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llvm-6502/test/Transforms/LCSSA/unused-phis.ll

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Do not add PHIs with no users when creating LCSSA form. Patch by Andrew Clinton. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127674 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-15 07:41:25 +00:00
; RUN: opt < %s -lcssa -S | FileCheck %s
; CHECK: exit1:
; CHECK: .lcssa =
; CHECK: exit2:
Enable the new LoopInfo algorithm by default. 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
2012-06-26 04:11:38 +00:00
; CHECK: .lcssa1 =
Do not add PHIs with no users when creating LCSSA form. Patch by Andrew Clinton. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127674 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-15 07:41:25 +00:00
; CHECK: exit3:
Enable the new LoopInfo algorithm by default. 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
2012-06-26 04:11:38 +00:00
; CHECK-NOT: .lcssa
Do not add PHIs with no users when creating LCSSA form. Patch by Andrew Clinton. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127674 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-15 07:41:25 +00:00
; Test to ensure that when there are multiple exit blocks, PHI nodes are
; only inserted by LCSSA when there is a use dominated by a given exit
; block.
declare void @printf(i32 %i)
define i32 @unused_phis() nounwind {
entry:
br label %loop
loop:
%i = phi i32 [0, %entry], [1, %then2]
br i1 undef, label %exit1, label %then1
then1:
br i1 undef, label %exit2, label %then2
then2:
br i1 undef, label %exit3, label %loop
exit1:
call void @printf(i32 %i)
ret i32 %i
exit2:
ret i32 %i
exit3:
ret i32 0
}
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