1; RUN: opt -S -loop-predication -loop-predication-enable-count-down-loop=true < %s 2>&1 | FileCheck %s
2; RUN: opt -S -passes='require<scalar-evolution>,loop(loop-predication)' -loop-predication-enable-count-down-loop=true < %s 2>&1 | FileCheck %s
3
4declare void @llvm.experimental.guard(i1, ...)
5
6define i32 @signed_reverse_loop_n_to_lower_limit(i32* %array, i32 %length, i32 %n, i32 %lowerlimit) {
7; CHECK-LABEL: @signed_reverse_loop_n_to_lower_limit(
8entry:
9  %tmp5 = icmp eq i32 %n, 0
10  br i1 %tmp5, label %exit, label %loop.preheader
11
12; CHECK:       loop.preheader:
13; CHECK-NEXT:    [[range_start:%.*]] = add i32 %n, -1
14; CHECK-NEXT:    [[first_iteration_check:%.*]] = icmp ult i32 [[range_start]], %length
15; CHECK-NEXT:    [[no_wrap_check:%.*]] = icmp sge i32 %lowerlimit, 1
16; CHECK-NEXT:    [[wide_cond:%.*]] = and i1 [[first_iteration_check]], [[no_wrap_check]]
17loop.preheader:
18  br label %loop
19
20; CHECK: loop:
21; CHECK:    call void (i1, ...) @llvm.experimental.guard(i1 [[wide_cond]], i32 9) [ "deopt"() ]
22loop:
23  %loop.acc = phi i32 [ %loop.acc.next, %loop ], [ 0, %loop.preheader ]
24  %i = phi i32 [ %i.next, %loop ], [ %n, %loop.preheader ]
25  %i.next = add nsw i32 %i, -1
26  %within.bounds = icmp ult i32 %i.next, %length
27  call void (i1, ...) @llvm.experimental.guard(i1 %within.bounds, i32 9) [ "deopt"() ]
28  %i.i64 = zext i32 %i.next to i64
29  %array.i.ptr = getelementptr inbounds i32, i32* %array, i64 %i.i64
30  %array.i = load i32, i32* %array.i.ptr, align 4
31  %loop.acc.next = add i32 %loop.acc, %array.i
32  %continue = icmp sgt i32 %i, %lowerlimit
33  br i1 %continue, label %loop, label %exit
34
35exit:
36  %result = phi i32 [ 0, %entry ], [ %loop.acc.next, %loop ]
37  ret i32 %result
38}
39
40define i32 @unsigned_reverse_loop_n_to_lower_limit(i32* %array, i32 %length, i32 %n, i32 %lowerlimit) {
41; CHECK-LABEL: @unsigned_reverse_loop_n_to_lower_limit(
42entry:
43  %tmp5 = icmp eq i32 %n, 0
44  br i1 %tmp5, label %exit, label %loop.preheader
45
46; CHECK:       loop.preheader:
47; CHECK-NEXT:    [[range_start:%.*]] = add i32 %n, -1
48; CHECK-NEXT:    [[first_iteration_check:%.*]] = icmp ult i32 [[range_start]], %length
49; CHECK-NEXT:    [[no_wrap_check:%.*]] = icmp uge i32 %lowerlimit, 1
50; CHECK-NEXT:    [[wide_cond:%.*]] = and i1 [[first_iteration_check]], [[no_wrap_check]]
51loop.preheader:
52  br label %loop
53
54; CHECK: loop:
55; CHECK:    call void (i1, ...) @llvm.experimental.guard(i1 [[wide_cond]], i32 9) [ "deopt"() ]
56loop:
57  %loop.acc = phi i32 [ %loop.acc.next, %loop ], [ 0, %loop.preheader ]
58  %i = phi i32 [ %i.next, %loop ], [ %n, %loop.preheader ]
59  %i.next = add nsw i32 %i, -1
60  %within.bounds = icmp ult i32 %i.next, %length
61  call void (i1, ...) @llvm.experimental.guard(i1 %within.bounds, i32 9) [ "deopt"() ]
62  %i.i64 = zext i32 %i.next to i64
63  %array.i.ptr = getelementptr inbounds i32, i32* %array, i64 %i.i64
64  %array.i = load i32, i32* %array.i.ptr, align 4
65  %loop.acc.next = add i32 %loop.acc, %array.i
66  %continue = icmp ugt i32 %i, %lowerlimit
67  br i1 %continue, label %loop, label %exit
68
69exit:
70  %result = phi i32 [ 0, %entry ], [ %loop.acc.next, %loop ]
71  ret i32 %result
72}
73
74
75; if we predicated the loop, the guard will definitely fail and we will
76; deoptimize early on.
77define i32 @unsigned_reverse_loop_n_to_0(i32* %array, i32 %length, i32 %n, i32 %lowerlimit) {
78; CHECK-LABEL: @unsigned_reverse_loop_n_to_0(
79entry:
80  %tmp5 = icmp eq i32 %n, 0
81  br i1 %tmp5, label %exit, label %loop.preheader
82
83; CHECK:       loop.preheader:
84; CHECK-NEXT:    [[range_start:%.*]] = add i32 %n, -1
85; CHECK-NEXT:    [[first_iteration_check:%.*]] = icmp ult i32 [[range_start]], %length
86; CHECK-NEXT:    [[wide_cond:%.*]] = and i1 [[first_iteration_check]], false
87loop.preheader:
88  br label %loop
89
90; CHECK: loop:
91; CHECK:    call void (i1, ...) @llvm.experimental.guard(i1 [[wide_cond]], i32 9) [ "deopt"() ]
92loop:
93  %loop.acc = phi i32 [ %loop.acc.next, %loop ], [ 0, %loop.preheader ]
94  %i = phi i32 [ %i.next, %loop ], [ %n, %loop.preheader ]
95  %i.next = add nsw i32 %i, -1
96  %within.bounds = icmp ult i32 %i.next, %length
97  call void (i1, ...) @llvm.experimental.guard(i1 %within.bounds, i32 9) [ "deopt"() ]
98  %i.i64 = zext i32 %i.next to i64
99  %array.i.ptr = getelementptr inbounds i32, i32* %array, i64 %i.i64
100  %array.i = load i32, i32* %array.i.ptr, align 4
101  %loop.acc.next = add i32 %loop.acc, %array.i
102  %continue = icmp ugt i32 %i, 0
103  br i1 %continue, label %loop, label %exit
104
105exit:
106  %result = phi i32 [ 0, %entry ], [ %loop.acc.next, %loop ]
107  ret i32 %result
108}
109
110; do not loop predicate when the range has step -1 and latch has step 1.
111define i32 @reverse_loop_range_step_increment(i32 %n, i32* %array, i32 %length) {
112; CHECK-LABEL: @reverse_loop_range_step_increment(
113entry:
114  %tmp5 = icmp eq i32 %n, 0
115  br i1 %tmp5, label %exit, label %loop.preheader
116
117loop.preheader:
118  br label %loop
119
120; CHECK: loop:
121; CHECK: llvm.experimental.guard(i1 %within.bounds, i32 9)
122loop:
123  %loop.acc = phi i32 [ %loop.acc.next, %loop ], [ 0, %loop.preheader ]
124  %i = phi i32 [ %i.next, %loop ], [ %n, %loop.preheader ]
125  %irc = phi i32 [ %i.inc, %loop ], [ 1, %loop.preheader ]
126  %i.inc = add nuw nsw i32 %irc, 1
127  %within.bounds = icmp ult i32 %irc, %length
128  call void (i1, ...) @llvm.experimental.guard(i1 %within.bounds, i32 9) [ "deopt"() ]
129  %i.i64 = zext i32 %irc to i64
130  %array.i.ptr = getelementptr inbounds i32, i32* %array, i64 %i.i64
131  %array.i = load i32, i32* %array.i.ptr, align 4
132  %i.next = add nsw i32 %i, -1
133  %loop.acc.next = add i32 %loop.acc, %array.i
134  %continue = icmp ugt i32 %i, 65534
135  br i1 %continue, label %loop, label %exit
136
137exit:
138  %result = phi i32 [ 0, %entry ], [ %loop.acc.next, %loop ]
139  ret i32 %result
140}
141