[DAG] BaseIndexOffset::equalBaseIndex - early out on failed matches. NFCI.

If we successfully cast only the first base node as GlobalAddressSDNode / ConstantPoolSDNode / FrameIndexSDNode then we can early out as we know that base won't cast as a later type.

Noticed while investigating profiles for potential compile time improvements.

Author: RKSimon

llvm/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp

@@ -38,15 +38,18 @@ bool BaseIndexOffset::equalBaseIndex(const BaseIndexOffset &Other,
       return true;
 
     // Match GlobalAddresses
-    if (auto *A = dyn_cast<GlobalAddressSDNode>(Base))
+    if (auto *A = dyn_cast<GlobalAddressSDNode>(Base)) {
       if (auto *B = dyn_cast<GlobalAddressSDNode>(Other.Base))
         if (A->getGlobal() == B->getGlobal()) {
           Off += B->getOffset() - A->getOffset();
           return true;
         }
 
+      return false;
+    }
+
     // Match Constants
-    if (auto *A = dyn_cast<ConstantPoolSDNode>(Base))
+    if (auto *A = dyn_cast<ConstantPoolSDNode>(Base)) {
       if (auto *B = dyn_cast<ConstantPoolSDNode>(Other.Base)) {
         bool IsMatch =
             A->isMachineConstantPoolEntry() == B->isMachineConstantPoolEntry();
@@ -62,7 +65,8 @@ bool BaseIndexOffset::equalBaseIndex(const BaseIndexOffset &Other,
         }
       }
 
-    const MachineFrameInfo &MFI = DAG.getMachineFunction().getFrameInfo();
+      return false;
+    }
 
     // Match FrameIndexes.
     if (auto *A = dyn_cast<FrameIndexSDNode>(Base))
@@ -73,6 +77,7 @@ bool BaseIndexOffset::equalBaseIndex(const BaseIndexOffset &Other,
         // Non-equal FrameIndexes - If both frame indices are fixed
         // we know their relative offsets and can compare them. Otherwise
         // we must be conservative.
+        const MachineFrameInfo &MFI = DAG.getMachineFunction().getFrameInfo();
         if (MFI.isFixedObjectIndex(A->getIndex()) &&
             MFI.isFixedObjectIndex(B->getIndex())) {
           Off += MFI.getObjectOffset(B->getIndex()) -
@@ -81,6 +86,7 @@ bool BaseIndexOffset::equalBaseIndex(const BaseIndexOffset &Other,
         }
       }
   }
+
   return false;
 }