[Xtensa] Fix lowering funnel shift left.

Author: andreisfr

llvm/lib/Target/Xtensa/XtensaISelLowering.cpp

@@ -1793,12 +1793,16 @@ SDValue XtensaTargetLowering::LowerFunnelShift(SDValue Op,
   bool IsFSHR = Op.getOpcode() == ISD::FSHR;
   assert((VT == MVT::i32) && "Unexpected funnel shift type!");
 
+  SDValue SetSAR;
+
   if (!IsFSHR) {
-    Shamt = DAG.getNode(ISD::SUB, DL, MVT::i32,
-                        DAG.getConstant(32, DL, MVT::i32), Shamt);
+    SetSAR = DAG.getNode(XtensaISD::SSL, DL,
+                         MVT::Glue, Shamt);
+  } else {
+    SetSAR = DAG.getNode(XtensaISD::SSR, DL,
+                         MVT::Glue, Shamt);
   }
-  SDValue SetSAR = DAG.getNode(XtensaISD::SSR, DL,
-                               MVT::Glue, Shamt);
+
   return DAG.getNode(XtensaISD::SRC, DL, VT, Op0, Op1, SetSAR);
 }
 

llvm/test/CodeGen/Xtensa/funnel-shift.ll

@@ -11,9 +11,7 @@ entry:
 
 define dso_local i32 @test_fshl(i32 %value1, i32 %value2, i32 %shift) nounwind {
 ; CHECK-LABEL: @test_fshl
-; CHECK: movi.n a8, 32
-; CHECK: sub a8, a8, a4
-; CHECK: ssr a8
+; CHECK: ssl a4
 ; CHECK: src a2, a2, a3
 entry:
   %0 = tail call i32 @llvm.fshl.i32(i32 %value1, i32 %value2, i32 %shift)