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c9b1e25493
The primary advantage is that loop optimizations will be applied in a stable order. This helps debugging and unit test creation. It is also a better overall implementation without pathologically bad performance on deep functions. On large functions (llvm-stress --size=200000 | opt -loops) Before: 0.1263s After: 0.0225s On deep functions (after tweaking llvm-stress, thanks Nadav): Before: 0.2281s After: 0.0227s See r158790 for more comments. The loop tree is now consistently generated in forward order, but loop passes are applied in reverse order over the program. If we have a loop optimization that prefers forward order, that can easily be achieved by adding a different type of LoopPassManager. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159183 91177308-0d34-0410-b5e6-96231b3b80d8
139 lines
5.5 KiB
LLVM
139 lines
5.5 KiB
LLVM
; RUN: opt -loop-unswitch -loop-unswitch-threshold 1000 -disable-output -stats -info-output-file - < %s | FileCheck --check-prefix=STATS %s
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; RUN: opt -S -loop-unswitch -loop-unswitch-threshold 1000 -verify-loop-info -verify-dom-info %s | FileCheck %s
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; STATS: 1 loop-simplify - Number of pre-header or exit blocks inserted
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; STATS: 3 loop-unswitch - Number of switches unswitched
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; CHECK: %1 = icmp eq i32 %c, 1
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; CHECK-NEXT: br i1 %1, label %.split.us, label %..split_crit_edge
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; CHECK: ..split_crit_edge: ; preds = %0
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; CHECK-NEXT: br label %.split
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; CHECK: .split.us: ; preds = %0
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; CHECK-NEXT: %2 = icmp eq i32 %d, 1
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; CHECK-NEXT: br i1 %2, label %.split.us.split.us, label %.split.us..split.us.split_crit_edge
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; CHECK: .split.us..split.us.split_crit_edge: ; preds = %.split.us
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; CHECK-NEXT: br label %.split.us.split
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; CHECK: .split.us.split.us: ; preds = %.split.us
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; CHECK-NEXT: br label %loop_begin.us.us
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; CHECK: loop_begin.us.us: ; preds = %loop_begin.backedge.us.us, %.split.us.split.us
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; CHECK-NEXT: %var_val.us.us = load i32* %var
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; CHECK-NEXT: switch i32 1, label %second_switch.us.us [
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; CHECK-NEXT: i32 1, label %inc.us.us
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; CHECK: second_switch.us.us: ; preds = %loop_begin.us.us
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; CHECK-NEXT: switch i32 1, label %default.us.us [
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; CHECK-NEXT: i32 1, label %inc.us.us
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; CHECK: inc.us.us: ; preds = %second_switch.us.us, %loop_begin.us.us
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; CHECK-NEXT: call void @incf() noreturn nounwind
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; CHECK-NEXT: br label %loop_begin.backedge.us.us
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; CHECK: .split.us.split: ; preds = %.split.us..split.us.split_crit_edge
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; CHECK-NEXT: br label %loop_begin.us
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; CHECK: loop_begin.us: ; preds = %loop_begin.backedge.us, %.split.us.split
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; CHECK-NEXT: %var_val.us = load i32* %var
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; CHECK-NEXT: switch i32 1, label %second_switch.us [
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; CHECK-NEXT: i32 1, label %inc.us
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; CHECK: second_switch.us: ; preds = %loop_begin.us
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; CHECK-NEXT: switch i32 %d, label %default.us [
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; CHECK-NEXT: i32 1, label %second_switch.us.inc.us_crit_edge
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; CHECK-NEXT: ]
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; CHECK: second_switch.us.inc.us_crit_edge: ; preds = %second_switch.us
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; CHECK-NEXT: br i1 true, label %us-unreachable8, label %inc.us
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; CHECK: inc.us: ; preds = %second_switch.us.inc.us_crit_edge, %loop_begin.us
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; CHECK-NEXT: call void @incf() noreturn nounwind
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; CHECK-NEXT: br label %loop_begin.backedge.us
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; CHECK: .split: ; preds = %..split_crit_edge
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; CHECK-NEXT: %3 = icmp eq i32 %d, 1
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; CHECK-NEXT: br i1 %3, label %.split.split.us, label %.split..split.split_crit_edge
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; CHECK: .split..split.split_crit_edge: ; preds = %.split
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; CHECK-NEXT: br label %.split.split
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; CHECK: .split.split.us: ; preds = %.split
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; CHECK-NEXT: br label %loop_begin.us1
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; CHECK: loop_begin.us1: ; preds = %loop_begin.backedge.us6, %.split.split.us
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; CHECK-NEXT: %var_val.us2 = load i32* %var
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; CHECK-NEXT: switch i32 %c, label %second_switch.us3 [
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; CHECK-NEXT: i32 1, label %loop_begin.inc_crit_edge.us
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; CHECK-NEXT: ]
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; CHECK: second_switch.us3: ; preds = %loop_begin.us1
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; CHECK-NEXT: switch i32 1, label %default.us5 [
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; CHECK-NEXT: i32 1, label %inc.us4
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; CHECK-NEXT: ]
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; CHECK: inc.us4: ; preds = %loop_begin.inc_crit_edge.us, %second_switch.us3
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; CHECK-NEXT: call void @incf() noreturn nounwind
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; CHECK-NEXT: br label %loop_begin.backedge.us6
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; CHECK: loop_begin.inc_crit_edge.us: ; preds = %loop_begin.us1
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; CHECK-NEXT: br i1 true, label %us-unreachable.us-lcssa.us, label %inc.us4
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; CHECK: .split.split: ; preds = %.split..split.split_crit_edge
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; CHECK-NEXT: br label %loop_begin
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; CHECK: loop_begin: ; preds = %loop_begin.backedge, %.split.split
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; CHECK-NEXT: %var_val = load i32* %var
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; CHECK-NEXT: switch i32 %c, label %second_switch [
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; CHECK-NEXT: i32 1, label %loop_begin.inc_crit_edge
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; CHECK-NEXT: ]
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; CHECK: loop_begin.inc_crit_edge: ; preds = %loop_begin
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; CHECK-NEXT: br i1 true, label %us-unreachable.us-lcssa, label %inc
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; CHECK: second_switch: ; preds = %loop_begin
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; CHECK-NEXT: switch i32 %d, label %default [
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; CHECK-NEXT: i32 1, label %second_switch.inc_crit_edge
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; CHECK-NEXT: ]
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; CHECK: second_switch.inc_crit_edge: ; preds = %second_switch
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; CHECK-NEXT: br i1 true, label %us-unreachable7, label %inc
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define i32 @test(i32* %var) {
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%mem = alloca i32
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store i32 2, i32* %mem
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%c = load i32* %mem
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%d = load i32* %mem
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br label %loop_begin
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loop_begin:
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%var_val = load i32* %var
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switch i32 %c, label %second_switch [
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i32 1, label %inc
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]
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second_switch:
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switch i32 %d, label %default [
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i32 1, label %inc
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]
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inc:
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call void @incf() noreturn nounwind
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br label %loop_begin
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default:
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br label %loop_begin
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loop_exit:
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ret i32 0
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}
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declare void @incf() noreturn
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declare void @decf() noreturn
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