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llvm-mirror/test/Transforms/LoopDeletion/2017-07-11-incremental-dt.ll
Jakub Kuderski 8f78266b9f [Dominators] Teach LoopDeletion to use the new incremental API
Summary:
This patch makes LoopDeletion use the incremental DominatorTree API.

We modify LoopDeletion to perform the deletion in 5 steps:
1. Create a new dummy edge from the preheader to the exit, by adding a conditional branch.
2. Inform the DomTree about the new edge.
3. Remove the conditional branch and replace it with an unconditional edge to the exit. This removes the edge to the loop header, making it unreachable.
4. Inform the DomTree about the deleted edge.
5. Remove the unreachable block from the function.

Creating the dummy conditional branch is necessary to perform incremental DomTree update.
We should consider using the batch updater when it's ready.

Reviewers: dberlin, davide, grosser, sanjoy

Reviewed By: dberlin, grosser

Subscribers: mzolotukhin, llvm-commits

Differential Revision: https://reviews.llvm.org/D35391

llvm-svn: 309850
2017-08-02 18:17:52 +00:00

57 lines
1.8 KiB
LLVM

; RUN: opt < %s -loop-deletion -S
; RUN: opt < %s -loop-deletion -analyze -domtree 2>&1 | FileCheck -check-prefix=DT %s
; RUN: opt < %s -loop-deletion -analyze -verify-dom-info
; CHECK: for.body
; CHECK-NOT: for.cond1
; Verify only the important parts of the DomTree.
; DT: [1] %entry
; DT: [2] %for.cond
; DT: [3] %lbl63A679E5
; DT: [3] %for.cond9
; DT: [3] %lbl64774A9B
; DT: [3] %for.body
; DT: [4] %for.cond3.loopexit
define i32 @fn1() {
entry:
br label %for.cond
for.cond: ; preds = %entry
br i1 undef, label %lbl63A679E5, label %for.body
for.body: ; preds = %for.cond
br label %for.cond1
for.cond1: ; preds = %for.cond1, %for.body
br i1 undef, label %for.cond1, label %for.cond3.loopexit
for.cond3.loopexit: ; preds = %for.cond1
br label %for.cond3
for.cond3: ; preds = %for.cond9, %for.cond3.loopexit
br i1 undef, label %for.body4, label %for.cond17
for.body4: ; preds = %for.cond3
br label %for.cond5
for.cond5: ; preds = %lbl63A679E5, %for.body4
br label %for.cond9
lbl63A679E5: ; preds = %for.cond
br label %for.cond5
for.cond9: ; preds = %for.end14.split, %for.cond5
br i1 undef, label %for.cond3, label %lbl64774A9B
lbl64774A9B: ; preds = %for.cond17, %for.cond9
br label %for.end14.split
for.end14.split: ; preds = %lbl64774A9B
br label %for.cond9
for.cond17: ; preds = %for.cond3
br label %lbl64774A9B
}