1; RUN: opt < %s -S -unroll-runtime -unroll-count=2 -loop-unroll -unroll-runtime-epilog=true  | FileCheck %s -check-prefix=EPILOG
2; RUN: opt < %s -S -unroll-runtime -unroll-count=2 -loop-unroll -unroll-runtime-epilog=false | FileCheck %s -check-prefix=PROLOG
3target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
4
5; This test case documents how runtime loop unrolling handles the case
6; when the backedge-count is -1.
7
8; If %N, the backedge-taken count, is -1 then %0 unsigned-overflows
9; and is 0.  %xtraiter too is 0, signifying that the total trip-count
10; is divisible by 2.  The prologue then branches to the unrolled loop
11; and executes the 2^32 iterations there, in groups of 2.
12
13; EPILOG: entry:
14
15; EPILOG-NEXT: %0 = add i32 %N, 1
16; EPILOG-NEXT: %xtraiter = and i32 %0, 1
17; EPILOG-NEXT: %1 = icmp ult i32 %N, 1
18; EPILOG-NEXT: br i1 %1, label %while.end.unr-lcssa, label %entry.new
19; EPILOG: while.body:
20
21; EPILOG: %lcmp.mod = icmp ne i32 %xtraiter, 0
22; EPILOG-NEXT: br i1 %lcmp.mod, label %while.body.epil.preheader, label %while.end
23; EPILOG: while.body.epil:
24
25; PROLOG: entry:
26; PROLOG-NEXT: %0 = add i32 %N, 1
27; PROLOG-NEXT: %xtraiter = and i32 %0, 1
28; PROLOG-NEXT: %lcmp.mod = icmp ne i32 %xtraiter, 0
29; PROLOG-NEXT: br i1 %lcmp.mod, label %while.body.prol.preheader, label %while.body.prol.loopexit
30; PROLOG: while.body.prol:
31
32; PROLOG: %1 = icmp ult i32 %N, 1
33; PROLOG-NEXT: br i1 %1, label %while.end, label %entry.new
34; PROLOG: while.body:
35
36; Function Attrs: nounwind readnone ssp uwtable
37define i32 @foo(i32 %N) {
38entry:
39  br label %while.body
40
41while.body:                                       ; preds = %while.body, %entry
42  %i = phi i32 [ 0, %entry ], [ %inc, %while.body ]
43  %cmp = icmp eq i32 %i, %N
44  %inc = add i32 %i, 1
45  br i1 %cmp, label %while.end, label %while.body
46
47while.end:                                        ; preds = %while.body
48  ret i32 %i
49}
50