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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
76 lines
2.0 KiB
LLVM
76 lines
2.0 KiB
LLVM
; RUN: opt < %s -tailcallelim -verify-dom-info -S | FileCheck %s
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; RUN: opt < %s -passes=tailcallelim -verify-dom-info -S | FileCheck %s
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define i32 @test1_factorial(i32 %x) {
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entry:
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%tmp.1 = icmp sgt i32 %x, 0 ; <i1> [#uses=1]
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br i1 %tmp.1, label %then, label %else
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then: ; preds = %entry
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%tmp.6 = add i32 %x, -1 ; <i32> [#uses=1]
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%tmp.4 = call i32 @test1_factorial( i32 %tmp.6 ) ; <i32> [#uses=1]
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%tmp.7 = mul i32 %tmp.4, %x ; <i32> [#uses=1]
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ret i32 %tmp.7
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else: ; preds = %entry
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ret i32 1
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}
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; CHECK-LABEL: define i32 @test1_factorial(
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; CHECK: phi i32
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; CHECK-NOT: call i32
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; CHECK: else:
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; This is a more aggressive form of accumulator recursion insertion, which
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; requires noticing that X doesn't change as we perform the tailcall.
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define i32 @test2_mul(i32 %x, i32 %y) {
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entry:
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%tmp.1 = icmp eq i32 %y, 0 ; <i1> [#uses=1]
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br i1 %tmp.1, label %return, label %endif
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endif: ; preds = %entry
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%tmp.8 = add i32 %y, -1 ; <i32> [#uses=1]
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%tmp.5 = call i32 @test2_mul( i32 %x, i32 %tmp.8 ) ; <i32> [#uses=1]
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%tmp.9 = add i32 %tmp.5, %x ; <i32> [#uses=1]
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ret i32 %tmp.9
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return: ; preds = %entry
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ret i32 %x
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}
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; CHECK-LABEL: define i32 @test2_mul(
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; CHECK: phi i32
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; CHECK-NOT: call i32
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; CHECK: return:
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define i64 @test3_fib(i64 %n) nounwind readnone {
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; CHECK-LABEL: @test3_fib(
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entry:
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; CHECK: tailrecurse:
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; CHECK: %accumulator.tr = phi i64 [ %n, %entry ], [ %3, %bb1 ]
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; CHECK: %n.tr = phi i64 [ %n, %entry ], [ %2, %bb1 ]
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switch i64 %n, label %bb1 [
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; CHECK: switch i64 %n.tr, label %bb1 [
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i64 0, label %bb2
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i64 1, label %bb2
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]
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bb1:
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; CHECK: bb1:
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%0 = add i64 %n, -1
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; CHECK: %0 = add i64 %n.tr, -1
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%1 = tail call i64 @test3_fib(i64 %0) nounwind
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; CHECK: %1 = tail call i64 @test3_fib(i64 %0)
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%2 = add i64 %n, -2
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; CHECK: %2 = add i64 %n.tr, -2
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%3 = tail call i64 @test3_fib(i64 %2) nounwind
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; CHECK-NOT: tail call i64 @test3_fib
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%4 = add nsw i64 %3, %1
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; CHECK: add nsw i64 %accumulator.tr, %1
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ret i64 %4
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; CHECK: br label %tailrecurse
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bb2:
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; CHECK: bb2:
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ret i64 %n
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; CHECK: ret i64 %accumulator.tr
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}
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