Emit 'no line' information for interesting 'orphan' instructions.

DWARF specifies that "line 0" really means "no appropriate source
location" in the line table.  Use this for branch targets and some
other cases that have no specified source location, to prevent
inheriting unfortunate line numbers from physically preceding
instructions (which might be from completely unrelated source).

Differential Revision: http://reviews.llvm.org/D24180

llvm-svn: 288212

1 files changed, 74 insertions, 0 deletions

diff --git a/llvm/test/DebugInfo/X86/dwarf-no-source-loc.ll b/llvm/test/DebugInfo/X86/dwarf-no-source-loc.ll
new file mode 100644
index 00000000000..d71f95d999e
--- /dev/null
+++ b/llvm/test/DebugInfo/X86/dwarf-no-source-loc.ll
@@ -0,0 +1,74 @@
+; Verify "no source location" directives appear in appropriate places.
+; RUN: llc %s -o - | FileCheck %s
+
+; Generated from this .cpp targeting linux using -g
+; and then removed function attributes as clutter.
+;
+; void bar(int *);
+; void baz(int *);
+; # 5 "no-source-loc.cpp"
+; void foo(int x) {
+;   int z;
+;   if (x)
+; # 20 "include.h"
+;     bar(&z);
+; # 10 "no-source-loc.cpp"
+;   baz(&z);
+; }
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: uwtable
+define void @_Z3fooi(i32 %x) !dbg !6 {
+entry:
+  %x.addr = alloca i32, align 4
+  %z = alloca i32, align 4
+  store i32 %x, i32* %x.addr, align 4
+  %0 = load i32, i32* %x.addr, align 4, !dbg !8
+  %tobool = icmp ne i32 %0, 0, !dbg !8
+  br i1 %tobool, label %if.then, label %if.end, !dbg !8
+
+if.then:                                          ; preds = %entry
+  call void @_Z3barPi(i32* %z), !dbg !9
+  br label %if.end, !dbg !9
+
+if.end:                                           ; preds = %if.then, %entry
+  call void @_Z3bazPi(i32* %z), !dbg !12
+  ret void, !dbg !14
+}
+
+; CHECK:      .loc 1 7 7
+; CHECK-NOT:  .loc
+; CHECK:      .loc 1 0 0 is_stmt 0
+; CHECK-NOT:  .loc
+; CHECK:      .loc 2 20 5 is_stmt 1
+; CHECK:      .LBB0_2:
+; CHECK-NEXT: .loc 2 0 0 is_stmt 0
+; CHECK-NOT:  .loc
+; CHECK:      .loc 1 10 3 is_stmt 1
+
+
+declare void @_Z3barPi(i32*)
+
+declare void @_Z3bazPi(i32*)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+!llvm.ident = !{!5}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 4.0.0 (trunk 278782)", isOptimized: false, runtimeVersion: 0, emissionKind: LineTablesOnly, enums: !2)
+!1 = !DIFile(filename: "no-source-loc.cpp", directory: "/tests")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{!"clang version 4.0.0 (trunk 278782)"}
+!6 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 5, type: !7, isLocal: false, isDefinition: true, scopeLine: 5, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)
+!7 = !DISubroutineType(types: !2)
+!8 = !DILocation(line: 7, column: 7, scope: !6)
+!9 = !DILocation(line: 20, column: 5, scope: !10)
+!10 = !DILexicalBlockFile(scope: !6, file: !11, discriminator: 0)
+!11 = !DIFile(filename: "include.h", directory: "/tests")
+!12 = !DILocation(line: 10, column: 3, scope: !13)
+!13 = !DILexicalBlockFile(scope: !6, file: !1, discriminator: 0)
+!14 = !DILocation(line: 11, column: 1, scope: !13)