Simplified it a bit.

sc/inc/dpitemdata.hxx

@@ -72,7 +72,7 @@ public:
     ScDPItemData(sal_uLong nNF, const rtl::OUString & rS, double fV, sal_uInt8 bF);
     ScDPItemData(const rtl::OUString& rS, double fV = 0.0, bool bHV = false,
                  const sal_uLong nNumFormat = 0, bool bData = true);
-    ScDPItemData(ScDocument* pDoc, SCCOL nCol, SCROW nRow, SCTAB nDocTab, bool bLabel);
+    ScDPItemData(ScDocument* pDoc, SCCOL nCol, SCROW nRow, SCTAB nDocTab);
 
     void SetString(const rtl::OUString& rS);
     bool IsCaseInsEqual(const ScDPItemData& r) const;

sc/source/core/data/dpitemdata.cxx

@@ -51,7 +51,7 @@ ScDPItemData::ScDPItemData(const rtl::OUString& rS, double fV, bool bHV, const s
 {
 }
 
-ScDPItemData::ScDPItemData(ScDocument* pDoc, SCCOL nCol, SCROW nRow, SCTAB nDocTab, bool bLabel) :
+ScDPItemData::ScDPItemData(ScDocument* pDoc, SCCOL nCol, SCROW nRow, SCTAB nDocTab) :
     mnNumFormat( 0 ), mfValue(0.0), mbFlag( 0 )
 {
     rtl::OUString aDocStr = pDoc->GetString(nCol, nRow, nDocTab);
@@ -78,22 +78,8 @@ ScDPItemData::ScDPItemData(ScDocument* pDoc, SCCOL nCol, SCROW nRow, SCTAB nDocT
         mnNumFormat = pDoc->GetNumberFormat( ScAddress( nCol, nRow, nDocTab ) );
         isDate( nFormat ) ? ( mbFlag |= MK_DATE ) : (mbFlag &= ~MK_DATE);
     }
-    else if (bLabel || pDoc->HasData(nCol, nRow, nDocTab))
+    else if (pDoc->HasData(nCol, nRow, nDocTab))
     {
-        if (bLabel && aDocStr.isEmpty())
-        {
-            // Replace an empty label string with column name.
-            rtl::OUStringBuffer aBuf;
-            aBuf.append(ScGlobal::GetRscString(STR_COLUMN));
-            aBuf.append(sal_Unicode(' '));
-
-            ScAddress aColAddr(nCol, 0, 0);
-            rtl::OUString aColStr;
-            aColAddr.Format(aColStr, SCA_VALID_COL, NULL);
-            aBuf.append(aColStr);
-            aDocStr = aBuf.makeStringAndClear();
-        }
-
         SetString(aDocStr);
     }
 }

sc/source/core/data/dptablecache.cxx

@@ -276,6 +276,25 @@ private:
     ScDocument* mpDoc;
 };
 
+rtl::OUString createLabelString(ScDocument* pDoc, SCCOL nCol, SCROW nRow, SCTAB nTab)
+{
+    rtl::OUString aDocStr = pDoc->GetString(nCol, nRow, nTab);
+    if (aDocStr.isEmpty())
+    {
+        // Replace an empty label string with column name.
+        rtl::OUStringBuffer aBuf;
+        aBuf.append(ScGlobal::GetRscString(STR_COLUMN));
+        aBuf.append(sal_Unicode(' '));
+
+        ScAddress aColAddr(nCol, 0, 0);
+        rtl::OUString aColStr;
+        aColAddr.Format(aColStr, SCA_VALID_COL, NULL);
+        aBuf.append(aColStr);
+        aDocStr = aBuf.makeStringAndClear();
+    }
+    return aDocStr;
+}
+
 }
 
 bool ScDPCache::InitFromDoc(ScDocument* pDoc, const ScRange& rRange)
@@ -316,9 +335,9 @@ bool ScDPCache::InitFromDoc(ScDocument* pDoc, const ScRange& rRange)
 
     for (sal_uInt16 nCol = nStartCol; nCol <= nEndCol; ++nCol)
     {
-        AddLabel(ScDPItemData(pDoc, nCol, nStartRow, nDocTab, true).GetString());
+        AddLabel(createLabelString(pDoc, nCol, nStartRow, nDocTab));
         for (SCROW nRow = nStartRow + 1; nRow <= nEndRow; ++nRow)
-            AddData(nCol - nStartCol, new ScDPItemData(pDoc, nCol, nRow, nDocTab, false));
+            AddData(nCol - nStartCol, new ScDPItemData(pDoc, nCol, nRow, nDocTab));
     }
     return true;
 }