; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py ; RUN: opt < %s -disable-output "-passes=print<scalar-evolution>" 2>&1 | FileCheck %s ; Tests demonstrate the bug reported as PR48225 by Congzhe Cao. ; When %boolcond = false and %cond = 0: ; - %cond.false.on.first.iter is false on 1st iteration; ; - %cond.false.on.second.iter is false on 2nd iteration; ; - Therefore, their AND is false on first two iterations, and the backedge is taken twice. ; 'max backedge-taken count is 1' is a bug caused by wrong treatment of AND ; condition in the computation logic. It should be 2. define void @test_and(i1 %boolcond) { ; CHECK-LABEL: 'test_and' ; CHECK-NEXT: Classifying expressions for: @test_and ; CHECK-NEXT: %conv = zext i1 %boolcond to i32 ; CHECK-NEXT: --> (zext i1 %boolcond to i32) U: [0,2) S: [0,2) ; CHECK-NEXT: %iv = phi i32 [ 0, %entry ], [ %inc, %backedge ] ; CHECK-NEXT: --> {0,+,1}<nuw><nsw><%loop> U: [0,3) S: [0,3) Exits: <<Unknown>> LoopDispositions: { %loop: Computable } ; CHECK-NEXT: %or.cond = and i1 %cond.false.on.first.iter, %cond.false.on.second.iter ; CHECK-NEXT: --> (%cond.false.on.first.iter umin %cond.false.on.second.iter) U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Variant } ; CHECK-NEXT: %inc = add nuw nsw i32 %iv, 1 ; CHECK-NEXT: --> {1,+,1}<nuw><nsw><%loop> U: [1,4) S: [1,4) Exits: <<Unknown>> LoopDispositions: { %loop: Computable } ; CHECK-NEXT: Determining loop execution counts for: @test_and ; CHECK-NEXT: Loop %loop: <multiple exits> Unpredictable backedge-taken count. ; CHECK-NEXT: exit count for loop: 2 ; CHECK-NEXT: exit count for backedge: ***COULDNOTCOMPUTE*** ; CHECK-NEXT: Loop %loop: max backedge-taken count is 2 ; CHECK-NEXT: Loop %loop: Unpredictable predicated backedge-taken count. ; entry: %conv = zext i1 %boolcond to i32 br label %loop loop: %iv = phi i32 [ 0, %entry ], [ %inc, %backedge ] %cmp = icmp ult i32 %iv, 2 br i1 %cmp, label %backedge, label %for.end backedge: %cond.false.on.first.iter = icmp ne i32 %iv, 0 %cond.false.on.second.iter = icmp eq i32 %iv, %conv %or.cond = and i1 %cond.false.on.first.iter, %cond.false.on.second.iter %inc = add nuw nsw i32 %iv, 1 br i1 %or.cond, label %exit, label %loop exit: unreachable for.end: ret void } ; When %boolcond = false and %cond = 0: ; - %cond.true.on.first.iter is true on 1st iteration; ; - %cond.true.on.second.iter is true on 2nd iteration; ; - Therefore, their OR is true on first two iterations, and the backedge is taken twice. ; 'max backedge-taken count is 1' is a bug caused by wrong treatment of OR ; condition in the computation logic. It should be 2. define void @test_or(i1 %boolcond) { ; CHECK-LABEL: 'test_or' ; CHECK-NEXT: Classifying expressions for: @test_or ; CHECK-NEXT: %conv = zext i1 %boolcond to i32 ; CHECK-NEXT: --> (zext i1 %boolcond to i32) U: [0,2) S: [0,2) ; CHECK-NEXT: %iv = phi i32 [ 0, %entry ], [ %inc, %backedge ] ; CHECK-NEXT: --> {0,+,1}<nuw><nsw><%loop> U: [0,3) S: [0,3) Exits: <<Unknown>> LoopDispositions: { %loop: Computable } ; CHECK-NEXT: %or.cond = or i1 %cond.true.on.first.iter, %cond.true.on.second.iter ; CHECK-NEXT: --> (%cond.true.on.first.iter umax %cond.true.on.second.iter) U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Variant } ; CHECK-NEXT: %inc = add nuw nsw i32 %iv, 1 ; CHECK-NEXT: --> {1,+,1}<nuw><nsw><%loop> U: [1,4) S: [1,4) Exits: <<Unknown>> LoopDispositions: { %loop: Computable } ; CHECK-NEXT: Determining loop execution counts for: @test_or ; CHECK-NEXT: Loop %loop: <multiple exits> Unpredictable backedge-taken count. ; CHECK-NEXT: exit count for loop: 2 ; CHECK-NEXT: exit count for backedge: ***COULDNOTCOMPUTE*** ; CHECK-NEXT: Loop %loop: max backedge-taken count is 2 ; CHECK-NEXT: Loop %loop: Unpredictable predicated backedge-taken count. ; entry: %conv = zext i1 %boolcond to i32 br label %loop loop: %iv = phi i32 [ 0, %entry ], [ %inc, %backedge ] %cmp = icmp ult i32 %iv, 2 br i1 %cmp, label %backedge, label %for.end backedge: %cond.true.on.first.iter = icmp eq i32 %iv, 0 %cond.true.on.second.iter = icmp ne i32 %iv, %conv %or.cond = or i1 %cond.true.on.first.iter, %cond.true.on.second.iter %inc = add nuw nsw i32 %iv, 1 br i1 %or.cond, label %loop, label %exit exit: unreachable for.end: ret void }