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b711924e7a
The cost of predicating a diamond is only the instructions that are not shared between the two branches. Additionally If a predicate clobbering instruction occurs in the shared portion of the branches (e.g. a cond move), it may still be possible to if convert the sub-cfg. This change handles these two facts by rescanning the non-shared portion of a diamond sub-cfg to recalculate both the predication cost and whether both blocks are pred-clobbering. Fixed 2 bugs before recommitting. Branch instructions must be compared and found identical before diamond conversion. Also, predicate-clobbering instructions in the shared prefix disqualifies a potential diamond conversion. Includes tests for both. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279670 91177308-0d34-0410-b5e6-96231b3b80d8
37 lines
1.2 KiB
LLVM
37 lines
1.2 KiB
LLVM
; RUN: llc -O2 -o - %s | FileCheck %s
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target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
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target triple = "thumbv7-unknown-linux-gnueabihf"
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; Function Attrs: argmemonly nounwind
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declare void @llvm.lifetime.start(i64, i8* nocapture) #0
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; Function Attrs: nounwind
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declare void @_ZNSaIcEC2Ev() unnamed_addr #0 align 2
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declare void @_ZNSsC1EPKcRKSaIcE() unnamed_addr #0
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; It isn't valid to If-Convert the following function, even though the calls
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; are in common. The calls clobber the predicate info.
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; CHECK: cbnz r{{[0-9]+}}, .LBB0_2
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; CHECK: BB#1
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; CHECK: .LBB0_2
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; Function Attrs: nounwind
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define hidden void @_ZN4llvm14DOTGraphTraitsIPNS_13ScheduleDAGMIEE17getEdgeAttributesEPKNS_5SUnitENS_13SUnitIteratorEPKNS_11ScheduleDAGE() #0 align 2 {
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br i1 undef, label %1, label %2
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; <label>:1: ; preds = %0
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call void @_ZNSaIcEC2Ev() #0
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call void @_ZNSsC1EPKcRKSaIcE()
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br label %3
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; <label>:2: ; preds = %0
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call void @llvm.lifetime.start(i64 1, i8* undef) #0
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call void @_ZNSaIcEC2Ev() #0
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br label %3
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; <label>:3: ; preds = %2, %1
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ret void
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}
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attributes #0 = { nounwind }
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