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3d72b70842
The first variant contains all current transformations except transforming switches into lookup tables. The second variant contains all current transformations. The switch-to-lookup-table conversion results in code that is more difficult to analyze and optimize by other passes. Most importantly, it can inhibit Dead Code Elimination. As such it is often beneficial to only apply this transformation very late. A common example is inlining, which can often result in range restrictions for the switch expression. Changes in execution time according to LNT: SingleSource/Benchmarks/Misc/fp-convert +3.03% MultiSource/Benchmarks/ASC_Sequoia/CrystalMk/CrystalMk -11.20% MultiSource/Benchmarks/Olden/perimeter/perimeter -10.43% and a couple of smaller changes. For perimeter it also results 2.6% a smaller binary. Differential Revision: https://reviews.llvm.org/D30333 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@298799 91177308-0d34-0410-b5e6-96231b3b80d8
49 lines
1.5 KiB
LLVM
49 lines
1.5 KiB
LLVM
; RUN: opt -latesimplifycfg -S %s | FileCheck %s
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; rdar://15268442
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target datalayout = "e-p:64:64:64-S128-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f16:16:16-f32:32:32-f64:64:64-f128:128:128-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
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target triple = "x86_64-apple-darwin12.0.0"
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; CHECK-LABEL: define i3 @coveredswitch_test(
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; CHECK: entry:
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; CHECK-NEXT: sub i3 %input, -4
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; CHECK-NEXT: zext i3 %switch.tableidx to i24
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; CHECK-NEXT: mul i24 %switch.cast, 3
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; CHECK-NEXT: lshr i24 7507338, %switch.shiftamt
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; CHECK-NEXT: trunc i24 %switch.downshift to i3
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; CHECK-NEXT: ret i3 %switch.masked
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define i3 @coveredswitch_test(i3 %input) {
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entry:
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switch i3 %input, label %bb8 [
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i3 0, label %bb7
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i3 1, label %bb
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i3 2, label %bb3
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i3 3, label %bb4
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i3 4, label %bb5
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i3 5, label %bb6
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]
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bb: ; preds = %entry
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br label %bb8
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bb3: ; preds = %entry
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br label %bb8
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bb4: ; preds = %entry
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br label %bb8
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bb5: ; preds = %entry
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br label %bb8
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bb6: ; preds = %entry
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br label %bb8
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bb7: ; preds = %entry
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br label %bb8
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bb8: ; preds = %bb7, %bb6, %bb5, %bb4, %bb3, %bb, %entry
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%result = phi i3 [ 0, %bb7 ], [ 1, %bb6 ], [ 2, %bb5 ], [ 3, %bb4 ], [ 4, %bb3 ], [ 5, %bb ], [ 6, %entry ]
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ret i3 %result
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}
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