[AggressiveInstCombine] use m_Deferred on funnel shift(NFC)

[khei4]

Summary

remove TODO by using m_Deferred on foldGuardedFunnelShift

[nikic]

LGTM

llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp

static bool foldGuardedFunnelShift(Instruction &I, const DominatorTree &DT) {
   // would be expanded back into math/shift/logic ops).
   if (!isPowerOf2_32(I.getType()->getScalarSizeInBits()))
     return false;
 
   // Match V to funnel shift left/right and capture the source operands and
   // shift amount.
   auto matchFunnelShift = [](Value *V, Value *&ShVal0, Value *&ShVal1,
                              Value *&ShAmt) {
-    Value *SubAmt;
     unsigned Width = V->getType()->getScalarSizeInBits();
 
     // fshl(ShVal0, ShVal1, ShAmt)
     //  == (ShVal0 << ShAmt) | (ShVal1 >> (Width -ShAmt))
     if (match(V, m_OneUse(m_c_Or(
                      m_Shl(m_Value(ShVal0), m_Value(ShAmt)),
                      m_LShr(m_Value(ShVal1),
-                            m_Sub(m_SpecificInt(Width), m_Value(SubAmt))))))) {
-      if (ShAmt == SubAmt) // TODO: Use m_Specific
+                            m_Sub(m_SpecificInt(Width), m_Deferred(ShAmt))))))) {
         return Intrinsic::fshl;
     }
 
     // fshr(ShVal0, ShVal1, ShAmt)
     //  == (ShVal0 >> ShAmt) | (ShVal1 << (Width - ShAmt))
     if (match(V,
               m_OneUse(m_c_Or(m_Shl(m_Value(ShVal0), m_Sub(m_SpecificInt(Width),
-                                                           m_Value(SubAmt))),
-                              m_LShr(m_Value(ShVal1), m_Value(ShAmt)))))) {
-      if (ShAmt == SubAmt) // TODO: Use m_Specific
+                                                           m_Value(ShAmt))),
+                              m_LShr(m_Value(ShVal1), m_Deferred(ShAmt)))))) {
         return Intrinsic::fshr;
     }
 
     return Intrinsic::not_intrinsic;
   };
 
   // One phi operand must be a funnel/rotate operation, and the other phi
   // operand must be the source value of that funnel/rotate operation: