[VP][DAGCombine] Use simplifySelect when combining vp.select.

Author: AinsleySnow

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

@@ -12056,6 +12056,13 @@ SDValue DAGCombiner::foldVSelectOfConstants(SDNode *N) {
 }
 
 SDValue DAGCombiner::visitVP_SELECT(SDNode *N) {
+  SDValue N0 = N->getOperand(0);
+  SDValue N1 = N->getOperand(1);
+  SDValue N2 = N->getOperand(2);
+
+  if (SDValue V = DAG.simplifySelect(N0, N1, N2))
+    return V;
+
   if (SDValue V = foldBoolSelectToLogic<VPMatchContext>(N, DAG))
     return V;
 

llvm/test/CodeGen/RISCV/rvv/vselect-vp.ll

@@ -829,10 +829,7 @@ define <vscale x 2 x i1> @select_cond_x_cond(<vscale x 2 x i1> %x, <vscale x 2 x
 define <vscale x 2 x i1> @select_undef_T_F(<vscale x 2 x i1> %x, <vscale x 2 x i1> %y, i32 zeroext %evl) {
 ; CHECK-LABEL: select_undef_T_F:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    vsetvli zero, a0, e8, mf4, ta, ma
-; CHECK-NEXT:    vmandn.mm v8, v8, v8
-; CHECK-NEXT:    vmand.mm v9, v0, v8
-; CHECK-NEXT:    vmor.mm v0, v9, v8
+; CHECK-NEXT:    vmv1r.v v0, v8
 ; CHECK-NEXT:    ret
   %a = call <vscale x 2 x i1> @llvm.vp.select.nxv2i1(<vscale x 2 x i1> poison, <vscale x 2 x i1> %x, <vscale x 2 x i1> %y, i32 %evl)
   ret <vscale x 2 x i1> %a
@@ -841,8 +838,6 @@ define <vscale x 2 x i1> @select_undef_T_F(<vscale x 2 x i1> %x, <vscale x 2 x i
 define <vscale x 2 x i1> @select_undef_undef_F(<vscale x 2 x i1> %x, i32 zeroext %evl) {
 ; CHECK-LABEL: select_undef_undef_F:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    vsetvli zero, a0, e8, mf4, ta, ma
-; CHECK-NEXT:    vmor.mm v0, v8, v0
 ; CHECK-NEXT:    ret
   %a = call <vscale x 2 x i1> @llvm.vp.select.nxv2i1(<vscale x 2 x i1> poison, <vscale x 2 x i1> undef, <vscale x 2 x i1> %x, i32 %evl)
   ret <vscale x 2 x i1> %a
@@ -851,10 +846,7 @@ define <vscale x 2 x i1> @select_undef_undef_F(<vscale x 2 x i1> %x, i32 zeroext
 define <vscale x 2 x i1> @select_unknown_undef_F(<vscale x 2 x i1> %x, <vscale x 2 x i1> %y, i32 zeroext %evl) {
 ; CHECK-LABEL: select_unknown_undef_F:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    vsetvli zero, a0, e8, mf4, ta, ma
-; CHECK-NEXT:    vmandn.mm v8, v8, v0
-; CHECK-NEXT:    vmand.mm v9, v8, v0
-; CHECK-NEXT:    vmor.mm v0, v9, v8
+; CHECK-NEXT:    vmv1r.v v0, v8
 ; CHECK-NEXT:    ret
   %a = call <vscale x 2 x i1> @llvm.vp.select.nxv2i1(<vscale x 2 x i1> %x, <vscale x 2 x i1> undef, <vscale x 2 x i1> %y, i32 %evl)
   ret <vscale x 2 x i1> %a
@@ -863,10 +855,7 @@ define <vscale x 2 x i1> @select_unknown_undef_F(<vscale x 2 x i1> %x, <vscale x
 define <vscale x 2 x i1> @select_unknown_T_undef(<vscale x 2 x i1> %x, <vscale x 2 x i1> %y, i32 zeroext %evl) {
 ; CHECK-LABEL: select_unknown_T_undef:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    vsetvli zero, a0, e8, mf4, ta, ma
-; CHECK-NEXT:    vmandn.mm v9, v8, v0
-; CHECK-NEXT:    vmand.mm v8, v8, v0
-; CHECK-NEXT:    vmor.mm v0, v8, v9
+; CHECK-NEXT:    vmv1r.v v0, v8
 ; CHECK-NEXT:    ret
   %a = call <vscale x 2 x i1> @llvm.vp.select.nxv2i1(<vscale x 2 x i1> %x, <vscale x 2 x i1> %y, <vscale x 2 x i1> poison, i32 %evl)
   ret <vscale x 2 x i1> %a
@@ -875,12 +864,7 @@ define <vscale x 2 x i1> @select_unknown_T_undef(<vscale x 2 x i1> %x, <vscale x
 define <vscale x 2 x i1> @select_false_T_F(<vscale x 2 x i1> %x, <vscale x 2 x i1> %y, <vscale x 2 x i1> %z, i32 zeroext %evl) {
 ; CHECK-LABEL: select_false_T_F:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    vsetvli a1, zero, e8, mf4, ta, ma
-; CHECK-NEXT:    vmclr.m v10
-; CHECK-NEXT:    vsetvli zero, a0, e8, mf4, ta, ma
-; CHECK-NEXT:    vmandn.mm v9, v9, v10
-; CHECK-NEXT:    vmand.mm v8, v8, v10
-; CHECK-NEXT:    vmor.mm v0, v8, v9
+; CHECK-NEXT:    vmv1r.v v0, v9
 ; CHECK-NEXT:    ret
   %a = call <vscale x 2 x i1> @llvm.vp.select.nxv2i1(<vscale x 2 x i1> zeroinitializer, <vscale x 2 x i1> %y, <vscale x 2 x i1> %z, i32 %evl)
   ret <vscale x 2 x i1> %a
@@ -889,10 +873,7 @@ define <vscale x 2 x i1> @select_false_T_F(<vscale x 2 x i1> %x, <vscale x 2 x i
 define <vscale x 2 x i1> @select_unknown_T_T(<vscale x 2 x i1> %x, <vscale x 2 x i1> %y, i32 zeroext %evl) {
 ; CHECK-LABEL: select_unknown_T_T:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    vsetvli zero, a0, e8, mf4, ta, ma
-; CHECK-NEXT:    vmandn.mm v9, v8, v0
-; CHECK-NEXT:    vmand.mm v8, v8, v0
-; CHECK-NEXT:    vmor.mm v0, v8, v9
+; CHECK-NEXT:    vmv1r.v v0, v8
 ; CHECK-NEXT:    ret
   %a = call <vscale x 2 x i1> @llvm.vp.select.nxv2i1(<vscale x 2 x i1> %x, <vscale x 2 x i1> %y, <vscale x 2 x i1> %y, i32 %evl)
   ret <vscale x 2 x i1> %a