[InstCombine] Combine trunc (lshr X, BW-1) to i1 --> icmp slt X, 0 (#142593)

Author: mayanksolanki393

llvm/test/Transforms/InstCombine/logical-select.ll

@@ -807,9 +807,9 @@ define <2 x i16> @bitcast_vec_cond_commute3(<4 x i8> %cond, <2 x i16> %pc, <2 x
 ; CHECK-LABEL: @bitcast_vec_cond_commute3(
 ; CHECK-NEXT:    [[C:%.*]] = mul <2 x i16> [[PC:%.*]], [[PC]]
 ; CHECK-NEXT:    [[D:%.*]] = mul <2 x i16> [[PD:%.*]], [[PD]]
+; CHECK-NEXT:    [[DOTNOT2:%.*]] = icmp slt <4 x i8> [[COND:%.*]], zeroinitializer
 ; CHECK-NEXT:    [[TMP1:%.*]] = bitcast <2 x i16> [[D]] to <4 x i8>
 ; CHECK-NEXT:    [[TMP2:%.*]] = bitcast <2 x i16> [[C]] to <4 x i8>
-; CHECK-NEXT:    [[DOTNOT2:%.*]] = icmp slt <4 x i8> [[COND:%.*]], zeroinitializer
 ; CHECK-NEXT:    [[TMP3:%.*]] = select <4 x i1> [[DOTNOT2]], <4 x i8> [[TMP1]], <4 x i8> [[TMP2]]
 ; CHECK-NEXT:    [[R:%.*]] = bitcast <4 x i8> [[TMP3]] to <2 x i16>
 ; CHECK-NEXT:    ret <2 x i16> [[R]]
@@ -1069,8 +1069,8 @@ define <2 x i1> @not_d_bools_vector_poison(<2 x i1> %c, <2 x i1> %x, <2 x i1> %y
 
 define i32 @not_d_allSignBits(i32 %cond, i32 %tval, i32 %fval) {
 ; CHECK-LABEL: @not_d_allSignBits(
-; CHECK-NEXT:    [[TMP1:%.*]] = xor i32 [[FVAL:%.*]], -1
 ; CHECK-NEXT:    [[DOTNOT2:%.*]] = icmp slt i32 [[COND:%.*]], 0
+; CHECK-NEXT:    [[TMP1:%.*]] = xor i32 [[FVAL:%.*]], -1
 ; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[DOTNOT2]], i32 [[TVAL:%.*]], i32 [[TMP1]]
 ; CHECK-NEXT:    ret i32 [[SEL]]
 ;