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