1; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py 2; RUN: opt < %s -analyze -enable-new-pm=0 -scalar-evolution | FileCheck %s 3; RUN: opt < %s -disable-output "-passes=print<scalar-evolution>" 2>&1 | FileCheck %s 4 5; Tests demonstrate the bug reported as PR48225 by Congzhe Cao. 6 7; When %boolcond = false and %cond = 0: 8; - %cond.false.on.first.iter is false on 1st iteration; 9; - %cond.false.on.second.iter is false on 2nd iteration; 10; - Therefore, their AND is false on first two iterations, and the backedge is taken twice. 11; 'max backedge-taken count is 1' is a bug caused by wrong treatment of AND 12; condition in the computation logic. It should be 2. 13define void @test_and(i1 %boolcond) { 14; CHECK-LABEL: 'test_and' 15; CHECK-NEXT: Classifying expressions for: @test_and 16; CHECK-NEXT: %conv = zext i1 %boolcond to i32 17; CHECK-NEXT: --> (zext i1 %boolcond to i32) U: [0,2) S: [0,2) 18; CHECK-NEXT: %iv = phi i32 [ 0, %entry ], [ %inc, %backedge ] 19; CHECK-NEXT: --> {0,+,1}<nuw><nsw><%loop> U: [0,3) S: [0,3) Exits: <<Unknown>> LoopDispositions: { %loop: Computable } 20; CHECK-NEXT: %or.cond = and i1 %cond.false.on.first.iter, %cond.false.on.second.iter 21; CHECK-NEXT: --> %or.cond U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Variant } 22; CHECK-NEXT: %inc = add nuw nsw i32 %iv, 1 23; CHECK-NEXT: --> {1,+,1}<nuw><nsw><%loop> U: [1,4) S: [1,4) Exits: <<Unknown>> LoopDispositions: { %loop: Computable } 24; CHECK-NEXT: Determining loop execution counts for: @test_and 25; CHECK-NEXT: Loop %loop: <multiple exits> Unpredictable backedge-taken count. 26; CHECK-NEXT: exit count for loop: 2 27; CHECK-NEXT: exit count for backedge: ***COULDNOTCOMPUTE*** 28; CHECK-NEXT: Loop %loop: max backedge-taken count is 2 29; CHECK-NEXT: Loop %loop: Unpredictable predicated backedge-taken count. 30; 31entry: 32 %conv = zext i1 %boolcond to i32 33 br label %loop 34 35loop: 36 %iv = phi i32 [ 0, %entry ], [ %inc, %backedge ] 37 %cmp = icmp ult i32 %iv, 2 38 br i1 %cmp, label %backedge, label %for.end 39 40backedge: 41 %cond.false.on.first.iter = icmp ne i32 %iv, 0 42 %cond.false.on.second.iter = icmp eq i32 %iv, %conv 43 %or.cond = and i1 %cond.false.on.first.iter, %cond.false.on.second.iter 44 %inc = add nuw nsw i32 %iv, 1 45 br i1 %or.cond, label %exit, label %loop 46 47exit: 48 unreachable 49 50for.end: 51 ret void 52} 53 54; When %boolcond = false and %cond = 0: 55; - %cond.true.on.first.iter is true on 1st iteration; 56; - %cond.true.on.second.iter is true on 2nd iteration; 57; - Therefore, their OR is true on first two iterations, and the backedge is taken twice. 58; 'max backedge-taken count is 1' is a bug caused by wrong treatment of OR 59; condition in the computation logic. It should be 2. 60define void @test_or(i1 %boolcond) { 61; CHECK-LABEL: 'test_or' 62; CHECK-NEXT: Classifying expressions for: @test_or 63; CHECK-NEXT: %conv = zext i1 %boolcond to i32 64; CHECK-NEXT: --> (zext i1 %boolcond to i32) U: [0,2) S: [0,2) 65; CHECK-NEXT: %iv = phi i32 [ 0, %entry ], [ %inc, %backedge ] 66; CHECK-NEXT: --> {0,+,1}<nuw><nsw><%loop> U: [0,3) S: [0,3) Exits: <<Unknown>> LoopDispositions: { %loop: Computable } 67; CHECK-NEXT: %or.cond = or i1 %cond.true.on.first.iter, %cond.true.on.second.iter 68; CHECK-NEXT: --> %or.cond U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Variant } 69; CHECK-NEXT: %inc = add nuw nsw i32 %iv, 1 70; CHECK-NEXT: --> {1,+,1}<nuw><nsw><%loop> U: [1,4) S: [1,4) Exits: <<Unknown>> LoopDispositions: { %loop: Computable } 71; CHECK-NEXT: Determining loop execution counts for: @test_or 72; CHECK-NEXT: Loop %loop: <multiple exits> Unpredictable backedge-taken count. 73; CHECK-NEXT: exit count for loop: 2 74; CHECK-NEXT: exit count for backedge: ***COULDNOTCOMPUTE*** 75; CHECK-NEXT: Loop %loop: max backedge-taken count is 2 76; CHECK-NEXT: Loop %loop: Unpredictable predicated backedge-taken count. 77; 78entry: 79 %conv = zext i1 %boolcond to i32 80 br label %loop 81 82loop: 83 %iv = phi i32 [ 0, %entry ], [ %inc, %backedge ] 84 %cmp = icmp ult i32 %iv, 2 85 br i1 %cmp, label %backedge, label %for.end 86 87backedge: 88 %cond.true.on.first.iter = icmp eq i32 %iv, 0 89 %cond.true.on.second.iter = icmp ne i32 %iv, %conv 90 %or.cond = or i1 %cond.true.on.first.iter, %cond.true.on.second.iter 91 %inc = add nuw nsw i32 %iv, 1 92 br i1 %or.cond, label %loop, label %exit 93 94exit: 95 unreachable 96 97for.end: 98 ret void 99} 100