[SystemZ] Make sure that SystemZAddressingMode::dump() does not crash.

[jonpa]

Summary

I tried to compile a file with '-mllvm -debug', which caused a crash. This time this was during isel, where the common code did not properly handle a call to printIRSlotNumber without a Function pointer set. This occurred because SystemZAddressingMode::dump() was calling SDNode::dump() without passing the DAG pointer.

This patch:

1. It seems reasonable that the common code does not crash, and this patch at least prints a question mark instead of calling printIRSlotNumber() when the Function pointer is not set.
2. Since the DAG is available, SystemZAddressingMode::dump() should pass it.

My problem would disappear even without (1) since (2) avoids it. This also means there is no test case for (1). Adding reviewer for (1) also.

[uweigand]

The SystemZ parts LGTM.

[thegameg]

lib/CodeGen/MachineOperand.cpp

464

Can we make this:

int Slot = MST.getCurrentFunction() ? MST.getLocalSlot(&V) : -1;
MachineOperand::printIRSlotNumber(OS, Slot);

?

That way, printIRSlotNumber will print <badref> instead of ?.

[jonpa]

Thanks for review. SystemZ changes committed as r345347.

lib/CodeGen/MachineOperand.cpp

464

Yes, I checked that we get this output. Committed this separately as r345342

lib/CodeGen/MachineOperand.cpp

if (isa<Constant>(V)) {
     OS << '`';
     return;
   }
   OS << "%ir.";
   if (V.hasName()) {
     printLLVMNameWithoutPrefix(OS, V.getName());
     return;
   }
+  if (MST.getCurrentFunction())
     MachineOperand::printIRSlotNumber(OS, MST.getLocalSlot(&V));
+  else
+    OS << "?";
 }
 
 static void printSyncScope(raw_ostream &OS, const LLVMContext &Context,
                            SyncScope::ID SSID,
                            SmallVectorImpl<StringRef> &SSNs) {
   switch (SSID) {
   case SyncScope::System:
     break;

lib/Target/SystemZ/SystemZISelDAGToDAG.cpp

: Form(form), DR(dr), Base(), Disp(0), Index(),
       IncludesDynAlloc(false) {}
 
   // True if the address can have an index register.
   bool hasIndexField() { return Form != FormBD; }
 
   // True if the address can (and must) include ADJDYNALLOC.
   bool isDynAlloc() { return Form == FormBDXDynAlloc; }
 
-  void dump() {
+  void dump(const llvm::SelectionDAG *DAG) {
     errs() << "SystemZAddressingMode " << this << '\n';
 
     errs() << " Base ";
     if (Base.getNode())
-      Base.getNode()->dump();
+      Base.getNode()->dump(DAG);
     else
       errs() << "null\n";
 
     if (hasIndexField()) {
       errs() << " Index ";
       if (Index.getNode())
-        Index.getNode()->dump();
+        Index.getNode()->dump(DAG);
       else
         errs() << "null\n";
     }
 
     errs() << " Disp " << Disp;
     if (IncludesDynAlloc)
       errs() << " + ADJDYNALLOC";
     errs() << '\n';
bool SystemZDAGToDAGISel::selectAddress(SDValue Addr,
   // Reject cases where the other instruction in a pair should be used.
   if (!isValidDisp(AM.DR, AM.Disp))
     return false;
 
   // Make sure that ADJDYNALLOC is included where necessary.
   if (AM.isDynAlloc() && !AM.IncludesDynAlloc)
     return false;
 
-  LLVM_DEBUG(AM.dump());
+  LLVM_DEBUG(AM.dump(CurDAG));
   return true;
 }
 
 // Insert a node into the DAG at least before Pos.  This will reposition
 // the node as needed, and will assign it a node ID that is <= Pos's ID.
 // Note that this does *not* preserve the uniqueness of node IDs!
 // The selection DAG must no longer depend on their uniqueness when this
 // function is used.

test/CodeGen/SystemZ/isel-debug.ll

+; RUN: llc < %s -mtriple=s390x-linux-gnu -debug-only=systemz-isel -o - 2>&1 | \
+; RUN:   FileCheck %s
+
+; REQUIRES: asserts
+;
+; Check that some debug output is printed without problems.
+; CHECK: SystemZAddressingMode
+; CHECK: Base
+; CHECK: Index
+; CHECK: Disp
+
+define void @fun(i64* %ptr) {
+entry:
+  %0 = bitcast i64* %ptr to i32**
+  %1 = load i32*, i32** %0, align 8
+  %xpv_pv = getelementptr inbounds i32, i32* %1
+  store i32 0, i32* %xpv_pv
+  ret void
+}