[DebugInfo] Update loop metadata in stripNonLineTableDebugInfo

llvm/lib/IR/DebugInfo.cpp

@@ -675,15 +675,10 @@ bool llvm::stripNonLineTableDebugInfo(Module &M) {
         if (I.getDebugLoc() != DebugLoc())
           I.setDebugLoc(remapDebugLoc(I.getDebugLoc()));
 
-        // Remap DILocations in untyped MDNodes (e.g., llvm.loop).
-        SmallVector<std::pair<unsigned, MDNode *>, 2> MDs;
-        I.getAllMetadata(MDs);
-        for (auto Attachment : MDs)
-          if (auto *T = dyn_cast_or_null<MDTuple>(Attachment.second))
-            for (unsigned N = 0; N < T->getNumOperands(); ++N)
-              if (auto *Loc = dyn_cast_or_null<DILocation>(T->getOperand(N)))
-                if (Loc != DebugLoc())
-                  T->replaceOperandWith(N, remapDebugLoc(Loc));
+        // Remap DILocations in llvm.loop attachments.
+        updateLoopMetadataDebugLocations(I, [&](const DILocation &Loc) {
+          return remapDebugLoc(&Loc).get();
+        });
       }
     }
   }

llvm/unittests/IR/DebugInfoTest.cpp

@@ -6,11 +6,25 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/IR/DebugInfo.h"
+#include "llvm/AsmParser/Parser.h"
 #include "llvm/IR/DebugInfoMetadata.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/Verifier.h"
+#include "llvm/Support/SourceMgr.h"
 #include "gtest/gtest.h"
 
 using namespace llvm;
 
+static std::unique_ptr<Module> parseIR(LLVMContext &C, const char *IR) {
+  SMDiagnostic Err;
+  std::unique_ptr<Module> Mod = parseAssemblyString(IR, Err, C);
+  if (!Mod)
+    Err.print("DebugInfoTest", errs());
+  return Mod;
+}
+
 namespace {
 
 TEST(DINodeTest, getFlag) {
@@ -79,4 +93,56 @@ TEST(DINodeTest, splitFlags) {
 #undef CHECK_SPLIT
 }
 
+TEST(StripTest, LoopMetadata) {
+  LLVMContext C;
+  std::unique_ptr<Module> M = parseIR(C, R"(
+    define void @f() !dbg !5 {
+      ret void, !dbg !10, !llvm.loop !11
+    }
+
+    !llvm.dbg.cu = !{!0}
+    !llvm.debugify = !{!3, !3}
+    !llvm.module.flags = !{!4}
+
+    !0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer: "debugify", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+    !1 = !DIFile(filename: "loop.ll", directory: "/")
+    !2 = !{}
+    !3 = !{i32 1}
+    !4 = !{i32 2, !"Debug Info Version", i32 3}
+    !5 = distinct !DISubprogram(name: "f", linkageName: "f", scope: null, file: !1, line: 1, type: !6, scopeLine: 1, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !7)
+    !6 = !DISubroutineType(types: !2)
+    !7 = !{!8}
+    !8 = !DILocalVariable(name: "1", scope: !5, file: !1, line: 1, type: !9)
+    !9 = !DIBasicType(name: "ty32", size: 32, encoding: DW_ATE_unsigned)
+    !10 = !DILocation(line: 1, column: 1, scope: !5)
+    !11 = distinct !{!11, !10, !10}
+)");
+
+  // Look up the debug info emission kind for the CU via the loop metadata
+  // attached to the terminator. If, when stripping non-line table debug info,
+  // we update the terminator's metadata correctly, we should be able to
+  // observe the change in emission kind for the CU.
+  auto getEmissionKind = [&]() {
+    Instruction &I = *M->getFunction("f")->getEntryBlock().getFirstNonPHI();
+    MDNode *LoopMD = I.getMetadata(LLVMContext::MD_loop);
+    return cast<DILocation>(LoopMD->getOperand(1))
+        ->getScope()
+        ->getSubprogram()
+        ->getUnit()
+        ->getEmissionKind();
+  };
+
+  EXPECT_EQ(getEmissionKind(), DICompileUnit::FullDebug);
+
+  bool Changed = stripNonLineTableDebugInfo(*M);
+  EXPECT_TRUE(Changed);
+
+  EXPECT_EQ(getEmissionKind(), DICompileUnit::LineTablesOnly);
+
+  bool BrokenDebugInfo = false;
+  bool HardError = verifyModule(*M, &errs(), &BrokenDebugInfo);
+  EXPECT_FALSE(HardError);
+  EXPECT_FALSE(BrokenDebugInfo);
+}
+
 } // end namespace