[CSKY] Optimize conditional select with CLRT/CLRF

llvm/lib/Target/CSKY/CSKYInstrInfo.td

multiclass MOVTF32Pat1<PatFrag cond0, PatFrag cond1, Instruction cmp_inst,
   def : Pat<(select (i32 (cond1 GPR:$rs1, GPR:$rs2)), GPR:$rx, GPR:$false),
             (mov_inst (cmp_inst GPR:$rs2, GPR:$rs1), GPR:$rx, GPR:$false)>;
 }
 
 defm : MOVTF32Pat1<setuge, setule, CMPHS32, MOVT32>;
 defm : MOVTF32Pat1<setult, setugt, CMPHS32, MOVF32>;
 defm : MOVTF32Pat1<setlt, setgt, CMPLT32, MOVT32>;
 defm : MOVTF32Pat1<setge, setle, CMPLT32, MOVF32>;
+
+def : Pat<(select CARRY:$ca, (i32 0), GPR:$other),
+          (CLRT32 CARRY:$ca, GPR:$other)>;
+def : Pat<(select CARRY:$ca, GPR:$other, (i32 0)),
+          (CLRF32 CARRY:$ca, GPR:$other)>;
 }
 
 // Constant materialize patterns.
 let Predicates = [iHasE2] in
   def : Pat<(i32 imm:$imm),
             (ORI32 (MOVIH32 (uimm32_hi16 imm:$imm)), (uimm32_lo16 imm:$imm))>;
 
 // Other operations.

llvm/test/CodeGen/CSKY/select.ll

 entry:
   %ret = select i1 %c, i32 %m, i32 %n
   ret i32 %ret
 }
 
 define i32 @selectRI_0_if_true(i1 %c, i32 %q) {
 ; CHECK-LABEL: selectRI_0_if_true:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    movi16 a2, 0
 ; CHECK-NEXT:    btsti16 a0, 0
-; CHECK-NEXT:    movt32 a1, a2
+; CHECK-NEXT:    clrt32 a1
 ; CHECK-NEXT:    mov16 a0, a1
 ; CHECK-NEXT:    rts16
 ;
 ; GENERIC-LABEL: selectRI_0_if_true:
 ; GENERIC:       # %bb.0:
 ; GENERIC-NEXT:    .cfi_def_cfa_offset 0
 ; GENERIC-NEXT:    subi16 sp, sp, 4
 ; GENERIC-NEXT:    .cfi_def_cfa_offset 4
 ; GENERIC-NEXT:    mov16 a2, a0
 ; GENERIC-NEXT:    movi16 a0, 0
 ; GENERIC-NEXT:    btsti16 a2, 0
 ; GENERIC-NEXT:    bt16 .LBB4_2
 ; GENERIC-NEXT:  # %bb.1:
 ; GENERIC-NEXT:    mov16 a0, a1
 ; GENERIC-NEXT:  .LBB4_2:
 ; GENERIC-NEXT:    addi16 sp, sp, 4
 ; GENERIC-NEXT:    rts16
   %ret = select i1 %c, i32 0, i32 %q
   ret i32 %ret
 }
 
 define i32 @selectRI_0_if_false(i1 %c, i32 %q) {
 ; CHECK-LABEL: selectRI_0_if_false:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    movi16 a2, 0
 ; CHECK-NEXT:    btsti16 a0, 0
-; CHECK-NEXT:    movt32 a2, a1
-; CHECK-NEXT:    mov16 a0, a2
+; CHECK-NEXT:    clrf32 a1
+; CHECK-NEXT:    mov16 a0, a1
 ; CHECK-NEXT:    rts16
 ;
 ; GENERIC-LABEL: selectRI_0_if_false:
 ; GENERIC:       # %bb.0:
 ; GENERIC-NEXT:    .cfi_def_cfa_offset 0
 ; GENERIC-NEXT:    subi16 sp, sp, 4
 ; GENERIC-NEXT:    .cfi_def_cfa_offset 4
 ; GENERIC-NEXT:    btsti16 a0, 0