From ca52e101f76eb1c51060efbeac52c167091bbee7 Mon Sep 17 00:00:00 2001
From: Nirav Dave <niravd@google.com>
Date: Tue, 8 Aug 2017 20:01:18 +0000
Subject: [PATCH] [DAG] Introduce peekThroughBitcast function. NFCI.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310405 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 37 +++++++++---------------
 1 file changed, 14 insertions(+), 23 deletions(-)

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 6320d60b5bb..fd73802cceb 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -12419,6 +12419,12 @@ bool DAGCombiner::isMulAddWithConstProfitable(SDNode *MulNode,
   return false;
 }
 
+static SDValue peekThroughBitcast(SDValue V) {
+  while (V.getOpcode() == ISD::BITCAST)
+    V = V.getOperand(0);
+  return V;
+}
+
 SDValue DAGCombiner::getMergeStoreChains(SmallVectorImpl<MemOpLink> &StoreNodes,
                                          unsigned NumStores) {
   SmallVector<SDValue, 8> Chains;
@@ -14614,8 +14620,7 @@ static SDValue combineConcatVectorOfExtracts(SDNode *N, SelectionDAG &DAG) {
 
   for (SDValue Op : N->ops()) {
     // Peek through any bitcast.
-    while (Op.getOpcode() == ISD::BITCAST)
-      Op = Op.getOperand(0);
+    Op = peekThroughBitcast(Op);
 
     // UNDEF nodes convert to UNDEF shuffle mask values.
     if (Op.isUndef()) {
@@ -14634,8 +14639,7 @@ static SDValue combineConcatVectorOfExtracts(SDNode *N, SelectionDAG &DAG) {
     EVT ExtVT = ExtVec.getValueType();
 
     // Peek through any bitcast.
-    while (ExtVec.getOpcode() == ISD::BITCAST)
-      ExtVec = ExtVec.getOperand(0);
+    ExtVec = peekThroughBitcast(ExtVec);
 
     // UNDEF nodes convert to UNDEF shuffle mask values.
     if (ExtVec.isUndef()) {
@@ -14860,9 +14864,7 @@ static SDValue narrowExtractedVectorBinOp(SDNode *Extract, SelectionDAG &DAG) {
 
   // We are looking for an optionally bitcasted wide vector binary operator
   // feeding an extract subvector.
-  SDValue BinOp = Extract->getOperand(0);
-  if (BinOp.getOpcode() == ISD::BITCAST)
-    BinOp = BinOp.getOperand(0);
+  SDValue BinOp = peekThroughBitcast(Extract->getOperand(0));
 
   // TODO: The motivating case for this transform is an x86 AVX1 target. That
   // target has temptingly almost legal versions of bitwise logic ops in 256-bit
@@ -14886,13 +14888,8 @@ static SDValue narrowExtractedVectorBinOp(SDNode *Extract, SelectionDAG &DAG) {
     return SDValue();
 
   // Peek through bitcasts of the binary operator operands if needed.
-  SDValue LHS = BinOp.getOperand(0);
-  if (LHS.getOpcode() == ISD::BITCAST)
-    LHS = LHS.getOperand(0);
-
-  SDValue RHS = BinOp.getOperand(1);
-  if (RHS.getOpcode() == ISD::BITCAST)
-    RHS = RHS.getOperand(0);
+  SDValue LHS = peekThroughBitcast(BinOp.getOperand(0));
+  SDValue RHS = peekThroughBitcast(BinOp.getOperand(1));
 
   // We need at least one concatenation operation of a binop operand to make
   // this transform worthwhile. The concat must double the input vector sizes.
@@ -14991,8 +14988,7 @@ SDValue DAGCombiner::visitEXTRACT_SUBVECTOR(SDNode* N) {
   }
 
   // Skip bitcasting
-  if (V->getOpcode() == ISD::BITCAST)
-    V = V.getOperand(0);
+  V = peekThroughBitcast(V);
 
   if (V->getOpcode() == ISD::INSERT_SUBVECTOR) {
     // Handle only simple case where vector being inserted and vector
@@ -15349,9 +15345,7 @@ static SDValue combineTruncationShuffle(ShuffleVectorSDNode *SVN,
   if (!VT.isInteger() || IsBigEndian)
     return SDValue();
 
-  SDValue N0 = SVN->getOperand(0);
-  while (N0.getOpcode() == ISD::BITCAST)
-    N0 = N0.getOperand(0);
+  SDValue N0 = peekThroughBitcast(SVN->getOperand(0));
 
   unsigned Opcode = N0.getOpcode();
   if (Opcode != ISD::ANY_EXTEND_VECTOR_INREG &&
@@ -15937,7 +15931,7 @@ SDValue DAGCombiner::visitFP16_TO_FP(SDNode *N) {
 SDValue DAGCombiner::XformToShuffleWithZero(SDNode *N) {
   EVT VT = N->getValueType(0);
   SDValue LHS = N->getOperand(0);
-  SDValue RHS = N->getOperand(1);
+  SDValue RHS = peekThroughBitcast(N->getOperand(1));
   SDLoc DL(N);
 
   // Make sure we're not running after operation legalization where it
@@ -15948,9 +15942,6 @@ SDValue DAGCombiner::XformToShuffleWithZero(SDNode *N) {
   if (N->getOpcode() != ISD::AND)
     return SDValue();
 
-  if (RHS.getOpcode() == ISD::BITCAST)
-    RHS = RHS.getOperand(0);
-
   if (RHS.getOpcode() != ISD::BUILD_VECTOR)
     return SDValue();
 
-- 
2.50.1