[DAGCombiner] Updated bswap byte offset variable names to be more descriptive. NFC

As discussed on D32039, use MaskByteOffset to describe the variable and also pull out repeated getOpcode() calls.

llvm-svn: 301193

1 files changed, 15 insertions, 13 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 91a56f81e97..9251bf9f04d 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -3878,27 +3878,29 @@ static bool isBSwapHWordElement(SDValue N, MutableArrayRef<SDNode *> Parts) {
   if (Opc != ISD::AND && Opc != ISD::SHL && Opc != ISD::SRL)
     return false;
 
+  SDValue N0 = N.getOperand(0);
+  unsigned Opc0 = N0.getOpcode();
+
   ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N.getOperand(1));
   if (!N1C)
     return false;
 
-  unsigned Num;
+  unsigned MaskByteOffset;
   switch (N1C->getZExtValue()) {
   default:
     return false;
-  case 0xFF:       Num = 0; break;
-  case 0xFF00:     Num = 1; break;
-  case 0xFF0000:   Num = 2; break;
-  case 0xFF000000: Num = 3; break;
+  case 0xFF:       MaskByteOffset = 0; break;
+  case 0xFF00:     MaskByteOffset = 1; break;
+  case 0xFF0000:   MaskByteOffset = 2; break;
+  case 0xFF000000: MaskByteOffset = 3; break;
   }
 
   // Look for (x & 0xff) << 8 as well as ((x << 8) & 0xff00).
-  SDValue N0 = N.getOperand(0);
   if (Opc == ISD::AND) {
-    if (Num == 0 || Num == 2) {
+    if (MaskByteOffset == 0 || MaskByteOffset == 2) {
       // (x >> 8) & 0xff
       // (x >> 8) & 0xff0000
-      if (N0.getOpcode() != ISD::SRL)
+      if (Opc0 != ISD::SRL)
         return false;
       ConstantSDNode *C = dyn_cast<ConstantSDNode>(N0.getOperand(1));
       if (!C || C->getZExtValue() != 8)
@@ -3906,7 +3908,7 @@ static bool isBSwapHWordElement(SDValue N, MutableArrayRef<SDNode *> Parts) {
     } else {
       // (x << 8) & 0xff00
       // (x << 8) & 0xff000000
-      if (N0.getOpcode() != ISD::SHL)
+      if (Opc0 != ISD::SHL)
         return false;
       ConstantSDNode *C = dyn_cast<ConstantSDNode>(N0.getOperand(1));
       if (!C || C->getZExtValue() != 8)
@@ -3915,7 +3917,7 @@ static bool isBSwapHWordElement(SDValue N, MutableArrayRef<SDNode *> Parts) {
   } else if (Opc == ISD::SHL) {
     // (x & 0xff) << 8
     // (x & 0xff0000) << 8
-    if (Num != 0 && Num != 2)
+    if (MaskByteOffset != 0 && MaskByteOffset != 2)
       return false;
     ConstantSDNode *C = dyn_cast<ConstantSDNode>(N.getOperand(1));
     if (!C || C->getZExtValue() != 8)
@@ -3923,17 +3925,17 @@ static bool isBSwapHWordElement(SDValue N, MutableArrayRef<SDNode *> Parts) {
   } else { // Opc == ISD::SRL
     // (x & 0xff00) >> 8
     // (x & 0xff000000) >> 8
-    if (Num != 1 && Num != 3)
+    if (MaskByteOffset != 1 && MaskByteOffset != 3)
       return false;
     ConstantSDNode *C = dyn_cast<ConstantSDNode>(N.getOperand(1));
     if (!C || C->getZExtValue() != 8)
       return false;
   }
 
-  if (Parts[Num])
+  if (Parts[MaskByteOffset])
     return false;
 
-  Parts[Num] = N0.getOperand(0).getNode();
+  Parts[MaskByteOffset] = N0.getOperand(0).getNode();
   return true;
 }