Index: llvm/lib/Target/ARM/ARMISelLowering.cpp =================================================================== --- llvm/lib/Target/ARM/ARMISelLowering.cpp +++ llvm/lib/Target/ARM/ARMISelLowering.cpp @@ -13906,6 +13906,18 @@ return DCI.DAG.getNode(ARMISD::PREDICATE_CAST, dl, VT, Op->getOperand(0)); } + // Turn pred_cast(xor x, -1) into xor(pred_cast x, -1), in order to produce + // more VPNOT which might get folded as else predicates. + if (Op.getValueType() == MVT::i32 && Op.getOpcode() == ISD::XOR && + isa(Op.getOperand(1)) && + Op.getConstantOperandAPInt(1).isMask(32)) { + SDValue X = + DCI.DAG.getNode(ARMISD::PREDICATE_CAST, dl, VT, Op->getOperand(0)); + SDValue C = DCI.DAG.getNode(ARMISD::PREDICATE_CAST, dl, VT, + DCI.DAG.getConstant(65535, dl, MVT::i32)); + return DCI.DAG.getNode(ISD::XOR, dl, VT, X, C); + } + // Only the bottom 16 bits of the source register are used. if (Op.getValueType() == MVT::i32) { APInt DemandedMask = APInt::getLowBitsSet(32, 16); Index: llvm/test/CodeGen/Thumb2/mve-pred-constfold.ll =================================================================== --- llvm/test/CodeGen/Thumb2/mve-pred-constfold.ll +++ llvm/test/CodeGen/Thumb2/mve-pred-constfold.ll @@ -52,14 +52,11 @@ ; CHECK-NEXT: .save {r4, r6, r7, lr} ; CHECK-NEXT: push {r4, r6, r7, lr} ; CHECK-NEXT: vmsr p0, r1 -; CHECK-NEXT: mvns r1, r1 -; CHECK-NEXT: vpstt +; CHECK-NEXT: vpsttee ; CHECK-NEXT: vaddvt.s16 r12, q1 ; CHECK-NEXT: vaddvt.s16 r2, q0 -; CHECK-NEXT: vmsr p0, r1 -; CHECK-NEXT: vpstt -; CHECK-NEXT: vaddvt.s16 r4, q1 -; CHECK-NEXT: vaddvt.s16 r6, q0 +; CHECK-NEXT: vaddve.s16 r4, q1 +; CHECK-NEXT: vaddve.s16 r6, q0 ; CHECK-NEXT: stm.w r0, {r2, r6, r12} ; CHECK-NEXT: str r4, [r0, #12] ; CHECK-NEXT: pop {r4, r6, r7, pc} @@ -88,9 +85,9 @@ define arm_aapcs_vfpcc <4 x i32> @xorvpnot_i32(<4 x i32> %acc0, i16 signext %p0) { ; CHECK-LABEL: xorvpnot_i32: ; CHECK: @ %bb.0: @ %entry -; CHECK-NEXT: mvns r0, r0 -; CHECK-NEXT: vmov.i32 q1, #0x0 ; CHECK-NEXT: vmsr p0, r0 +; CHECK-NEXT: vmov.i32 q1, #0x0 +; CHECK-NEXT: vpnot ; CHECK-NEXT: vpsel q0, q0, q1 ; CHECK-NEXT: bx lr entry: @@ -104,9 +101,9 @@ define arm_aapcs_vfpcc <8 x i16> @xorvpnot_i16(<8 x i16> %acc0, i16 signext %p0) { ; CHECK-LABEL: xorvpnot_i16: ; CHECK: @ %bb.0: @ %entry -; CHECK-NEXT: mvns r0, r0 -; CHECK-NEXT: vmov.i32 q1, #0x0 ; CHECK-NEXT: vmsr p0, r0 +; CHECK-NEXT: vmov.i32 q1, #0x0 +; CHECK-NEXT: vpnot ; CHECK-NEXT: vpsel q0, q0, q1 ; CHECK-NEXT: bx lr entry: @@ -120,9 +117,9 @@ define arm_aapcs_vfpcc <16 x i8> @xorvpnot_i8(<16 x i8> %acc0, i16 signext %p0) { ; CHECK-LABEL: xorvpnot_i8: ; CHECK: @ %bb.0: @ %entry -; CHECK-NEXT: mvns r0, r0 -; CHECK-NEXT: vmov.i32 q1, #0x0 ; CHECK-NEXT: vmsr p0, r0 +; CHECK-NEXT: vmov.i32 q1, #0x0 +; CHECK-NEXT: vpnot ; CHECK-NEXT: vpsel q0, q0, q1 ; CHECK-NEXT: bx lr entry: