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[SCEV] Add test cases where the max BTC is imprecise, due to step != 1. 

Add a test case where we fail to compute a tight max backedge taken
count, due to the step being != 1.

This is part of the issue with PR40961.
This commit is contained in:
Florian Hahn 2020-10-10 16:39:48 +01:00
parent 2e9fd754b4
commit d48b249b71
1 changed files with 22 additions and 0 deletions
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22
llvm/test/Analysis/ScalarEvolution/max-backedge-taken-count-guard-info.ll
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@ -135,6 +135,28 @@ exit:
ret void
}
define void @test_guard_ule_12_step2(i32* nocapture %a, i64 %N) {
; CHECK-LABEL: Determining loop execution counts for: @test_guard_ule_12_step2
; CHECK-NEXT: Loop %loop: backedge-taken count is (%N /u 2)
; CHECK-NEXT: Loop %loop: max backedge-taken count is 9223372036854775807
; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is (%N /u 2)
;
entry:
%c.1 = icmp ule i64 %N, 12
br i1 %c.1, label %loop, label %exit
loop:
%iv = phi i64 [ %iv.next, %loop ], [ 0, %entry ]
%idx = getelementptr inbounds i32, i32* %a, i64 %iv
store i32 1, i32* %idx, align 4
%iv.next = add nuw nsw i64 %iv, 2
%exitcond = icmp eq i64 %iv, %N
br i1 %exitcond, label %exit, label %loop
exit:
ret void
}
define void @test_multiple_const_guards_order1(i32* nocapture %a, i64 %i) {
; CHECK-LABEL: @test_multiple_const_guards_order1
; CHECK: Loop %loop: backedge-taken count is %i