[LB1SCOPE]] = distinct !DILexicalBlock(scope: [[FSCOPE]]
+// CHECK-SAME:                                    localDecls: [[LB1_DECLS:![0-9]+]]
+// CHECK: [[LB1_DECLS]] = !{[[LB1_GVE]]}
+// CHECK: [[LB2_GVE:![0-9]+]] = !DIGlobalVariableExpression(var: [[LB2_GV:![0-9]+]]
+// CHECK: [[LB2_GV]] = distinct !DIGlobalVariable(name: "bar", scope: [[LB2SCOPE:![0-9]+]]
+// CHECK: [[LB2SCOPE]] = distinct !DILexicalBlock(scope: [[LB1SCOPE]]
+// CHECK-SAME:                                    localDecls: [[LB2_DECLS:![0-9]+]]
+// CHECK: [[LB2_DECLS]] = !{[[LB2_GVE]]}