[SelectionDAG] Updates for -dag-dump-verbose

[bjope]

Summary

This patch makes some changes related to -dag-dump-verbose.
Main use case has been when debugging how SelectionDAG is
dealing with debug info (SDDbgValue nodes).

1. We now print the number of DbgValues that are mapped to each SDNode.
2. Removed duplicated printing of DebugLoc (nowadays DebugLoc is printed also when not using -dag-dump-verbose).
3. Renamed SDDbgValue::dump to SDDbgValue::print, and added a new SDDbgValue::dump that will start a new line after calling print.
4. SDDbgValue::print now prints "Order", and it also prints some additional information when kind is CONST/FRAMEIX/VREG.
5. SelectionDAG::dump() now dumps all SDDbgValue nodes after the list of SDNodes (both "regular" and "ByVal" SDDbgValue:s). Invalidated nodes are not printed.
6. Prohibit inline printing of SDNode operands that has SDDbgValue nodes associated to them.

[bjope]

@jmorse : Since you are working a little bit with the SelectionDAGBuilder and debug values etc, maybe you will find this patch helpful. It gives some more printouts for the "missing" DBG_VALUE nodes that normally isn't shown during ISel simply by using -debug or -dag-dump-verbose.

Before submitting this we need to decide upon a few things, such as:

1. should this be a separate option or could it simply be part of -dag-dump-verbose
2. should we convert -dag-dump-verbose into some multi-choice param with different verbosity levels

Maybe (1) is an acceptable solution.

Not sure about what kind of test cases that are needed for these. I haven't seen any test cases for -dag-dump-verbose so maybe it isn't that important to have tests for this kind of debugging aid?

[jmorse]

Hi Bjorn, this is highly useful and relevant to my interests,

In D56793#1360037, @bjope wrote:

Before submitting this we need to decide upon a few things, such as:

1. should this be a separate option or could it simply be part of -dag-dump-verbose
2. should we convert -dag-dump-verbose into some multi-choice param with different verbosity levels

IMHO this can be rolled into -dag-dump-verbose: for the normal use cases the user won't have any dbg.values, or should be able to trivially drop them if they don't want this information cluttering output.

Not sure about what kind of test cases that are needed for these. I haven't seen any test cases for -dag-dump-verbose so maybe it isn't that important to have tests for this kind of debugging aid?

I suspect no test is required (although I doubt it's written down anywhere). It'd be awkward to break someones CI testing because a non-functional textual representation changed. I've also seen a couple of reviews disallowing the use of -debug output to test the compiler behaviour.

include/llvm/CodeGen/SelectionDAG.h

1355–1357

Doesn't compile for me, the other GetDbgValues method is already const, so this only overloads the return type which C++ disallows.

1364–1367

Is it worth just removing the non-const DbgBegin/End here, as we return the same iterators anyway?

[bjope]

include/llvm/CodeGen/SelectionDAG.h

1355–1357

Ok. Sorry. I resurrected this from some old branch and forgot to verify that it works on latest trunk.
But since it seems useful I'll cleanup this a little bit (and of course making sure it compiles again).

[bjope]

Now refactored based on trunk (the first version I uploaded was a
quite old patch that didn't even compile, sorry for that).

I also removed the part about letting SelectionDAG::dump() dump
all SDNodes (even the single-use nodes normally printed inline)
on separate lines. I've always found it a little bit confusing
that it says "SelectionDAG has 22 nodes:" and then it prints
what seems to be less than 22 nodes, due to some being printed
inline (and the node id is not printed for the inlined ones).
I'm thinking about adding a new option for disabling the
inline printing, but that will go in a separate patch (it is
not really related to -dag-dump-verbose).

[bjope]

Some more updates (some tweaks after having looked at some logs).

include/llvm/CodeGen/SelectionDAG.h

#endif
 
   /// Add a dbg_label SDNode.
   void AddDbgLabel(SDDbgLabel *DB);
 
   /// Get the debug values which reference the given SDNode.
   ArrayRef<SDDbgValue*> GetDbgValues(const SDNode* SD) const {
     return DbgInfo->getSDDbgValues(SD);
   }
+  const ArrayRef<SDDbgValue*> GetDbgValues(const SDNode* SD) const {
+    return DbgInfo->getSDDbgValues(SD);
+  }
 
 public:
   /// Return true if there are any SDDbgValue nodes associated
   /// with this SelectionDAG.
   bool hasDebugValues() const { return !DbgInfo->empty(); }
 
   SDDbgInfo::DbgIterator DbgBegin() { return DbgInfo->DbgBegin(); }
   SDDbgInfo::DbgIterator DbgEnd()   { return DbgInfo->DbgEnd(); }
+  SDDbgInfo::DbgIterator DbgBegin() const { return DbgInfo->DbgBegin(); }
+  SDDbgInfo::DbgIterator DbgEnd() const  { return DbgInfo->DbgEnd(); }
 
   SDDbgInfo::DbgIterator ByvalParmDbgBegin() {
     return DbgInfo->ByvalParmDbgBegin();
   }
-
-  SDDbgInfo::DbgIterator ByvalParmDbgEnd()   {
+  SDDbgInfo::DbgIterator ByvalParmDbgEnd() {
     return DbgInfo->ByvalParmDbgEnd();
   }
 
+  SDDbgInfo::DbgIterator ByvalParmDbgBegin() const {
+    return DbgInfo->ByvalParmDbgBegin();
+  }
+  SDDbgInfo::DbgIterator ByvalParmDbgEnd() const {
+    return DbgInfo->ByvalParmDbgEnd();
+  }
+
   SDDbgInfo::DbgLabelIterator DbgLabelBegin() {
     return DbgInfo->DbgLabelBegin();
   }
   SDDbgInfo::DbgLabelIterator DbgLabelEnd() {
     return DbgInfo->DbgLabelEnd();
   }
 
   /// To be invoked on an SDNode that is slated to be erased. This

lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp

 //===- SelectionDAGDumper.cpp - Implement SelectionDAG::dump() ------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This implements the SelectionDAG::dump method and friends.
 //
 //===----------------------------------------------------------------------===//
 
+#include "SDNodeDbgValue.h"
 #include "llvm/ADT/APFloat.h"
 #include "llvm/ADT/APInt.h"
 #include "llvm/ADT/None.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/CodeGen/ISDOpcodes.h"
 #include "llvm/CodeGen/MachineBasicBlock.h"
 #include "llvm/CodeGen/MachineConstantPool.h"

 #include <iterator>
 
 using namespace llvm;
 
 static cl::opt<bool>
 VerboseDAGDumping("dag-dump-verbose", cl::Hidden,
                   cl::desc("Display more information when dumping selection "
                            "DAG nodes."));
+static cl::opt<bool>
+VerboseDbgDAGDumping("dag-dump-verbose-dbg", cl::Hidden,
+                     cl::desc("Display more information when dumping selection "
+                              "DAG nodes."));
 
 std::string SDNode::getOperationName(const SelectionDAG *G) const {
   switch (getOpcode()) {
   default:
     if (getOpcode() < ISD::BUILTIN_OP_END)
       return "<<Unknown DAG Node>>";
     if (isMachineOpcode()) {
       if (G)
if (unsigned int TF = BA->getTargetFlags())
                dyn_cast<AddrSpaceCastSDNode>(this)) {
     OS << '['
        << ASC->getSrcAddressSpace()
        << " -> "
        << ASC->getDestAddressSpace()
        << ']';
   }
 
-  if (VerboseDAGDumping) {
+  if (VerboseDbgDAGDumping) {
+    if (G && getHasDebugValue()) {
+      if (!G->GetDbgValues(this).empty())
+        OS << " [NoOfDbgValues=" << G->GetDbgValues(this).size() << ']';
+    } else if (getHasDebugValue())
+      OS << " [NoOfDbgValues>0]";
+  }
+
+  if (VerboseDAGDumping || VerboseDbgDAGDumping) {
     if (unsigned Order = getIROrder())
         OS << " [ORD=" << Order << ']';
 
     if (getNodeId() != -1)
       OS << " [ID=" << getNodeId() << ']';
     if (!(isa<ConstantSDNode>(this) || (isa<ConstantFPSDNode>(this))))
       OS << "# D:" << isDivergent();
 

  if (Expr->getNumElements())
    Expr->dump();
 #endif
 }
 
 /// Return true if this node is so simple that we should just print it inline
 /// if it appears as an operand.
 static bool shouldPrintInline(const SDNode &Node) {
+  if (VerboseDAGDumping || VerboseDbgDAGDumping)
+    return false;
   if (Node.getOpcode() == ISD::EntryToken)
     return false;
   return Node.getNumOperands() == 0;
 }
 
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
 static void DumpNodes(const SDNode *N, unsigned indent, const SelectionDAG *G) {
   for (const SDValue &Op : N->op_values()) {
for (allnodes_const_iterator I = allnodes_begin(), E = allnodes_end();
     const SDNode *N = &*I;
     if (!N->hasOneUse() && N != getRoot().getNode() &&
         (!shouldPrintInline(*N) || N->use_empty()))
       DumpNodes(N, 2, this);
   }
 
   if (getRoot().getNode()) DumpNodes(getRoot().getNode(), 2, this);
   dbgs() << "\n\n";
+
+  SDDbgInfo::DbgIterator DI = DbgBegin();
+  SDDbgInfo::DbgIterator DE = DbgEnd();
+  for (; DI != DE; ++DI) {
+    dbgs() << "SDDbgValue:"
+           << " Kind=" << (*DI)->getKind()
+           << " Order=" << (*DI)->getOrder()
+           << " Var=" << (*DI)->getVariable()->getName()
+           << "\n\n";
+  }
+  DI = ByvalParmDbgBegin();
+  DE = ByvalParmDbgEnd();
+  for (; DI != DE; ++DI) {
+    dbgs() << "Byval SDDbgValue:"
+           << " Kind=" << (*DI)->getKind()
+           << " Order=" << (*DI)->getOrder()
+           << " Var=" << (*DI)->getVariable()->getName()
+           << "\n\n";
+  }
 }
 #endif
 
 void SDNode::printr(raw_ostream &OS, const SelectionDAG *G) const {
   OS << PrintNodeId(*this) << ": ";
   print_types(OS, G);
   OS << " = " << getOperationName(G);
   print_details(OS, G);