llvm/test/Transforms/ConstraintElimination/range_checks.ll

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -passes=constraint-elimination -S %s | FileCheck %s

; Here we can remove range check because:
; length >= min_length (from entry)
; idx < min_length (from in_bounds check)
; therefore, idx < length is trivially true.

define i32 @test_01(ptr %p, ptr %array, i32 %min_length) {
; CHECK-LABEL: @test_01(
; CHECK-NEXT:  entry:
; CHECK-NEXT:    br label [[LOOP:%.*]]
; CHECK:       loop:
; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[BACKEDGE:%.*]] ]
; CHECK-NEXT:    [[ELEM_PTR:%.*]] = getelementptr i32, ptr [[P:%.*]], i32 [[IV]]
; CHECK-NEXT:    [[IDX:%.*]] = load i32, ptr [[ELEM_PTR]], align 4
; CHECK-NEXT:    [[IN_BOUNDS:%.*]] = icmp ult i32 [[IDX]], [[MIN_LENGTH:%.*]]
; CHECK-NEXT:    br i1 [[IN_BOUNDS]], label [[RANGE_CHECK_BLOCK:%.*]], label [[OUT_OF_BOUNDS:%.*]]
; CHECK:       range_check_block:
; CHECK-NEXT:    br i1 true, label [[BACKEDGE]], label [[RANGE_CHECK_FAILED:%.*]]
; CHECK:       backedge:
; CHECK-NEXT:    [[ARR_PTR:%.*]] = getelementptr i32, ptr [[ARRAY:%.*]], i32 [[IDX]]
; CHECK-NEXT:    store i32 [[IV]], ptr [[ARR_PTR]], align 4
; CHECK-NEXT:    [[IV_NEXT]] = add i32 [[IV]], 1
; CHECK-NEXT:    [[LOOP_COND:%.*]] = call i1 @cond()
; CHECK-NEXT:    br i1 [[LOOP_COND]], label [[LOOP]], label [[EXIT:%.*]]
; CHECK:       exit:
; CHECK-NEXT:    [[IV_LCSSA:%.*]] = phi i32 [ [[IV]], [[BACKEDGE]] ]
; CHECK-NEXT:    ret i32 [[IV_LCSSA]]
; CHECK:       out_of_bounds:
; CHECK-NEXT:    ret i32 -1
; CHECK:       range_check_failed:
; CHECK-NEXT:    [[IV_LCSSA_RC:%.*]] = phi i32 [ [[IV]], [[RANGE_CHECK_BLOCK]] ]
; CHECK-NEXT:    call void @failed_range_check(i32 [[IV_LCSSA_RC]])
; CHECK-NEXT:    unreachable
;
entry:
  br label %loop

loop:                                             ; preds = %backedge, %entry
  %iv = phi i32 [ 0, %entry ], [ %iv.next, %backedge ]
  %elem_ptr = getelementptr i32, ptr %p, i32 %iv
  %idx = load i32, ptr %elem_ptr, align 4
  %in_bounds = icmp ult i32 %idx, %min_length
  br i1 %in_bounds, label %range_check_block, label %out_of_bounds

range_check_block:                                ; preds = %loop
  %range_check = icmp ult i32 %idx, %min_length
  br i1 %range_check, label %backedge, label %range_check_failed

backedge:                                         ; preds = %range_check_block
  %arr_ptr = getelementptr i32, ptr %array, i32 %idx
  store i32 %iv, ptr %arr_ptr, align 4
  %iv.next = add i32 %iv, 1
  %loop_cond = call i1 @cond()
  br i1 %loop_cond, label %loop, label %exit

exit:                                             ; preds = %backedge
  %iv.lcssa = phi i32 [ %iv, %backedge ]
  ret i32 %iv.lcssa

out_of_bounds:                                    ; preds = %loop
  ret i32 -1

range_check_failed:                               ; preds = %range_check_block
  %iv.lcssa.rc = phi i32 [ %iv, %range_check_block ]
  call void @failed_range_check(i32 %iv.lcssa.rc)
  unreachable
}

define i32 @test_02(ptr %p, ptr %array, i32 %length, i32 %min_length) {
; CHECK-LABEL: @test_02(
; CHECK-NEXT:  entry:
; CHECK-NEXT:    [[LENGTH_CHECK:%.*]] = icmp uge i32 [[LENGTH:%.*]], [[MIN_LENGTH:%.*]]
; CHECK-NEXT:    br i1 [[LENGTH_CHECK]], label [[LOOP:%.*]], label [[FAILED:%.*]]
; CHECK:       loop:
; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[BACKEDGE:%.*]] ]
; CHECK-NEXT:    [[ELEM_PTR:%.*]] = getelementptr i32, ptr [[P:%.*]], i32 [[IV]]
; CHECK-NEXT:    [[IDX:%.*]] = load i32, ptr [[ELEM_PTR]], align 4
; CHECK-NEXT:    [[IN_BOUNDS:%.*]] = icmp ult i32 [[IDX]], [[MIN_LENGTH]]
; CHECK-NEXT:    br i1 [[IN_BOUNDS]], label [[RANGE_CHECK_BLOCK:%.*]], label [[OUT_OF_BOUNDS:%.*]]
; CHECK:       range_check_block:
; CHECK-NEXT:    br i1 true, label [[BACKEDGE]], label [[RANGE_CHECK_FAILED:%.*]]
; CHECK:       backedge:
; CHECK-NEXT:    [[ARR_PTR:%.*]] = getelementptr i32, ptr [[ARRAY:%.*]], i32 [[IDX]]
; CHECK-NEXT:    store i32 [[IV]], ptr [[ARR_PTR]], align 4
; CHECK-NEXT:    [[IV_NEXT]] = add i32 [[IV]], 1
; CHECK-NEXT:    [[LOOP_COND:%.*]] = call i1 @cond()
; CHECK-NEXT:    br i1 [[LOOP_COND]], label [[LOOP]], label [[EXIT:%.*]]
; CHECK:       exit:
; CHECK-NEXT:    [[IV_LCSSA:%.*]] = phi i32 [ [[IV]], [[BACKEDGE]] ]
; CHECK-NEXT:    ret i32 [[IV_LCSSA]]
; CHECK:       failed:
; CHECK-NEXT:    unreachable
; CHECK:       out_of_bounds:
; CHECK-NEXT:    ret i32 -1
; CHECK:       range_check_failed:
; CHECK-NEXT:    [[IV_LCSSA_RC:%.*]] = phi i32 [ [[IV]], [[RANGE_CHECK_BLOCK]] ]
; CHECK-NEXT:    call void @failed_range_check(i32 [[IV_LCSSA_RC]])
; CHECK-NEXT:    unreachable
;
entry:
  %length_check = icmp uge i32 %length, %min_length
  br i1 %length_check, label %loop, label %failed

loop:                                             ; preds = %backedge, %entry
  %iv = phi i32 [ 0, %entry ], [ %iv.next, %backedge ]
  %elem_ptr = getelementptr i32, ptr %p, i32 %iv
  %idx = load i32, ptr %elem_ptr, align 4
  %in_bounds = icmp ult i32 %idx, %min_length
  br i1 %in_bounds, label %range_check_block, label %out_of_bounds

range_check_block:                                ; preds = %loop
  %range_check = icmp ult i32 %idx, %length
  br i1 %range_check, label %backedge, label %range_check_failed

backedge:                                         ; preds = %range_check_block
  %arr_ptr = getelementptr i32, ptr %array, i32 %idx
  store i32 %iv, ptr %arr_ptr, align 4
  %iv.next = add i32 %iv, 1
  %loop_cond = call i1 @cond()
  br i1 %loop_cond, label %loop, label %exit

exit:                                             ; preds = %backedge
  %iv.lcssa = phi i32 [ %iv, %backedge ]
  ret i32 %iv.lcssa

failed:                                           ; preds = %entry
  unreachable

out_of_bounds:                                    ; preds = %loop
  ret i32 -1

range_check_failed:                               ; preds = %range_check_block
  %iv.lcssa.rc = phi i32 [ %iv, %range_check_block ]
  call void @failed_range_check(i32 %iv.lcssa.rc)
  unreachable
}

declare i1 @cond()

declare void @failed_range_check(i32)