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      1 ; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s
      2 
      3 ; Trip counts with trivial exit conditions.
      4 
      5 ; CHECK: Determining loop execution counts for: @a
      6 ; CHECK: Loop %loop: Unpredictable backedge-taken count.
      7 ; CHECK: Loop %loop: Unpredictable max backedge-taken count.
      8 
      9 ; CHECK: Determining loop execution counts for: @b
     10 ; CHECK: Loop %loop: backedge-taken count is false
     11 ; CHECK: Loop %loop: max backedge-taken count is false
     12 
     13 ; CHECK: Determining loop execution counts for: @c
     14 ; CHECK: Loop %loop: backedge-taken count is false
     15 ; CHECK: Loop %loop: max backedge-taken count is false
     16 
     17 ; CHECK: Determining loop execution counts for: @d
     18 ; CHECK: Loop %loop: Unpredictable backedge-taken count.
     19 ; CHECK: Loop %loop: Unpredictable max backedge-taken count.
     20 
     21 define void @a(i64 %n) nounwind {
     22 entry:
     23   %t0 = icmp sgt i64 %n, 0
     24   br i1 %t0, label %loop, label %return
     25 
     26 loop:
     27   %i = phi i64 [ %i.next, %loop ], [ 0, %entry ]
     28   %i.next = add nsw i64 %i, 1
     29   %exitcond = icmp eq i64 %i.next, %n
     30   br i1 false, label %return, label %loop
     31 
     32 return:
     33   ret void
     34 }
     35 define void @b(i64 %n) nounwind {
     36 entry:
     37   %t0 = icmp sgt i64 %n, 0
     38   br i1 %t0, label %loop, label %return
     39 
     40 loop:
     41   %i = phi i64 [ %i.next, %loop ], [ 0, %entry ]
     42   %i.next = add nsw i64 %i, 1
     43   %exitcond = icmp eq i64 %i.next, %n
     44   br i1 true, label %return, label %loop
     45 
     46 return:
     47   ret void
     48 }
     49 define void @c(i64 %n) nounwind {
     50 entry:
     51   %t0 = icmp sgt i64 %n, 0
     52   br i1 %t0, label %loop, label %return
     53 
     54 loop:
     55   %i = phi i64 [ %i.next, %loop ], [ 0, %entry ]
     56   %i.next = add nsw i64 %i, 1
     57   %exitcond = icmp eq i64 %i.next, %n
     58   br i1 false, label %loop, label %return
     59 
     60 return:
     61   ret void
     62 }
     63 define void @d(i64 %n) nounwind {
     64 entry:
     65   %t0 = icmp sgt i64 %n, 0
     66   br i1 %t0, label %loop, label %return
     67 
     68 loop:
     69   %i = phi i64 [ %i.next, %loop ], [ 0, %entry ]
     70   %i.next = add nsw i64 %i, 1
     71   %exitcond = icmp eq i64 %i.next, %n
     72   br i1 true, label %loop, label %return
     73 
     74 return:
     75   ret void
     76 }
     77 
     78 ; Trip counts for non-polynomial iterations. It's theoretically possible
     79 ; to compute a maximum count for these, but short of that, ScalarEvolution
     80 ; should return unknown.
     81 
     82 ; PR7416
     83 ; CHECK: Determining loop execution counts for: @nonpolynomial
     84 ; CHECK-NEXT: Loop %loophead: Unpredictable backedge-taken count
     85 ; CHECK-NEXT: Loop %loophead: Unpredictable max backedge-taken count
     86 
     87 declare i1 @g() nounwind
     88 
     89 define void @nonpolynomial() {
     90 entry:
     91   br label %loophead
     92 loophead:
     93   %x = phi i32 [0, %entry], [%x.1, %bb1], [%x.2, %bb2]
     94   %y = icmp slt i32 %x, 100
     95   br i1 %y, label %loopbody, label %retbb
     96 loopbody:
     97   %z = call i1 @g()
     98   br i1 %z, label %bb1, label %bb2
     99 bb1:
    100   %x.1 = add i32 %x, 2
    101   br label %loophead
    102 bb2:
    103   %x.2 = add i32 %x, 3
    104   br label %loophead
    105 retbb:
    106   ret void
    107 }
    108 
    109 ; PHI nodes with all constant operands.
    110 
    111 ; CHECK: Determining loop execution counts for: @constant_phi_operands
    112 ; CHECK: Loop %loop: backedge-taken count is 1
    113 ; CHECK: Loop %loop: max backedge-taken count is 1
    114 
    115 define void @constant_phi_operands() nounwind {
    116 entry:
    117   br label %loop
    118 
    119 loop:
    120   %i = phi i64 [ 1, %loop ], [ 0, %entry ]
    121   %exitcond = icmp eq i64 %i, 1
    122   br i1 %exitcond, label %return, label %loop
    123 
    124 return:
    125   ret void
    126 }
    127 
    128 ; PR16130: Loop exit depends on an 'or' expression.
    129 ; One side of the expression test against a value that will be skipped.
    130 ; We can't assume undefined behavior just because we have an NSW flag.
    131 ;
    132 ; CHECK: Determining loop execution counts for: @exit_orcond_nsw
    133 ; CHECK: Loop %for.body.i: Unpredictable backedge-taken count.
    134 ; CHECK: Loop %for.body.i: max backedge-taken count is 1
    135 define void @exit_orcond_nsw(i32 *%a) nounwind {
    136 entry:
    137   br label %for.body.i
    138 
    139 for.body.i:                                       ; preds = %for.body.i, %entry
    140   %b.01.i = phi i32 [ 0, %entry ], [ %add.i, %for.body.i ]
    141   %tobool.i = icmp ne i32 %b.01.i, 0
    142   %add.i = add nsw i32 %b.01.i, 8
    143   %cmp.i = icmp eq i32 %add.i, 13
    144   %or.cond = or i1 %tobool.i, %cmp.i
    145   br i1 %or.cond, label %exit, label %for.body.i
    146 
    147 exit:                                     ; preds = %for.body.i
    148   %b.01.i.lcssa = phi i32 [ %b.01.i, %for.body.i ]
    149   store i32 %b.01.i.lcssa, i32* %a, align 4
    150   ret void
    151 }
    152