Reapply r160148 (reverted in r163570) fixing spurious breakpoints in modern GDB

This reapplies the fix for PR13303 now with more justification. Based on my
execution of the GDB 7.5 test suite this results in:

expected passes: 16101 -> 20890 (+30%)
unexpected failures: 4826 -> 637 (-77%)

There are 23 checks that used to pass and now fail. They are all in
gdb.reverse. Investigating a few looks like they were accidentally passing
due to extra breakpoints being set by this bug. They're generally due to the
difference in end location between gcc and clang, the test suite is trying to
set breakpoints on the closing '}' that clang doesn't associate with any
instructions.

llvm-svn: 169304

2 files changed, 29 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index d008f0b296c..32765758429 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -1511,7 +1511,7 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
                                        MF->getFunction()->getContext());
     recordSourceLine(FnStartDL.getLine(), FnStartDL.getCol(),
                      FnStartDL.getScope(MF->getFunction()->getContext()),
-                     0);
+                     DWARF2_FLAG_IS_STMT);
   }
 }
 
diff --git a/llvm/test/DebugInfo/X86/pr13303.ll b/llvm/test/DebugInfo/X86/pr13303.ll
new file mode 100644
index 00000000000..e820cb564cf
--- /dev/null
+++ b/llvm/test/DebugInfo/X86/pr13303.ll
@@ -0,0 +1,28 @@
+; RUN: llc %s -o %t -filetype=obj -mtriple=x86_64-unknown-linux-gnu
+; RUN: llvm-dwarfdump %t | FileCheck %s
+; PR13303
+
+; Check that the prologue ends with is_stmt here.
+; CHECK: 0x0000000000000000 {{.*}} is_stmt
+
+define i32 @main() nounwind uwtable {
+entry:
+  %retval = alloca i32, align 4
+  store i32 0, i32* %retval
+  ret i32 0, !dbg !10
+}
+
+!llvm.dbg.cu = !{!0}
+
+!0 = metadata !{i32 786449, i32 0, i32 12, metadata !"PR13303.c", metadata !"/home/probinson", metadata !"clang version 3.2 (trunk 160143)", i1 true, i1 false, metadata !"", i32 0, metadata !1, metadata !1, metadata !3, metadata !1} ; [ DW_TAG_compile_unit ] [/home/probinson/PR13303.c] [DW_LANG_C99]
+!1 = metadata !{metadata !2}
+!2 = metadata !{i32 0}
+!3 = metadata !{metadata !4}
+!4 = metadata !{metadata !5}
+!5 = metadata !{i32 786478, i32 0, metadata !6, metadata !"main", metadata !"main", metadata !"", metadata !6, i32 1, metadata !7, i1 false, i1 true, i32 0, i32 0, null, i32 0, i1 false, i32 ()* @main, null, null, metadata !1, i32 1} ; [ DW_TAG_subprogram ] [line 1] [def] [main]
+!6 = metadata !{i32 786473, metadata !"PR13303.c", metadata !"/home/probinson", null} ; [ DW_TAG_file_type ]
+!7 = metadata !{i32 786453, i32 0, metadata !"", i32 0, i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !8, i32 0, i32 0} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!8 = metadata !{metadata !9}
+!9 = metadata !{i32 786468, null, metadata !"int", null, 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]
+!10 = metadata !{i32 1, i32 14, metadata !11, null}
+!11 = metadata !{i32 786443, metadata !5, i32 1, i32 12, metadata !6, i32 0} ; [ DW_TAG_lexical_block ] [/home/probinson/PR13303.c]