8b5de48d62
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
175 lines
5.3 KiB
LLVM
175 lines
5.3 KiB
LLVM
; RUN: opt < %s -tailcallelim -verify-dom-info -S | FileCheck %s
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; PR4323
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target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
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; Several cases where tail call elimination should move the load above the call,
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; then eliminate the tail recursion.
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@global = external global i32 ; <i32*> [#uses=1]
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@extern_weak_global = extern_weak global i32 ; <i32*> [#uses=1]
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; This load can be moved above the call because the function won't write to it
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; and the call has no side effects.
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define fastcc i32 @raise_load_1(i32* %a_arg, i32 %a_len_arg, i32 %start_arg) nounwind readonly {
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; CHECK-LABEL: @raise_load_1(
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; CHECK-NOT: call
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; CHECK: load i32, i32*
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; CHECK-NOT: call
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; CHECK: }
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entry:
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%tmp2 = icmp sge i32 %start_arg, %a_len_arg ; <i1> [#uses=1]
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br i1 %tmp2, label %if, label %else
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if: ; preds = %entry
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ret i32 0
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else: ; preds = %entry
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%tmp7 = add i32 %start_arg, 1 ; <i32> [#uses=1]
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%tmp8 = call fastcc i32 @raise_load_1(i32* %a_arg, i32 %a_len_arg, i32 %tmp7) ; <i32> [#uses=1]
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%tmp9 = load i32, i32* %a_arg ; <i32> [#uses=1]
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%tmp10 = add i32 %tmp9, %tmp8 ; <i32> [#uses=1]
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ret i32 %tmp10
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}
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; This load can be moved above the call because the function won't write to it
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; and the load provably can't trap.
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define fastcc i32 @raise_load_2(i32* %a_arg, i32 %a_len_arg, i32 %start_arg) readonly {
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; CHECK-LABEL: @raise_load_2(
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; CHECK-NOT: call
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; CHECK: load i32, i32*
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; CHECK-NOT: call
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; CHECK: }
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entry:
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%tmp2 = icmp sge i32 %start_arg, %a_len_arg ; <i1> [#uses=1]
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br i1 %tmp2, label %if, label %else
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if: ; preds = %entry
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ret i32 0
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else: ; preds = %entry
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%nullcheck = icmp eq i32* %a_arg, null ; <i1> [#uses=1]
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br i1 %nullcheck, label %unwind, label %recurse
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unwind: ; preds = %else
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unreachable
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recurse: ; preds = %else
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%tmp7 = add i32 %start_arg, 1 ; <i32> [#uses=1]
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%tmp8 = call fastcc i32 @raise_load_2(i32* %a_arg, i32 %a_len_arg, i32 %tmp7) ; <i32> [#uses=1]
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%tmp9 = load i32, i32* @global ; <i32> [#uses=1]
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%tmp10 = add i32 %tmp9, %tmp8 ; <i32> [#uses=1]
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ret i32 %tmp10
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}
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; This load can be safely moved above the call (even though it's from an
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; extern_weak global) because the call has no side effects.
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define fastcc i32 @raise_load_3(i32* %a_arg, i32 %a_len_arg, i32 %start_arg) nounwind readonly {
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; CHECK-LABEL: @raise_load_3(
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; CHECK-NOT: call
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; CHECK: load i32, i32*
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; CHECK-NOT: call
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; CHECK: }
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entry:
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%tmp2 = icmp sge i32 %start_arg, %a_len_arg ; <i1> [#uses=1]
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br i1 %tmp2, label %if, label %else
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if: ; preds = %entry
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ret i32 0
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else: ; preds = %entry
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%tmp7 = add i32 %start_arg, 1 ; <i32> [#uses=1]
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%tmp8 = call fastcc i32 @raise_load_3(i32* %a_arg, i32 %a_len_arg, i32 %tmp7) ; <i32> [#uses=1]
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%tmp9 = load i32, i32* @extern_weak_global ; <i32> [#uses=1]
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%tmp10 = add i32 %tmp9, %tmp8 ; <i32> [#uses=1]
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ret i32 %tmp10
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}
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; The second load can be safely moved above the call even though it's from an
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; unknown pointer (which normally means it might trap) because the first load
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; proves it doesn't trap.
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define fastcc i32 @raise_load_4(i32* %a_arg, i32 %a_len_arg, i32 %start_arg) readonly {
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; CHECK-LABEL: @raise_load_4(
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; CHECK-NOT: call
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; CHECK: load i32, i32*
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; CHECK-NEXT: load i32, i32*
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; CHECK-NOT: call
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; CHECK: }
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entry:
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%tmp2 = icmp sge i32 %start_arg, %a_len_arg ; <i1> [#uses=1]
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br i1 %tmp2, label %if, label %else
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if: ; preds = %entry
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ret i32 0
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else: ; preds = %entry
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%nullcheck = icmp eq i32* %a_arg, null ; <i1> [#uses=1]
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br i1 %nullcheck, label %unwind, label %recurse
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unwind: ; preds = %else
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unreachable
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recurse: ; preds = %else
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%tmp7 = add i32 %start_arg, 1 ; <i32> [#uses=1]
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%first = load i32, i32* %a_arg ; <i32> [#uses=1]
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%tmp8 = call fastcc i32 @raise_load_4(i32* %a_arg, i32 %first, i32 %tmp7) ; <i32> [#uses=1]
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%second = load i32, i32* %a_arg ; <i32> [#uses=1]
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%tmp10 = add i32 %second, %tmp8 ; <i32> [#uses=1]
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ret i32 %tmp10
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}
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; This load can be moved above the call because the function won't write to it
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; and the a_arg is dereferenceable.
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define fastcc i32 @raise_load_5(i32* dereferenceable(4) %a_arg, i32 %a_len_arg, i32 %start_arg) readonly {
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; CHECK-LABEL: @raise_load_5(
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; CHECK-NOT: call
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; CHECK: load i32, i32*
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; CHECK-NOT: call
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; CHECK: }
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entry:
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%tmp2 = icmp sge i32 %start_arg, %a_len_arg ; <i1> [#uses=1]
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br i1 %tmp2, label %if, label %else
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if: ; preds = %entry
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ret i32 0
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else: ; preds = %entry
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%tmp7 = add i32 %start_arg, 1 ; <i32> [#uses=1]
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%tmp8 = call fastcc i32 @raise_load_5(i32* %a_arg, i32 %a_len_arg, i32 %tmp7) ; <i32> [#uses=1]
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%tmp9 = load i32, i32* %a_arg ; <i32> [#uses=1]
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%tmp10 = add i32 %tmp9, %tmp8 ; <i32> [#uses=1]
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ret i32 %tmp10
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}
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; This load can be moved above the call because the function call does not write to the memory the load
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; is accessing and the load is safe to speculate.
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define fastcc i32 @raise_load_6(i32* %a_arg, i32 %a_len_arg, i32 %start_arg) nounwind {
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; CHECK-LABEL: @raise_load_6(
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; CHECK-NOT: call
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; CHECK: load i32, i32*
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; CHECK-NOT: call
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; CHECK: }
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entry:
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%s = alloca i32
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store i32 4, i32* %s
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%tmp2 = icmp sge i32 %start_arg, %a_len_arg ; <i1> [#uses=1]
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br i1 %tmp2, label %if, label %else
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if: ; preds = %entry
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store i32 1, i32* %a_arg
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ret i32 0
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else: ; preds = %entry
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%tmp7 = add i32 %start_arg, 1 ; <i32> [#uses=1]
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%tmp8 = call fastcc i32 @raise_load_6(i32* %a_arg, i32 %a_len_arg, i32 %tmp7) ; <i32> [#uses=1]
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%tmp9 = load i32, i32* %s ; <i32> [#uses=1]
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%tmp10 = add i32 %tmp9, %tmp8 ; <i32> [#uses=1]
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ret i32 %tmp10
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}
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