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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
39 lines
1.6 KiB
LLVM
39 lines
1.6 KiB
LLVM
; RUN: opt %s -tailcallelim -verify-dom-info -pass-remarks=tailcallelim -o /dev/null 2>&1 | FileCheck %s
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; RUN: opt %s -o /dev/null -passes='require<opt-remark-emit>,tailcallelim' -pass-remarks=tailcallelim 2>&1 | FileCheck %s
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; CHECK: /home/davide/pat.c:2:20: transforming tail recursion into loop
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define i32 @fib(i32 %n) nounwind ssp {
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entry:
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%cmp = icmp slt i32 %n, 2
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br i1 %cmp, label %if.then, label %if.end
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if.then: ; preds = %entry
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br label %return
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if.end: ; preds = %entry
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%sub = add nsw i32 %n, -2
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%call = call i32 @fib(i32 %sub)
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%sub3 = add nsw i32 %n, -1
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%call4 = call i32 @fib(i32 %sub3), !dbg !8
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%add = add nsw i32 %call, %call4
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br label %return
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return: ; preds = %if.end, %if.then
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%retval.0 = phi i32 [ 1, %if.then ], [ %add, %if.end ]
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ret i32 %retval.0
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}
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!3, !4}
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!llvm.ident = !{!5}
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!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 3.9.0 ", isOptimized: true, runtimeVersion: 0, emissionKind: NoDebug, enums: !2)
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!1 = !DIFile(filename: "/home/davide/pat.c", directory: "/tmp")
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!2 = !{}
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!3 = !{i32 2, !"Debug Info Version", i32 3}
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!4 = !{i32 1, !"PIC Level", i32 2}
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!5 = !{!"clang version 3.9.0 "}
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!6 = distinct !DISubprogram(name: "success", scope: !1, file: !1, line: 1, type: !7, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !2)
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!7 = !DISubroutineType(types: !2)
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!8 = !DILocation(line: 2, column: 20, scope: !6)
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