add nopoison back

Author: el-ev

llvm/lib/Transforms/Scalar/ConstraintElimination.cpp

@@ -1134,7 +1134,6 @@ void State::addInfoFor(BasicBlock &BB) {
     case Intrinsic::smin:
     case Intrinsic::smax:
     case Intrinsic::usub_sat:
-      // TODO: handle llvm.abs as well
       WorkList.push_back(
           FactOrCheck::getCheck(DT.getNode(&BB), cast<CallInst>(&I)));
       // TODO: Check if it is possible to instead only added the min/max facts

llvm/test/Transforms/ConstraintElimination/abs.ll

@@ -72,10 +72,8 @@ define i1 @abs_plus_one_unsigned_greater_or_equal_nonnegative_arg(i32 %arg) {
 ; CHECK-SAME: i32 [[ARG:%.*]]) {
 ; CHECK-NEXT:    [[CMP_ARG_NONNEGATIVE:%.*]] = icmp sge i32 [[ARG]], 0
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[CMP_ARG_NONNEGATIVE]])
-; CHECK-NEXT:    [[ABS:%.*]] = tail call i32 @llvm.abs.i32(i32 [[ARG]], i1 true)
-; CHECK-NEXT:    [[ABS_PLUS_ONE:%.*]] = add nuw i32 [[ABS]], 1
-; CHECK-NEXT:    [[CMP:%.*]] = icmp uge i32 [[ABS_PLUS_ONE]], [[ARG]]
-; CHECK-NEXT:    ret i1 [[CMP]]
+; CHECK-NEXT:    [[ABS_PLUS_ONE:%.*]] = add nuw i32 [[ARG]], 1
+; CHECK-NEXT:    ret i1 true
 ;
   %cmp_arg_nonnegative = icmp sge i32 %arg, 0
   call void @llvm.assume(i1 %cmp_arg_nonnegative)
@@ -155,9 +153,7 @@ define i1 @abs_is_nonnegative_int_min_is_poison(i32 %arg) {
 
 define i1 @abs_is_nonnegative_constant_arg() {
 ; CHECK-LABEL: define i1 @abs_is_nonnegative_constant_arg() {
-; CHECK-NEXT:    [[ABS:%.*]] = tail call i32 @llvm.abs.i32(i32 -3, i1 true)
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sge i32 [[ABS]], 0
-; CHECK-NEXT:    ret i1 [[CMP]]
+; CHECK-NEXT:    ret i1 true
 ;
   %abs = tail call i32 @llvm.abs.i32(i32 -3, i1 true)
   %cmp = icmp sge i32 %abs, 0