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[LSR] Add a test case for (another) miscompile in lsr-term-fold

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Derived from an observation by @nikic on D146457.
This commit is contained in:
Philip Reames 2023-03-21 07:45:30 -07:00 committed by Philip Reames
parent faa1043144
commit b7af34c303
1 changed files with 35 additions and 0 deletions
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35
llvm/test/Transforms/LoopStrengthReduce/lsr-term-fold.ll
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@ -70,6 +70,41 @@ for.end: ; preds = %for.body
ret void
}
; In this case, the i8 IVs increment *isn't* nsw. As a result, a N of 0
; is well defined, and thus the post-inc starts at 255.
; FIXME: miscompile
define void @wrap_around(ptr %a, i8 %N) {
; CHECK-LABEL: @wrap_around(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = zext i8 [[N:%.*]] to i64
; CHECK-NEXT: [[TMP1:%.*]] = shl nuw nsw i64 [[TMP0]], 2
; CHECK-NEXT: [[SCEVGEP:%.*]] = getelementptr i8, ptr [[A:%.*]], i64 [[TMP1]]
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[LSR_IV1:%.*]] = phi ptr [ [[UGLYGEP2:%.*]], [[FOR_BODY]] ], [ [[A]], [[ENTRY:%.*]] ]
; CHECK-NEXT: store i8 1, ptr [[LSR_IV1]], align 4
; CHECK-NEXT: [[UGLYGEP2]] = getelementptr i8, ptr [[LSR_IV1]], i64 4
; CHECK-NEXT: [[LSR_FOLD_TERM_COND_REPLACED_TERM_COND:%.*]] = icmp eq ptr [[UGLYGEP2]], [[SCEVGEP]]
; CHECK-NEXT: br i1 [[LSR_FOLD_TERM_COND_REPLACED_TERM_COND]], label [[FOR_END:%.*]], label [[FOR_BODY]]
; CHECK: for.end:
; CHECK-NEXT: ret void
;
entry:
br label %for.body
for.body: ; preds = %for.body, %entry
%lsr.iv1 = phi ptr [ %uglygep2, %for.body ], [ %a, %entry ]
%lsr.iv = phi i8 [ %lsr.iv.next, %for.body ], [ %N, %entry ]
store i8 1, ptr %lsr.iv1, align 4
%lsr.iv.next = add i8 %lsr.iv, -1
%uglygep2 = getelementptr i8, ptr %lsr.iv1, i64 4
%exitcond.not = icmp eq i8 %lsr.iv.next, 0
br i1 %exitcond.not, label %for.end, label %for.body
for.end: ; preds = %for.body
ret void
}
; The replacing AddRec IV is a complicated AddRec. This tests whether
; the fold terminating condition transformation is writing new terminating
; condition in the correct type.