From 82899d9d60710d42be45cfb7451d9dfbe07d88c3 Mon Sep 17 00:00:00 2001
From: Eric Christopher <echristo@gmail.com>
Date: Fri, 14 Mar 2014 20:53:49 +0000
Subject: [PATCH] If we see that we're emitting code for a function that
 doesn't have any lexical scopes then go ahead and turn on DW_AT_ranges for
 the compile unit since we would be claiming to describe in the CU a range for
 which we don't have information in the CU otherwise.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203969 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/AsmPrinter/DwarfDebug.cpp |  4 +-
 test/DebugInfo/cu-range-hole.ll       | 56 +++++++++++++++++++++++++++
 2 files changed, 59 insertions(+), 1 deletion(-)
 create mode 100644 test/DebugInfo/cu-range-hole.ll

diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index ed5bcf3c7bd..fa966d01c9d 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -1462,8 +1462,10 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
   // Grab the lexical scopes for the function, if we don't have any of those
   // then we're not going to be able to do anything.
   LScopes.initialize(*MF);
-  if (LScopes.empty())
+  if (LScopes.empty()) {
+    UsedNonDefaultText = true;
     return;
+  }
 
   assert(UserVariables.empty() && DbgValues.empty() && "Maps weren't cleaned");
 
diff --git a/test/DebugInfo/cu-range-hole.ll b/test/DebugInfo/cu-range-hole.ll
new file mode 100644
index 00000000000..46d2083cefa
--- /dev/null
+++ b/test/DebugInfo/cu-range-hole.ll
@@ -0,0 +1,56 @@
+; REQUIRES: object-emission
+; RUN: %llc_dwarf -O0 -filetype=obj %s -o %t
+; RUN: llvm-dwarfdump %t | FileCheck %s
+
+; Check that we emit ranges for this CU since we have a function with and
+; without debug info.
+; CHECK: DW_TAG_compile_unit
+; CHECK: DW_AT_ranges
+; CHECK: DW_TAG_subprogram
+
+; Function Attrs: nounwind uwtable
+define i32 @foo(i32 %a) #0 {
+entry:
+  %a.addr = alloca i32, align 4
+  store i32 %a, i32* %a.addr, align 4
+  call void @llvm.dbg.declare(metadata !{i32* %a.addr}, metadata !12), !dbg !13
+  %0 = load i32* %a.addr, align 4, !dbg !14
+  %add = add nsw i32 %0, 5, !dbg !14
+  ret i32 %add, !dbg !14
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata) #1
+
+; Function Attrs: nounwind uwtable
+define i32 @bar(i32 %b) #0 {
+entry:
+  %b.addr = alloca i32, align 4
+  store i32 %b, i32* %b.addr, align 4
+  %0 = load i32* %b.addr, align 4
+  %add = add nsw i32 %0, 1
+  ret i32 %add
+}
+
+attributes #0 = { nounwind uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { nounwind readnone }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!9, !10}
+!llvm.ident = !{!11, !11}
+
+!0 = metadata !{i32 786449, metadata !1, i32 12, metadata !"clang version 3.5.0 (trunk 203945) (llvm/trunk 203946)", i1 false, metadata !"", i32 0, metadata !2, metadata !2, metadata !3, metadata !2, metadata !2, metadata !"", i32 1}
+!1 = metadata !{metadata !"foo.c", metadata !"/usr/local/google/home/echristo"}
+!2 = metadata !{}
+!3 = metadata !{metadata !4}
+!4 = metadata !{i32 786478, metadata !1, metadata !5, metadata !"foo", metadata !"foo", metadata !"", i32 1, metadata !6, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, i32 (i32)* @foo, null, null, metadata !2, i32 1} ; [ DW_TAG_subprogram ] [line 1] [def] [foo]
+!5 = metadata !{i32 786473, metadata !1}          ; [ DW_TAG_file_type ] [/usr/local/google/home/echristo/foo.c]
+!6 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !7, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!7 = metadata !{metadata !8, metadata !8}
+!8 = metadata !{i32 786468, null, null, metadata !"int", i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0, enc DW_ATE_signed]
+!9 = metadata !{i32 2, metadata !"Dwarf Version", i32 4}
+!10 = metadata !{i32 1, metadata !"Debug Info Version", i32 1}
+!11 = metadata !{metadata !"clang version 3.5.0 (trunk 203945) (llvm/trunk 203946)"}
+!12 = metadata !{i32 786689, metadata !4, metadata !"a", metadata !5, i32 16777217, metadata !8, i32 0, i32 0} ; [ DW_TAG_arg_variable ] [a] [line 1]
+!13 = metadata !{i32 1, i32 0, metadata !4, null}
+!14 = metadata !{i32 2, i32 0, metadata !4, null}
-- 
2.34.1