This patch adds a new Clang compiler flag "-gline-tables-only".

It reduces the amount of emitted debug information:
1) DIEs in .debug_info have types DW_TAG_compile_unit, DW_TAG_subprogram,
DW_TAG_inlined_subroutine (for opt builds) and DW_TAG_lexical_block only.
2) .debug_str contains only function names.
3) No debug data for types/namespaces/variables is emitted.
4) The data in .debug_line is enough to produce valid stack traces with
function names and line numbers.

Reviewed by Eric Christopher.

llvm-svn: 156160

4 files changed, 72 insertions, 0 deletions

diff --git a/clang/test/CodeGen/debug-info-gline-tables-only.c b/clang/test/CodeGen/debug-info-gline-tables-only.c
new file mode 100644
index 00000000000..067d8e77218
--- /dev/null
+++ b/clang/test/CodeGen/debug-info-gline-tables-only.c
@@ -0,0 +1,33 @@
+// RUN: %clang_cc1 %s -gline-tables-only -S -emit-llvm -o - | FileCheck %s
+// Checks that clang with "-gline-tables-only" doesn't emit debug info
+// for variables and types.
+
+// CHECK-NOT: DW_TAG_variable
+int global = 42;
+
+// CHECK-NOT: DW_TAG_typedef
+// CHECK-NOT: DW_TAG_const_type
+// CHECK-NOT: DW_TAG_pointer_type
+// CHECK-NOT: DW_TAG_array_type
+typedef const char* constCharPtrArray[10];
+
+// CHECK-NOT: DW_TAG_structure_type
+struct S {
+  // CHECK-NOT: DW_TAG_member
+  char a;
+  double b;
+  constCharPtrArray c;
+};
+
+// CHECK-NOT: DW_TAG_enumerator
+// CHECK-NOT: DW_TAG_enumeration_type
+enum E { ZERO = 0, ONE = 1 };
+
+// CHECK-NOT: DW_TAG_arg_variable
+int sum(int p, int q) {
+  // CHECK-NOT: DW_TAG_auto_variable
+  int r = p + q;
+  struct S s;
+  enum E e;
+  return r;
+}
diff --git a/clang/test/CodeGen/debug-info-gline-tables-only2.c b/clang/test/CodeGen/debug-info-gline-tables-only2.c
new file mode 100644
index 00000000000..8e9cc64e0d6
--- /dev/null
+++ b/clang/test/CodeGen/debug-info-gline-tables-only2.c
@@ -0,0 +1,13 @@
+// RUN: %clang_cc1 %s -gline-tables-only -S -emit-llvm -o - | FileCheck %s
+// Checks that clang with "-gline-tables-only" emits metadata for
+// compile unit, subprogram and file.
+
+int main() {
+  // CHECK: ret i32 0, !dbg
+  return 0;
+}
+
+// CHECK: !llvm.dbg.cu = !{!0}
+// CHECK: DW_TAG_compile_unit
+// CHECK: {{.*main.* DW_TAG_subprogram}}
+// CHECK: DW_TAG_file_type
diff --git a/clang/test/CodeGenCXX/debug-info-gline-tables-only.cpp b/clang/test/CodeGenCXX/debug-info-gline-tables-only.cpp
new file mode 100644
index 00000000000..8d2e63d6777
--- /dev/null
+++ b/clang/test/CodeGenCXX/debug-info-gline-tables-only.cpp
@@ -0,0 +1,21 @@
+// RUN: %clang_cc1 %s -O0 -gline-tables-only -S -emit-llvm -o - | FileCheck %s
+// Checks that clang with "-gline-tables-only" doesn't emit debug info
+// for variables and types.
+
+// CHECK-NOT: DW_TAG_namespace
+namespace NS {
+// CHECK-NOT: DW_TAG_class_type
+// CHECK-NOT: DW_TAG_friend
+class C { friend class D; };
+class D {};
+// CHECK-NOT: DW_TAG_inheritance
+class E : public C {
+  // CHECK-NOT: DW_TAG_reference type
+  void x(const D& d);
+};
+}
+
+// CHECK-NOT: DW_TAG_variable
+NS::C c;
+NS::D d;
+NS::E e;
diff --git a/clang/test/Driver/debug-options.c b/clang/test/Driver/debug-options.c
index 5dad8e93824..b0ad2857357 100644
--- a/clang/test/Driver/debug-options.c
+++ b/clang/test/Driver/debug-options.c
@@ -7,6 +7,8 @@
 // RUN: %clang -### -c -ganything %s 2>&1 | FileCheck -check-prefix=GANY %s
 // RUN: %clang -### -c -ggdb %s 2>&1 | FileCheck -check-prefix=GGDB %s
 // RUN: %clang -### -c -gfoo %s 2>&1 | FileCheck -check-prefix=GFOO %s
+// RUN: %clang -### -c -gline-tables-only %s 2>&1 \
+// RUN:             | FileCheck -check-prefix=GLTO %s
 //
 // G: "-cc1"
 // G: "-g"
@@ -25,3 +27,6 @@
 //
 // GFOO: "-cc1"
 // GFOO-NOT: "-g"
+//
+// GLTO: "-cc1"
+// GLTO: "-g"