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28625d59d9
Summary: Previously, in the NewPM pipeline, TailCallElim recalculates the DomTree when it modifies any instruction in the Function. For example, ``` CallInst *CI = dyn_cast<CallInst>(&I); ... CI->setTailCall(); Modified = true; ... if (!Modified || ...) return PreservedAnalyses::all(); ``` After applying this patch, the DomTree only recalculates if needed (plus an extra insertEdge() + an extra deleteEdge() call). When optimizing SQLite with `-passes="default<O3>"` pipeline of the newPM, the number of DomTree recalculation decreases by 6.2%, the number of nodes visited by DFS decreases by 2.9%. The time used by DomTree will decrease approximately 1%~2.5% after applying the patch. Statistics: ``` Before the patch: 23010 dom-tree-stats - Number of DomTree recalculations 489264 dom-tree-stats - Number of nodes visited by DFS -- DomTree After the patch: 21581 dom-tree-stats - Number of DomTree recalculations 475088 dom-tree-stats - Number of nodes visited by DFS -- DomTree ``` Reviewers: kuhar, dmgreen, brzycki, grosser, davide Reviewed By: kuhar, brzycki Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D49982 llvm-svn: 338954
30 lines
564 B
LLVM
30 lines
564 B
LLVM
; RUN: opt < %s -tailcallelim -verify-dom-info -S | FileCheck %s
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; Test that we don't tail call in a functions that calls returns_twice
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; functions.
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declare void @bar()
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; CHECK: foo1
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; CHECK-NOT: tail call void @bar()
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define void @foo1(i32* %x) {
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bb:
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%tmp75 = tail call i32 @setjmp(i32* %x)
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call void @bar()
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ret void
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}
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declare i32 @setjmp(i32*) returns_twice
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; CHECK: foo2
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; CHECK-NOT: tail call void @bar()
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define void @foo2(i32* %x) {
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bb:
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%tmp75 = tail call i32 @zed2(i32* %x)
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call void @bar()
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ret void
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}
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declare i32 @zed2(i32*) returns_twice
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