[PATCH] D71480: [BasicBlockUtils] Fix dbg.value elimination problem in MergeBlockIntoPredecessor

[Bjorn Pettersson via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rGe5f07080b8ac: [BasicBlockUtils] Fix dbg.value elimination problem in MergeBlockIntoPredecessor (authored by bjope).

Changed prior to commit:
  https://reviews.llvm.org/D71480?vs=233963&id=234011#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D71480/new/

https://reviews.llvm.org/D71480

Files:
  llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
  llvm/test/DebugInfo/NVPTX/debug-loc-offset.ll
  llvm/test/Transforms/LoopRotate/dbg-value-duplicates-2.ll
  llvm/test/Transforms/SimplifyCFG/hoist-dbgvalue-inlined.ll


Index: llvm/test/Transforms/SimplifyCFG/hoist-dbgvalue-inlined.ll
===================================================================
--- llvm/test/Transforms/SimplifyCFG/hoist-dbgvalue-inlined.ll
+++ llvm/test/Transforms/SimplifyCFG/hoist-dbgvalue-inlined.ll
@@ -8,7 +8,6 @@
 
 ; CHECK:  %vala = load i64, i64* %ptr
 ; CHECK-NEXT:  call void @llvm.dbg.value(metadata i64 %vala, metadata [[MD:![0-9]*]]
-; CHECK-NEXT:  call void @llvm.dbg.value(metadata i64 %vala, metadata [[MD]]
 ; CHECK-NEXT:  %valbmasked = and i64 %vala, 1
 
 a:                                              ; preds = %init
Index: llvm/test/Transforms/LoopRotate/dbg-value-duplicates-2.ll
===================================================================
--- llvm/test/Transforms/LoopRotate/dbg-value-duplicates-2.ll
+++ llvm/test/Transforms/LoopRotate/dbg-value-duplicates-2.ll
@@ -11,12 +11,10 @@
 ; CHECK-NEXT:    call void @llvm.dbg.value(metadata i16 [[TMP1]], metadata !12, metadata !DIExpression()), !dbg !13
 ; CHECK-NEXT:    [[TMP4:%.*]] = call i16 @wibble(i16 [[TMP1]]), !dbg !14
 ; CHECK-NEXT:    [[TMP5]] = add nsw i16 [[TMP4]], [[TMP1]], !dbg !14
+; CHECK-NEXT:    call void @llvm.dbg.value(metadata i16 [[TMP5]], metadata !12, metadata !DIExpression()), !dbg !13
 ; CHECK-NEXT:    [[TMP6:%.*]] = call i16 @wibble(i16 [[TMP4]]), !dbg !14
 ; CHECK-NEXT:    [[TMP7:%.*]] = mul nsw i16 [[TMP6]], 3, !dbg !14
 ; CHECK-NEXT:    [[TMP8:%.*]] = call i16 @wibble(i16 [[TMP7]]), !dbg !14
-; BUG: This dbg.value is expected to be placed directly after the add above.
-;      Otherwise variable "x" (!12) won't be described as having the correct value at the call to wibble just after the add.
-; CHECK-NEXT:    call void @llvm.dbg.value(metadata i16 [[TMP5]], metadata !12, metadata !DIExpression()), !dbg !13
 ; CHECK-NEXT:    [[TMP2:%.*]] = icmp slt i16 [[TMP5]], 17, !dbg !14
 ; CHECK-NEXT:    br i1 [[TMP2]], label [[BB2]], label [[BB3:%.*]], !dbg !14
 ; CHECK:       bb3:
Index: llvm/test/DebugInfo/NVPTX/debug-loc-offset.ll
===================================================================
--- llvm/test/DebugInfo/NVPTX/debug-loc-offset.ll
+++ llvm/test/DebugInfo/NVPTX/debug-loc-offset.ll
@@ -43,8 +43,8 @@
 ; CHECK: .loc [[CU2:[0-9]+]] 6 0
 ; CHECK: Lfunc_begin1:
 ; CHECK: .loc [[CU2]] 6 0
-; CHECK: //DEBUG_VALUE: baz:z <- {{[0-9]+}}
-; CHECK: //DEBUG_VALUE: baz:z <- {{[0-9]+}}
+; CHECK-NOT: //DEBUG_VALUE: baz:z
+; CHECK: //DEBUG_VALUE: baz:z <- undef
 ; CHECK: .loc [[CU2]] 10 0
 ; CHECK: ret;
 ; CHECK: }
Index: llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
===================================================================
--- llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -284,20 +284,10 @@
   // Add unreachable to now empty BB.
   new UnreachableInst(BB->getContext(), BB);
 
-  // Eliminate duplicate dbg.values describing the entry PHI node post-splice.
-  for (auto Incoming : IncomingValues) {
-    if (isa<Instruction>(*Incoming)) {
-      SmallVector<DbgValueInst *, 2> DbgValues;
-      SmallDenseSet<std::pair<DILocalVariable *, DIExpression *>, 2>
-          DbgValueSet;
-      llvm::findDbgValues(DbgValues, Incoming);
-      for (auto &DVI : DbgValues) {
-        auto R = DbgValueSet.insert({DVI->getVariable(), DVI->getExpression()});
-        if (!R.second)
-          DVI->eraseFromParent();
-      }
-    }
-  }
+  // Eliminate duplicate/redundant dbg.values. This seems to be a good place to
+  // do that since we might end up with redundant dbg.values describing the
+  // entry PHI node post-splice.
+  RemoveRedundantDbgInstrs(PredBB);
 
   // Inherit predecessors name if it exists.
   if (!PredBB->hasName())


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