Add a debug dump for DbgValueHistoryMap

[vsk]

Summary

This makes it easier to inspect the results of
DbgValueHistoryCalculator.

[aprantl]

lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.h

56

I vaguely recall that there is an LLVM_DUMP_FUNCTION macro for this purpose?

lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.h

public:
   // Returns register currently describing @Var. If @Var is currently
   // unaccessible or is not described by a register, returns 0.
   unsigned getRegisterForVar(InlinedVariable Var) const;
 
   bool empty() const { return VarInstrRanges.empty(); }
   void clear() { VarInstrRanges.clear(); }
   InstrRangesMap::const_iterator begin() const { return VarInstrRanges.begin(); }
   InstrRangesMap::const_iterator end() const { return VarInstrRanges.end(); }
+
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+  void dump() const;
+#endif
 };
 
 void calculateDbgValueHistory(const MachineFunction *MF,
                               const TargetRegisterInfo *TRI,
                               DbgValueHistoryMap &Result);
 
 } // end namespace llvm
 
 #endif // LLVM_LIB_CODEGEN_ASMPRINTER_DBGVALUEHISTORYCALCULATOR_H

lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp

if (!MBB.empty() && &MBB != &MF->back()) {
         auto CurElem = I++; // CurElem can be erased below.
         if (TRI->isVirtualRegister(CurElem->first) ||
             ChangingRegs.test(CurElem->first))
           clobberRegisterUses(RegVars, CurElem, Result, MBB.back());
       }
     }
   }
 }
+
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+void DbgValueHistoryMap::dump() const {
+  dbgs() << "DbgValueHistoryMap:\n";
+  for (const auto &VarRangePair : *this) {
+    const InlinedVariable &Var = VarRangePair.first;
+    const InstrRanges &Ranges = VarRangePair.second;
+
+    const DILocalVariable *LocalVar = Var.first;
+    const DILocation *Location = Var.second;
+
+    dbgs() << " - " << LocalVar->getName() << " at ";
+
+    if (Location)
+      dbgs() << Location->getFilename() << ":" << Location->getLine() << ":"
+             << Location->getColumn();
+    else
+      dbgs() << "<unknown location>";
+
+    dbgs() << " --\n";
+
+    for (const InstrRange &Range : Ranges) {
+      dbgs() << "   Begin: " << *Range.first;
+      if (Range.second)
+        dbgs() << "   End  : " << *Range.second;
+      dbgs() << "\n";
+    }
+  }
+}
+#endif

lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp

 #include "llvm/CodeGen/MachineInstr.h"
 #include "llvm/CodeGen/MachineModuleInfo.h"
 #include "llvm/CodeGen/TargetSubtargetInfo.h"
 #include "llvm/IR/DebugInfo.h"
 #include "llvm/MC/MCStreamer.h"
 
 using namespace llvm;
 
+#define DEBUG_TYPE "dwarfdebug"
+
 Optional<DbgVariableLocation>
 DbgVariableLocation::extractFromMachineInstruction(
     const MachineInstr &Instruction) {
   DbgVariableLocation Location;
   if (!Instruction.isDebugValue())
     return None;
   if (!Instruction.getOperand(0).isReg())
     return None;
void DebugHandlerBase::beginFunction(const MachineFunction *MF) {
 
   // Make sure that each lexical scope will have a begin/end label.
   identifyScopeMarkers();
 
   // Calculate history for local variables.
   assert(DbgValues.empty() && "DbgValues map wasn't cleaned!");
   calculateDbgValueHistory(MF, Asm->MF->getSubtarget().getRegisterInfo(),
                            DbgValues);
+  LLVM_DEBUG(DbgValues.dump());
 
   // Request labels for the full history.
   for (const auto &I : DbgValues) {
     const auto &Ranges = I.second;
     if (Ranges.empty())
       continue;
 
     // The first mention of a function argument gets the CurrentFnBegin

test/DebugInfo/X86/dump-dbg-value-hist-calc.ll

+; REQUIRES: asserts
+; RUN: opt -S -o - -debugify %s \
+; RUN:   | %llc_dwarf -debug-only=dwarfdebug -o /dev/null 2>&1 \
+; RUN:   | FileCheck %s
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx"
+
+; CHECK: DbgValueHistoryMap:
+; CHECK-NEXT:  - 1 at <unknown location> --
+; CHECK-NEXT:    Begin: DBG_VALUE {{.*}} line no:1
+; CHECK-NEXT:    End  : CALL64pcrel32 @h{{.*}}:2:1
+
+define void @f() {
+entry:
+  %a = add i32 0, 0
+  %b = call i32 @h(i32 %a)
+  ret void
+}
+
+declare i32 @h(i32)