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1; RUN: opt < %s -passes=loop-unroll,indvars -disable-output2 3@b = external global i32, align 44 5; Test that LoopUnroll does not break LCSSA form.6;7; In this function we have a following CFG:8; ( entry )9; |10; v11; ( outer.header ) <--12; | \13; v |14; --> ( inner.header ) |15; / / \ |16; \ / \ |17; \ v v /18; ( inner.latch ) ( outer.latch )19; |20; v21; ( exit )22;23; When the inner loop is unrolled, we inner.latch block has only one24; predecessor and one successor, so it can be merged with exit block.25; During the merge, however, we remove an LCSSA definition for26; %storemerge1.lcssa, breaking LCSSA form for the outer loop.27 28; Function Attrs: nounwind uwtable29define void @fn1() #0 {30entry:31 br label %outer.header32 33outer.header: ; preds = %outer.latch, %entry34 %storemerge1 = phi i32 [ 0, %entry ], [ %inc9, %outer.latch ]35 br label %inner.header36 37inner.header: ; preds = %inner.latch, %outer.header38 %storemerge = phi i32 [ %add, %inner.latch ], [ 0, %outer.header ]39 %cmp = icmp slt i32 %storemerge, 140 br i1 %cmp, label %inner.latch, label %outer.latch41 42inner.latch: ; preds = %inner.header43 %tobool4 = icmp eq i32 %storemerge, 044 %add = add nsw i32 %storemerge, 145 br i1 %tobool4, label %inner.header, label %exit46 47exit: ; preds = %inner.latch48 %storemerge1.lcssa = phi i32 [ %storemerge1, %inner.latch ]49 store i32 %storemerge1.lcssa, ptr @b, align 450 ret void51 52outer.latch: ; preds = %inner.header53 %inc9 = add nsw i32 %storemerge1, 154 br label %outer.header55}56 57; This case is similar to the previous one, and has the same CFG.58; The difference is that loop unrolling doesn't remove any LCSSA definition,59; yet breaks LCSSA form for the outer loop. It happens because before unrolling60; block inner.latch was inside outer loop (and consequently, didn't require61; LCSSA definition for %x), but after unrolling it occurs out of the outer62; loop, so we need to insert an LCSSA definition to keep LCSSA.63 64; Function Attrs: nounwind uwtable65define void @fn2() {66entry:67 br label %outer.header68 69outer.header:70 br label %inner.header71 72inner.header:73 %x = load i32, ptr undef, align 474 br i1 true, label %outer.latch, label %inner.latch75 76inner.latch:77 %inc6 = add nsw i32 %x, 178 store i32 %inc6, ptr undef, align 479 br i1 false, label %inner.header, label %exit80 81exit:82 ret void83 84outer.latch:85 br label %outer.header86}87