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SCEV: cover a codepath in isImpliedCondBalancedTypes (#123070)

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The code that checks a predicate against a swapped predicate in
isImpliedCondBalancedTypes is not covered by any existing test, within
any Analysis or Transform. Fix this by adding a test to SCEV.
This commit is contained in:
Ramkumar Ramachandra 2025-01-23 12:28:30 +00:00 committed by GitHub
parent 9705500582
commit e069518f82
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1 changed files with 53 additions and 0 deletions
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53
llvm/test/Analysis/ScalarEvolution/implied-via-division.ll
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@ -411,3 +411,56 @@ header:
exit:
ret void
}
define void @swapped_predicate(i32 %n) {
; Prove that (n s>= 1) ===> (0 s>= -n / 2).
; CHECK-LABEL: 'swapped_predicate'
; CHECK-NEXT: Determining loop execution counts for: @swapped_predicate
; CHECK-NEXT: Loop %header: backedge-taken count is (1 + %n.div.2)<nuw><nsw>
; CHECK-NEXT: Loop %header: constant max backedge-taken count is i32 1073741824
; CHECK-NEXT: Loop %header: symbolic max backedge-taken count is (1 + %n.div.2)<nuw><nsw>
; CHECK-NEXT: Loop %header: Trip multiple is 1
;
entry:
%cmp1 = icmp sge i32 %n, 1
%n.div.2 = sdiv i32 %n, 2
call void @llvm.assume(i1 %cmp1)
br label %header
header:
%indvar = phi i32 [ %indvar.next, %header ], [ 0, %entry ]
%indvar.next = add i32 %indvar, 1
%minus.indvar = sub nsw i32 0, %indvar
%minus.n.div.2 = sub nsw i32 0, %n.div.2
%exitcond = icmp sge i32 %minus.indvar, %minus.n.div.2
br i1 %exitcond, label %header, label %exit
exit:
ret void
}
define void @swapped_predicate_neg(i32 %n) {
; Prove that (n s>= 1) =\=> (-n / 2 s>= 0).
; CHECK-LABEL: 'swapped_predicate_neg'
; CHECK-NEXT: Determining loop execution counts for: @swapped_predicate_neg
; CHECK-NEXT: Loop %header: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %header: Unpredictable constant max backedge-taken count.
; CHECK-NEXT: Loop %header: Unpredictable symbolic max backedge-taken count.
;
entry:
%cmp1 = icmp sge i32 %n, 1
%n.div.2 = sdiv i32 %n, 2
call void @llvm.assume(i1 %cmp1)
br label %header
header:
%indvar = phi i32 [ %indvar.next, %header ], [ 0, %entry ]
%indvar.next = add i32 %indvar, 1
%minus.indvar = sub nsw i32 0, %indvar
%minus.n.div.2 = sub nsw i32 0, %n.div.2
%exitcond = icmp sge i32 %minus.n.div.2, %minus.indvar
br i1 %exitcond, label %header, label %exit
exit:
ret void
}