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| ; RUN: opt < %s -loop-unroll -indvars -disable-output
@b = external global i32, align 4
; Test that LoopUnroll does not break LCSSA form.
;
; In this function we have a following CFG:
; ( entry )
; |
; v
; ( outer.header ) <--
; | \
; v |
; --> ( inner.header ) |
; / / \ |
; \ / \ |
; \ v v /
; ( inner.latch ) ( outer.latch )
; |
; v
; ( exit )
;
; When the inner loop is unrolled, we inner.latch block has only one
; predecessor and one successor, so it can be merged with exit block.
; During the merge, however, we remove an LCSSA definition for
; %storemerge1.lcssa, breaking LCSSA form for the outer loop.
; Function Attrs: nounwind uwtable
define void @fn1() #0 {
entry:
br label %outer.header
outer.header: ; preds = %outer.latch, %entry
%storemerge1 = phi i32 [ 0, %entry ], [ %inc9, %outer.latch ]
br label %inner.header
inner.header: ; preds = %inner.latch, %outer.header
%storemerge = phi i32 [ %add, %inner.latch ], [ 0, %outer.header ]
%cmp = icmp slt i32 %storemerge, 1
br i1 %cmp, label %inner.latch, label %outer.latch
inner.latch: ; preds = %inner.header
%tobool4 = icmp eq i32 %storemerge, 0
%add = add nsw i32 %storemerge, 1
br i1 %tobool4, label %inner.header, label %exit
exit: ; preds = %inner.latch
%storemerge1.lcssa = phi i32 [ %storemerge1, %inner.latch ]
store i32 %storemerge1.lcssa, i32* @b, align 4
ret void
outer.latch: ; preds = %inner.header
%inc9 = add nsw i32 %storemerge1, 1
br label %outer.header
}
; This case is similar to the previous one, and has the same CFG.
; The difference is that loop unrolling doesn't remove any LCSSA definition,
; yet breaks LCSSA form for the outer loop. It happens because before unrolling
; block inner.latch was inside outer loop (and consequently, didn't require
; LCSSA definition for %x), but after unrolling it occurs out of the outer
; loop, so we need to insert an LCSSA definition to keep LCSSA.
; Function Attrs: nounwind uwtable
define void @fn2() {
entry:
br label %outer.header
outer.header:
br label %inner.header
inner.header:
%x = load i32, i32* undef, align 4
br i1 true, label %outer.latch, label %inner.latch
inner.latch:
%inc6 = add nsw i32 %x, 1
store i32 %inc6, i32* undef, align 4
br i1 false, label %inner.header, label %exit
exit:
ret void
outer.latch:
br label %outer.header
}
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