diff options
Diffstat (limited to 'test/Transforms/LoopUnroll/pr18861.ll')
| -rw-r--r-- | test/Transforms/LoopUnroll/pr18861.ll | 91 |
1 files changed, 67 insertions, 24 deletions
diff --git a/test/Transforms/LoopUnroll/pr18861.ll b/test/Transforms/LoopUnroll/pr18861.ll index 62f26106afb2..c01eef1d0e5d 100644 --- a/test/Transforms/LoopUnroll/pr18861.ll +++ b/test/Transforms/LoopUnroll/pr18861.ll @@ -2,42 +2,85 @@ @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 %for.cond1thread-pre-split - -for.cond1thread-pre-split: ; preds = %for.inc8, %entry - %storemerge1 = phi i32 [ 0, %entry ], [ %inc9, %for.inc8 ] - br i1 undef, label %for.inc8, label %for.cond2.preheader.lr.ph + br label %outer.header -for.cond2.preheader.lr.ph: ; preds = %for.cond1thread-pre-split - br label %for.cond2.preheader +outer.header: ; preds = %outer.latch, %entry + %storemerge1 = phi i32 [ 0, %entry ], [ %inc9, %outer.latch ] + br label %inner.header -for.cond2.preheader: ; preds = %for.inc5, %for.cond2.preheader.lr.ph - br label %for.cond2 - -for.cond2: ; preds = %for.body3, %for.cond2.preheader - %storemerge = phi i32 [ %add, %for.body3 ], [ 0, %for.cond2.preheader ] +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 %for.body3, label %for.inc5 + br i1 %cmp, label %inner.latch, label %outer.latch -for.body3: ; preds = %for.cond2 +inner.latch: ; preds = %inner.header %tobool4 = icmp eq i32 %storemerge, 0 %add = add nsw i32 %storemerge, 1 - br i1 %tobool4, label %for.cond2, label %if.then + br i1 %tobool4, label %inner.header, label %exit -if.then: ; preds = %for.body3 - store i32 %storemerge1, i32* @b, align 4 +exit: ; preds = %inner.latch + %storemerge1.lcssa = phi i32 [ %storemerge1, %inner.latch ] + store i32 %storemerge1.lcssa, i32* @b, align 4 ret void -for.inc5: ; preds = %for.cond2 - br i1 undef, label %for.cond1.for.inc8_crit_edge, label %for.cond2.preheader +outer.latch: ; preds = %inner.header + %inc9 = add nsw i32 %storemerge1, 1 + br label %outer.header +} -for.cond1.for.inc8_crit_edge: ; preds = %for.inc5 - br label %for.inc8 +; 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. -for.inc8: ; preds = %for.cond1.for.inc8_crit_edge, %for.cond1thread-pre-split - %inc9 = add nsw i32 %storemerge1, 1 - br label %for.cond1thread-pre-split +; 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 } |