From 11ebe64f8b742a1ba4bc121b1b8994cbb315d851 Mon Sep 17 00:00:00 2001
From: Hsiangkai Wang <hsiangkai@gmail.com>
Date: Wed, 26 Sep 2018 22:18:45 +0000
Subject: [PATCH] [DebugInfo] Generate debug information for labels.

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.
After fixing NULL symbol problems in AddressPool when enabling
split-dwarf-file.

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

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@343148 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/CGDebugInfo.cpp       | 26 ++++++++++++++++++++++++++
 lib/CodeGen/CGDebugInfo.h         |  3 +++
 lib/CodeGen/CGStmt.cpp            | 10 ++++++++++
 test/CodeGen/debug-label-inline.c | 28 ++++++++++++++++++++++++++++
 test/CodeGen/debug-label.c        | 16 ++++++++++++++++
 5 files changed, 83 insertions(+)
 create mode 100644 test/CodeGen/debug-label-inline.c
 create mode 100644 test/CodeGen/debug-label.c

diff --git a/lib/CodeGen/CGDebugInfo.cpp b/lib/CodeGen/CGDebugInfo.cpp
index 7d6eb83f12..da231c9089 100644
--- a/lib/CodeGen/CGDebugInfo.cpp
+++ b/lib/CodeGen/CGDebugInfo.cpp
@@ -3767,6 +3767,32 @@ 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);
diff --git a/lib/CodeGen/CGDebugInfo.h b/lib/CodeGen/CGDebugInfo.h
index 8641c2d896..9e771072aa 100644
--- a/lib/CodeGen/CGDebugInfo.h
+++ b/lib/CodeGen/CGDebugInfo.h
@@ -415,6 +415,9 @@ public:
                                                    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(
diff --git a/lib/CodeGen/CGStmt.cpp b/lib/CodeGen/CGStmt.cpp
index 09c322a852..0bcf3554dc 100644
--- a/lib/CodeGen/CGStmt.cpp
+++ b/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());
 }
 
diff --git a/test/CodeGen/debug-label-inline.c b/test/CodeGen/debug-label-inline.c
new file mode 100644
index 0000000000..c0b089aad8
--- /dev/null
+++ b/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]])
diff --git a/test/CodeGen/debug-label.c b/test/CodeGen/debug-label.c
new file mode 100644
index 0000000000..20efa49b0a
--- /dev/null
+++ b/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,
-- 
2.40.0