From ee09c63e57866e6d47964f0094a7d884ae99b7ef Mon Sep 17 00:00:00 2001
From: Martin Storsjo <martin@martin.st>
Date: Sat, 19 Aug 2017 20:26:51 +0000
Subject: [PATCH] [ARM] Factorize the calculation of WhichResult in isV*Mask.
 NFC.

Differential Revision: https://reviews.llvm.org/D36930

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@311260 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/ARM/ARMISelLowering.cpp | 37 +++++++++++-------------------
 1 file changed, 13 insertions(+), 24 deletions(-)

diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index 320d7ccfbc2..63a96ccde78 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -5800,6 +5800,13 @@ static bool isVTBLMask(ArrayRef<int> M, EVT VT) {
   return VT == MVT::v8i8 && M.size() == 8;
 }
 
+static unsigned SelectPairHalf(unsigned Elements, ArrayRef<int> Mask,
+                               unsigned Index) {
+  if (Mask.size() == Elements * 2)
+    return Index / Elements;
+  return Mask[Index] == 0 ? 0 : 1;
+}
+
 // Checks whether the shuffle mask represents a vector transpose (VTRN) by
 // checking that pairs of elements in the shuffle mask represent the same index
 // in each vector, incrementing the expected index by 2 at each step.
@@ -5836,10 +5843,7 @@ static bool isVTRNMask(ArrayRef<int> M, EVT VT, unsigned &WhichResult) {
   // element is undefined, e.g. [-1, 4, 2, 6] will be rejected, because only
   // M[0] is used to determine WhichResult
   for (unsigned i = 0; i < M.size(); i += NumElts) {
-    if (M.size() == NumElts * 2)
-      WhichResult = i / NumElts;
-    else
-      WhichResult = M[i] == 0 ? 0 : 1;
+    WhichResult = SelectPairHalf(NumElts, M, i);
     for (unsigned j = 0; j < NumElts; j += 2) {
       if ((M[i+j] >= 0 && (unsigned) M[i+j] != j + WhichResult) ||
           (M[i+j+1] >= 0 && (unsigned) M[i+j+1] != j + NumElts + WhichResult))
@@ -5866,10 +5870,7 @@ static bool isVTRN_v_undef_Mask(ArrayRef<int> M, EVT VT, unsigned &WhichResult){
     return false;
 
   for (unsigned i = 0; i < M.size(); i += NumElts) {
-    if (M.size() == NumElts * 2)
-      WhichResult = i / NumElts;
-    else
-      WhichResult = M[i] == 0 ? 0 : 1;
+    WhichResult = SelectPairHalf(NumElts, M, i);
     for (unsigned j = 0; j < NumElts; j += 2) {
       if ((M[i+j] >= 0 && (unsigned) M[i+j] != j + WhichResult) ||
           (M[i+j+1] >= 0 && (unsigned) M[i+j+1] != j + WhichResult))
@@ -5901,10 +5902,7 @@ static bool isVUZPMask(ArrayRef<int> M, EVT VT, unsigned &WhichResult) {
     return false;
 
   for (unsigned i = 0; i < M.size(); i += NumElts) {
-    if (M.size() == NumElts * 2)
-      WhichResult = i / NumElts;
-    else
-      WhichResult = M[i] == 0 ? 0 : 1;
+    WhichResult = SelectPairHalf(NumElts, M, i);
     for (unsigned j = 0; j < NumElts; ++j) {
       if (M[i+j] >= 0 && (unsigned) M[i+j] != 2 * j + WhichResult)
         return false;
@@ -5935,10 +5933,7 @@ static bool isVUZP_v_undef_Mask(ArrayRef<int> M, EVT VT, unsigned &WhichResult){
 
   unsigned Half = NumElts / 2;
   for (unsigned i = 0; i < M.size(); i += NumElts) {
-    if (M.size() == NumElts * 2)
-      WhichResult = i / NumElts;
-    else
-      WhichResult = M[i] == 0 ? 0 : 1;
+    WhichResult = SelectPairHalf(NumElts, M, i);
     for (unsigned j = 0; j < NumElts; j += Half) {
       unsigned Idx = WhichResult;
       for (unsigned k = 0; k < Half; ++k) {
@@ -5978,10 +5973,7 @@ static bool isVZIPMask(ArrayRef<int> M, EVT VT, unsigned &WhichResult) {
     return false;
 
   for (unsigned i = 0; i < M.size(); i += NumElts) {
-    if (M.size() == NumElts * 2)
-      WhichResult = i / NumElts;
-    else
-      WhichResult = M[i] == 0 ? 0 : 1;
+    WhichResult = SelectPairHalf(NumElts, M, i);
     unsigned Idx = WhichResult * NumElts / 2;
     for (unsigned j = 0; j < NumElts; j += 2) {
       if ((M[i+j] >= 0 && (unsigned) M[i+j] != Idx) ||
@@ -6014,10 +6006,7 @@ static bool isVZIP_v_undef_Mask(ArrayRef<int> M, EVT VT, unsigned &WhichResult){
     return false;
 
   for (unsigned i = 0; i < M.size(); i += NumElts) {
-    if (M.size() == NumElts * 2)
-      WhichResult = i / NumElts;
-    else
-      WhichResult = M[i] == 0 ? 0 : 1;
+    WhichResult = SelectPairHalf(NumElts, M, i);
     unsigned Idx = WhichResult * NumElts / 2;
     for (unsigned j = 0; j < NumElts; j += 2) {
       if ((M[i+j] >= 0 && (unsigned) M[i+j] != Idx) ||
-- 
2.40.0