[llvm] r333660 - [X86][AVX] Add peekThroughEXTRACT_SUBVECTORs helper (NFCI)

[Simon Pilgrim via llvm-commits]

Author: rksimon
Date: Thu May 31 08:15:49 2018
New Revision: 333660

URL: http://llvm.org/viewvc/llvm-project?rev=333660&view=rev
Log:
[X86][AVX] Add peekThroughEXTRACT_SUBVECTORs helper (NFCI)

We often need this for AVX1 128-bit integer ops as they may have been split from a 256-bit source.

Modified:
    llvm/trunk/lib/Target/X86/X86ISelLowering.cpp

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=333660&r1=333659&r2=333660&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Thu May 31 08:15:49 2018
@@ -5422,6 +5422,13 @@ static SDValue peekThroughOneUseBitcasts
   return V;
 }
 
+// Peek through EXTRACT_SUBVECTORs - typically used for AVX1 256-bit intops.
+static SDValue peekThroughEXTRACT_SUBVECTORs(SDValue V) {
+  while (V.getOpcode() == ISD::EXTRACT_SUBVECTOR)
+    V = V.getOperand(0);
+  return V;
+}
+
 static const Constant *getTargetConstantFromNode(SDValue Op) {
   Op = peekThroughBitcasts(Op);
 
@@ -23137,13 +23144,8 @@ static SDValue IsSplatValue(MVT VT, SDVa
   // Check for SUB(SPLAT_BV, SPLAT) cases from rotate patterns.
   if (V.getOpcode() == ISD::SUB &&
       !SupportedVectorVarShift(VT, Subtarget, Opcode)) {
-    // Peek through any EXTRACT_SUBVECTORs.
-    SDValue LHS = V.getOperand(0);
-    SDValue RHS = V.getOperand(1);
-    while (LHS.getOpcode() == ISD::EXTRACT_SUBVECTOR)
-      LHS = LHS.getOperand(0);
-    while (RHS.getOpcode() == ISD::EXTRACT_SUBVECTOR)
-      RHS = RHS.getOperand(0);
+    SDValue LHS = peekThroughEXTRACT_SUBVECTORs(V.getOperand(0));
+    SDValue RHS = peekThroughEXTRACT_SUBVECTORs(V.getOperand(1));
 
     // Ensure that the corresponding splat BV element is not UNDEF.
     BitVector UndefElts;
@@ -23195,9 +23197,7 @@ static SDValue LowerScalarVariableShift(
   unsigned X86OpcV = (Opcode == ISD::SHL) ? X86ISD::VSHL :
     (Opcode == ISD::SRL) ? X86ISD::VSRL : X86ISD::VSRA;
 
-  // Peek through any EXTRACT_SUBVECTORs.
-  while (Amt.getOpcode() == ISD::EXTRACT_SUBVECTOR)
-    Amt = Amt.getOperand(0);
+  Amt = peekThroughEXTRACT_SUBVECTORs(Amt);
 
   if (SupportedVectorShiftWithBaseAmnt(VT, Subtarget, Opcode)) {
     if (SDValue BaseShAmt = IsSplatValue(VT, Amt, dl, DAG, Subtarget, Opcode)) {