[Debugify] Do not report line 0 locations as errors

The checking logic should not treat artificial locations as being
somehow problematic. Producing these locations can be the desired
behavior of some passes.

See llvm.org/PR37961.

llvm-svn: 335897

Author: vedantk

llvm/test/DebugInfo/debugify-report-missing-locs-only.ll

@@ -0,0 +1,31 @@
+; RUN: opt -check-debugify < %s -S -o - 2>&1 | FileCheck %s
+
+; CHECK: ERROR: Instruction with empty DebugLoc in function foo --   ret void
+define void @foo() !dbg !6 {
+  ret void
+}
+
+; CHECK-NOT: ERROR: Instruction with empty DebugLoc in function bar
+define i32 @bar() !dbg !9 {
+  ret i32 0, !dbg !15
+}
+
+declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.debugify = !{!3, !4}
+!llvm.module.flags = !{!5}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer: "debugify", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "void", directory: "/")
+!2 = !{}
+!3 = !{i32 6}
+!4 = !{i32 1}
+!5 = !{i32 2, !"Debug Info Version", i32 3}
+!6 = distinct !DISubprogram(name: "foo", linkageName: "foo", scope: null, file: !1, line: 1, type: !7, isLocal: false, isDefinition: true, scopeLine: 1, isOptimized: true, unit: !0, retainedNodes: !2)
+!7 = !DISubroutineType(types: !2)
+!9 = distinct !DISubprogram(name: "bar", linkageName: "bar", scope: null, file: !1, line: 2, type: !7, isLocal: false, isDefinition: true, scopeLine: 2, isOptimized: true, unit: !0, retainedNodes: !10)
+!10 = !{!11}
+!11 = !DILocalVariable(name: "1", scope: !9, file: !1, line: 3, type: !12)
+!12 = !DIBasicType(name: "ty32", size: 32, encoding: DW_ATE_unsigned)
+!15 = !DILocation(line: 0, column: 1, scope: !9)

llvm/tools/opt/Debugify.cpp

@@ -237,11 +237,13 @@ bool checkDebugifyMetadata(Module &M,
         continue;
       }
 
-      dbg() << "ERROR: Instruction with empty DebugLoc in function ";
-      dbg() << F.getName() << " --";
-      I.print(dbg());
-      dbg() << "\n";
-      HasErrors = true;
+      if (!DL) {
+        dbg() << "ERROR: Instruction with empty DebugLoc in function ";
+        dbg() << F.getName() << " --";
+        I.print(dbg());
+        dbg() << "\n";
+        HasErrors = true;
+      }
     }
 
     // Find missing variables and mis-sized debug values.