[DebugInfo] Handle followup loop metadata in updateLoopMetadataDebugLocations

llvm/lib/IR/DebugInfo.cpp

@@ -375,6 +375,38 @@ bool DebugInfoFinder::addScope(DIScope *Scope) {
   return true;
 }
 
+/// Recursively handle DILocations in followup metadata etc.
+///
+/// TODO: If for example a followup loop metadata would refence itself this
+/// function would go into infinite recursion. We do not expect such cycles in
+/// the loop metadata (except for the self-referencing first element
+/// "LoopID"). However, we could at least handle such situations more gracefully
+/// somehow (e.g. by keeping track of visited nodes and dropping metadata).
+static Metadata *updateLoopMetadataDebugLocationsRecursive(
+    Metadata *MetadataIn, function_ref<Metadata *(Metadata *)> Updater) {
+  const MDTuple *M = dyn_cast_or_null<MDTuple>(MetadataIn);
+  // The loop metadata options should start with a MDString.
+  if (!M || M->getNumOperands() < 1 || !isa<MDString>(M->getOperand(0)))
+    return MetadataIn;
+
+  bool Updated = false;
+  SmallVector<Metadata *, 4> MDs{M->getOperand(0)};
+  for (Metadata *MD : llvm::drop_begin(M->operands())) {
+    if (!MD) {
+      MDs.push_back(nullptr);
+      continue;
+    }
+    Metadata *NewMD =
+        Updater(updateLoopMetadataDebugLocationsRecursive(MD, Updater));
+    if (NewMD)
+      MDs.push_back(NewMD);
+    Updated |= NewMD != MD;
+  }
+
+  assert(!M->isDistinct() && "M should not be distinct.");
+  return Updated ? MDNode::get(M->getContext(), MDs) : MetadataIn;
+}
+
 static MDNode *updateLoopMetadataDebugLocationsImpl(
     MDNode *OrigLoopID, function_ref<Metadata *(Metadata *)> Updater) {
   assert(OrigLoopID && OrigLoopID->getNumOperands() > 0 &&
@@ -385,11 +417,11 @@ static MDNode *updateLoopMetadataDebugLocationsImpl(
   // Save space for the self-referential LoopID.
   SmallVector<Metadata *, 4> MDs = {nullptr};
 
-  for (unsigned i = 1; i < OrigLoopID->getNumOperands(); ++i) {
-    Metadata *MD = OrigLoopID->getOperand(i);
+  for (Metadata *MD : llvm::drop_begin(OrigLoopID->operands())) {
     if (!MD)
       MDs.push_back(nullptr);
-    else if (Metadata *NewMD = Updater(MD))
+    else if (Metadata *NewMD = Updater(
+                 updateLoopMetadataDebugLocationsRecursive(MD, Updater)))
       MDs.push_back(NewMD);
   }
 

llvm/test/Transforms/Inline/dilocation-loop-metadata-update.ll

@@ -0,0 +1,83 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt < %s -passes=inline -S | FileCheck %s
+
+; When inlining we need to update DILocation recursively for the followup
+; metadata when updating llvm.loop metadata.
+
+define void @a() !dbg !3 {
+; CHECK-LABEL: define void @a(
+; CHECK-SAME: ) !dbg [[DBG3:![0-9]+]] {
+; CHECK-NEXT:  [[ENTRY:.*:]]
+; CHECK-NEXT:    br label %[[FOR_BODY:.*]]
+; CHECK:       [[FOR_BODY]]:
+; CHECK-NEXT:    br label %[[FOR_BODY]], !llvm.loop [[LOOP6:![0-9]+]]
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+  br label %for.body, !llvm.loop !6
+}
+
+define void @f() !dbg !17 {
+; CHECK-LABEL: define void @f(
+; CHECK-SAME: ) !dbg [[DBG17:![0-9]+]] {
+; CHECK-NEXT:  [[ENTRY:.*:]]
+; CHECK-NEXT:    br label %[[A_EXIT:.*]]
+; CHECK:       [[A_EXIT]]:
+; CHECK-NEXT:    br label %[[A_EXIT]], !llvm.loop [[LOOP18:![0-9]+]]
+; CHECK:       [[A_EXIT1:.*:]]
+; CHECK-NEXT:    ret void
+;
+entry:
+  call void @a(), !dbg !18
+  ret void
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang", isOptimized: true, runtimeVersion: 0, emissionKind: NoDebug, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "foo.c", directory: "/")
+!2 = !{i32 2, !"Debug Info Version", i32 3}
+!3 = distinct !DISubprogram(name: "a", scope: !1, file: !1, line: 3, type: !4, scopeLine: 3, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0)
+!4 = !DISubroutineType(types: !5)
+!5 = !{}
+!6 = distinct !{!6, !7, !8, !9, !10, !11}
+!7 = !DILocation(line: 6, column: 3, scope: !3)
+!8 = !DILocation(line: 7, column: 22, scope: !3)
+!9 = !{!"llvm.loop.mustprogress"}
+!10 = !{!"llvm.loop.distribute.enable", i1 true}
+!11 = !{!"llvm.loop.distribute.followup_all", !7, !8, !9, !12, !13, !14}
+!12 = !{!"llvm.loop.vectorize.width", i32 8}
+!13 = !{!"llvm.loop.vectorize.enable", i1 true}
+!14 = !{!"llvm.loop.vectorize.followup_all", !7, !8, !9, !15, !16}
+!15 = !{!"llvm.loop.isvectorized"}
+!16 = !{!"llvm.loop.unroll.count", i32 1}
+!17 = distinct !DISubprogram(name: "f", scope: !1, file: !1, line: 9, type: !4, scopeLine: 9, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0)
+!18 = !DILocation(line: 9, column: 12, scope: !17)
+;.
+; CHECK: [[META0:![0-9]+]] = distinct !DICompileUnit(language: DW_LANG_C11, file: [[META1:![0-9]+]], producer: "clang", isOptimized: true, runtimeVersion: 0, emissionKind: NoDebug, splitDebugInlining: false, nameTableKind: None)
+; CHECK: [[META1]] = !DIFile(filename: "{{.*}}foo.c", directory: {{.*}})
+; CHECK: [[DBG3]] = distinct !DISubprogram(name: "a", scope: [[META1]], file: [[META1]], line: 3, type: [[META4:![0-9]+]], scopeLine: 3, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: [[META0]])
+; CHECK: [[META4]] = !DISubroutineType(types: [[META5:![0-9]+]])
+; CHECK: [[META5]] = !{}
+; CHECK: [[LOOP6]] = distinct !{[[LOOP6]], [[META7:![0-9]+]], [[META8:![0-9]+]], [[META9:![0-9]+]], [[META10:![0-9]+]], [[META11:![0-9]+]]}
+; CHECK: [[META7]] = !DILocation(line: 6, column: 3, scope: [[DBG3]])
+; CHECK: [[META8]] = !DILocation(line: 7, column: 22, scope: [[DBG3]])
+; CHECK: [[META9]] = !{!"llvm.loop.mustprogress"}
+; CHECK: [[META10]] = !{!"llvm.loop.distribute.enable", i1 true}
+; CHECK: [[META11]] = !{!"llvm.loop.distribute.followup_all", [[META7]], [[META8]], [[META9]], [[META12:![0-9]+]], [[META13:![0-9]+]], [[META14:![0-9]+]]}
+; CHECK: [[META12]] = !{!"llvm.loop.vectorize.width", i32 8}
+; CHECK: [[META13]] = !{!"llvm.loop.vectorize.enable", i1 true}
+; CHECK: [[META14]] = !{!"llvm.loop.vectorize.followup_all", [[META7]], [[META8]], [[META9]], [[META15:![0-9]+]], [[META16:![0-9]+]]}
+; CHECK: [[META15]] = !{!"llvm.loop.isvectorized"}
+; CHECK: [[META16]] = !{!"llvm.loop.unroll.count", i32 1}
+; CHECK: [[DBG17]] = distinct !DISubprogram(name: "f", scope: [[META1]], file: [[META1]], line: 9, type: [[META4]], scopeLine: 9, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: [[META0]])
+; CHECK: [[LOOP18]] = distinct !{[[LOOP18]], [[META19:![0-9]+]], [[META21:![0-9]+]], [[META9]], [[META10]], [[META22:![0-9]+]]}
+; CHECK: [[META19]] = !DILocation(line: 6, column: 3, scope: [[DBG3]], inlinedAt: [[META20:![0-9]+]])
+; CHECK: [[META20]] = distinct !DILocation(line: 9, column: 12, scope: [[DBG17]])
+; CHECK: [[META21]] = !DILocation(line: 7, column: 22, scope: [[DBG3]], inlinedAt: [[META20]])
+; CHECK: [[META22]] = !{!"llvm.loop.distribute.followup_all", [[META19]], [[META21]], [[META9]], [[META12]], [[META13]], [[META23:![0-9]+]]}
+; CHECK: [[META23]] = !{!"llvm.loop.vectorize.followup_all", [[META19]], [[META21]], [[META9]], [[META15]], [[META16]]}
+;.