[DebugInfo] Generate debug information for labels. (Fix PR37395)

Generate DILabel metadata and call llvm.dbg.label after label
statement to associate the metadata with the label.

After fixing PR37395.
After fixing problems in LiveDebugVariables.

Differential Revision: https://reviews.llvm.org/D45045

llvm-svn: 341519

clang/lib/CodeGen/CGDebugInfo.cpp

@@ -3769,6 +3769,32 @@ CGDebugInfo::EmitDeclareOfAutoVariable(const VarDecl *VD, llvm::Value *Storage,
   return EmitDeclare(VD, Storage, llvm::None, Builder);
 }
 
+void CGDebugInfo::EmitLabel(const LabelDecl *D, CGBuilderTy &Builder) {
+  assert(DebugKind >= codegenoptions::LimitedDebugInfo);
+  assert(!LexicalBlockStack.empty() && "Region stack mismatch, stack empty!");
+
+  if (D->hasAttr<NoDebugAttr>())
+    return;
+
+  auto *Scope = cast<llvm::DIScope>(LexicalBlockStack.back());
+  llvm::DIFile *Unit = getOrCreateFile(D->getLocation());
+
+  // Get location information.
+  unsigned Line = getLineNumber(D->getLocation());
+  unsigned Column = getColumnNumber(D->getLocation());
+
+  StringRef Name = D->getName();
+
+  // Create the descriptor for the label.
+  auto *L =
+      DBuilder.createLabel(Scope, Name, Unit, Line, CGM.getLangOpts().Optimize);
+
+  // Insert an llvm.dbg.label into the current block.
+  DBuilder.insertLabel(L,
+                       llvm::DebugLoc::get(Line, Column, Scope, CurInlinedAt),
+                       Builder.GetInsertBlock());
+}
+
 llvm::DIType *CGDebugInfo::CreateSelfType(const QualType &QualTy,
                                           llvm::DIType *Ty) {
   llvm::DIType *CachedTy = getTypeOrNull(QualTy);

clang/lib/CodeGen/CGDebugInfo.h

@@ -415,6 +415,9 @@ class CGDebugInfo {
                                                    llvm::Value *AI,
                                                    CGBuilderTy &Builder);
 
+  /// Emit call to \c llvm.dbg.label for an label.
+  void EmitLabel(const LabelDecl *D, CGBuilderTy &Builder);
+
   /// Emit call to \c llvm.dbg.declare for an imported variable
   /// declaration in a block.
   void EmitDeclareOfBlockDeclRefVariable(

clang/lib/CodeGen/CGStmt.cpp

@@ -531,6 +531,16 @@ void CodeGenFunction::EmitLabel(const LabelDecl *D) {
   }
 
   EmitBlock(Dest.getBlock());
+
+  // Emit debug info for labels.
+  if (CGDebugInfo *DI = getDebugInfo()) {
+    if (CGM.getCodeGenOpts().getDebugInfo() >=
+        codegenoptions::LimitedDebugInfo) {
+      DI->setLocation(D->getLocation());
+      DI->EmitLabel(D, Builder);
+    }
+  }
+
   incrementProfileCounter(D->getStmt());
 }
 

clang/test/CodeGen/debug-label-inline.c

@@ -0,0 +1,28 @@
+// This test will test the correctness of generating DILabel and
+// llvm.dbg.label when the label is in inlined functions.
+//
+// RUN: %clang_cc1 -O2 %s -o - -emit-llvm -debug-info-kind=limited | FileCheck %s
+inline int f1(int a, int b) {
+  int sum;
+
+top:
+  sum = a + b;
+  return sum;
+}
+
+extern int ga, gb;
+
+int f2(void) {
+  int result;
+
+  result = f1(ga, gb);
+  // CHECK: call void @llvm.dbg.label(metadata [[LABEL_METADATA:!.*]]), !dbg [[LABEL_LOCATION:!.*]]
+
+  return result;
+}
+
+// CHECK: distinct !DISubprogram(name: "f1", {{.*}}, retainedNodes: [[ELEMENTS:!.*]])
+// CHECK: [[ELEMENTS]] = !{{{.*}}, [[LABEL_METADATA]]}
+// CHECK: [[LABEL_METADATA]] = !DILabel({{.*}}, name: "top", {{.*}}, line: 8)
+// CHECK: [[INLINEDAT:!.*]] = distinct !DILocation(line: 18,
+// CHECK: [[LABEL_LOCATION]] = !DILocation(line: 8, {{.*}}, inlinedAt: [[INLINEDAT]])

clang/test/CodeGen/debug-label.c

@@ -0,0 +1,16 @@
+// This test will test the correstness of generating DILabel and
+// llvm.dbg.label for labels.
+//
+// RUN: %clang_cc1 -emit-llvm %s -o - -emit-llvm -debug-info-kind=limited | FileCheck %s
+
+int f1(int a, int b) {
+  int sum;
+
+top:
+  // CHECK: call void @llvm.dbg.label(metadata [[LABEL_METADATA:!.*]]), !dbg [[LABEL_LOCATION:!.*]]
+  sum = a + b;
+  return sum;
+}
+
+// CHECK: [[LABEL_METADATA]] = !DILabel({{.*}}, name: "top", {{.*}}, line: 9)
+// CHECK: [[LABEL_LOCATION]] = !DILocation(line: 9,