[PATCH] D44546: [SelectionDAG] Transfer DbgValues when integer operations are promoted

[Vedant Kumar via Phabricator via llvm-commits]

vsk added a comment.

In https://reviews.llvm.org/D44546#1039654, @asmith wrote:

> This is to fix DebugInfo/Generic/linear-dbg-value.ll and won't repro on an in-tree target.
>
> Is there a way to write a test that will force selection dag to promote an integer?


We can probably find a test by adding an assertion that catches interesting input, and throwing lots of debug info at the backend. E.g:

  diff --git a/include/llvm/CodeGen/SelectionDAG.h b/include/llvm/CodeGen/SelectionDAG.h
  index 0df75cb0b1d..5c2fc3bee5e 100644
  --- a/include/llvm/CodeGen/SelectionDAG.h
  +++ b/include/llvm/CodeGen/SelectionDAG.h
  @@ -1228,7 +1228,7 @@ public:
     /// Transfer debug values from one node to another, while optionally
     /// generating fragment expressions for split-up values. If \p InvalidateDbg
     /// is set, debug values are invalidated after they are transferred.
  -  void transferDbgValues(SDValue From, SDValue To, unsigned OffsetInBits = 0,
  +  bool transferDbgValues(SDValue From, SDValue To, unsigned OffsetInBits = 0,
                            unsigned SizeInBits = 0, bool InvalidateDbg = true);
   
     /// Remove the specified node from the system. If any of its
  diff --git a/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp b/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp
  index 4438ee7878b..03eab5cd94e 100644
  --- a/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp
  +++ b/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp
  @@ -776,6 +776,9 @@ void DAGTypeLegalizer::SetPromotedInteger(SDValue Op, SDValue Result) {
     SDValue &OpEntry = PromotedIntegers[Op];
     assert(!OpEntry.getNode() && "Node is already promoted!");
     OpEntry = Result;
  +
  +  bool FoundIt = DAG.transferDbgValues(Op, Result);
  +  assert(!FoundIt && "Found a test case");
   }
   
   void DAGTypeLegalizer::SetSoftenedFloat(SDValue Op, SDValue Result) {
  diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
  index aac79075e6e..ea6e151dad2 100644
  --- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
  +++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
  @@ -7187,7 +7187,7 @@ SDDbgValue *SelectionDAG::getFrameIndexDbgValue(DIVariable *Var,
     return new (DbgInfo->getAlloc()) SDDbgValue(Var, Expr, FI, DL, O);
   }
   
  -void SelectionDAG::transferDbgValues(SDValue From, SDValue To,
  +bool SelectionDAG::transferDbgValues(SDValue From, SDValue To,
                                        unsigned OffsetInBits, unsigned SizeInBits,
                                        bool InvalidateDbg) {
     SDNode *FromNode = From.getNode();
  @@ -7198,10 +7198,10 @@ void SelectionDAG::transferDbgValues(SDValue From, SDValue To,
     // TODO: assert(From != To && "Redundant dbg value transfer");
     // TODO: assert(FromNode != ToNode && "Intranode dbg value transfer");
     if (From == To || FromNode == ToNode)
  -    return;
  +    return false;
   
     if (!FromNode->getHasDebugValue())
  -    return;
  +    return false;
   
     SmallVector<SDDbgValue *, 2> ClonedDVs;
     for (SDDbgValue *Dbg : GetDbgValues(FromNode)) {
  @@ -7242,6 +7242,7 @@ void SelectionDAG::transferDbgValues(SDValue From, SDValue To,
   
     for (SDDbgValue *Dbg : ClonedDVs)
       AddDbgValue(Dbg, ToNode, false);
  +  return ClonedDVs.size();
   }
   
   void SelectionDAG::salvageDebugInfo(SDNode &N) {

Here's a test that trips the assert:

$ ./bin/llvm-lit /Users/vsk/src/llvm.org-debugify/llvm/test/CodeGen/ARM/debug-info-d16-reg.ll -a
Assertion failed: (!FoundIt && "Found a test case"), function SetPromotedInteger

You could probably modify this for your purposes.


Repository:
  rL LLVM

https://reviews.llvm.org/D44546