257 lines
6.8 KiB
LLVM
257 lines
6.8 KiB
LLVM
; Test merging of blocks with phi nodes.
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;
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; RUN: opt < %s -simplifycfg -S > %t
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; RUN: not grep N: %t
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; RUN: not grep X: %t
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; RUN: not grep 'switch i32[^U]+%U' %t
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; RUN: not grep "^BB.tomerge" %t
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; RUN: grep "^BB.nomerge" %t | count 4
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;
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; ModuleID = '<stdin>'
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declare i1 @foo()
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declare i1 @bar(i32)
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define i32 @test(i1 %a) {
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Q:
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br i1 %a, label %N, label %M
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N: ; preds = %Q
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br label %M
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M: ; preds = %N, %Q
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; It's ok to merge N and M because the incoming values for W are the
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; same for both cases...
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%W = phi i32 [ 2, %N ], [ 2, %Q ] ; <i32> [#uses=1]
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%R = add i32 %W, 1 ; <i32> [#uses=1]
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ret i32 %R
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}
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; Test merging of blocks with phi nodes where at least one incoming value
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; in the successor is undef.
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define i8 @testundef(i32 %u) {
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R:
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switch i32 %u, label %U [
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i32 0, label %S
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i32 1, label %T
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i32 2, label %T
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]
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S: ; preds = %R
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br label %U
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T: ; preds = %R, %R
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br label %U
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U: ; preds = %T, %S, %R
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; We should be able to merge either the S or T block into U by rewriting
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; R's incoming value with the incoming value of that predecessor since
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; R's incoming value is undef and both of those predecessors are simple
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; unconditional branches.
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%val.0 = phi i8 [ undef, %R ], [ 1, %T ], [ 0, %S ]
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ret i8 %val.0
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}
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; Test merging of blocks with phi nodes where at least one incoming value
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; in the successor is undef.
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define i8 @testundef2(i32 %u, i32* %A) {
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V:
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switch i32 %u, label %U [
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i32 0, label %W
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i32 1, label %X
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i32 2, label %X
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i32 3, label %Z
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]
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W: ; preds = %V
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br label %U
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Z:
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store i32 0, i32* %A, align 4
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br label %X
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X: ; preds = %V, %V, %Z
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br label %U
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U: ; preds = %X, %W, %V
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; We should be able to merge either the W or X block into U by rewriting
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; V's incoming value with the incoming value of that predecessor since
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; V's incoming value is undef and both of those predecessors are simple
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; unconditional branches. Note that X has predecessors beyond
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; the direct predecessors of U.
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%val.0 = phi i8 [ undef, %V ], [ 1, %X ], [ 1, %W ]
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ret i8 %val.0
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}
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define i8 @testmergesome(i32 %u, i32* %A) {
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V:
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switch i32 %u, label %Y [
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i32 0, label %W
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i32 1, label %X
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i32 2, label %X
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i32 3, label %Z
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]
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W: ; preds = %V
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store i32 1, i32* %A, align 4
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br label %Y
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Z:
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store i32 0, i32* %A, align 4
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br label %X
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X: ; preds = %V, %Z
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br label %Y
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Y: ; preds = %X, %W, %V
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; After merging X into Y, we should have 5 predecessors
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; and thus 5 incoming values to the phi.
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%val.0 = phi i8 [ 1, %V ], [ 1, %X ], [ 2, %W ]
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ret i8 %val.0
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}
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define i8 @testmergesome2(i32 %u, i32* %A) {
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V:
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switch i32 %u, label %W [
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i32 0, label %W
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i32 1, label %Y
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i32 2, label %X
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i32 4, label %Y
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]
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W: ; preds = %V
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store i32 1, i32* %A, align 4
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br label %Y
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X: ; preds = %V, %Z
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br label %Y
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Y: ; preds = %X, %W, %V
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; Ensure that we deal with both undef inputs for V when we merge in X.
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%val.0 = phi i8 [ undef, %V ], [ 1, %X ], [ 2, %W ], [ undef, %V ]
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ret i8 %val.0
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}
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; This function can't be merged
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define void @a() {
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entry:
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br label %BB.nomerge
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BB.nomerge: ; preds = %Common, %entry
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; This phi has a conflicting value (0) with below phi (2), so blocks
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; can't be merged.
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%a = phi i32 [ 1, %entry ], [ 0, %Common ] ; <i32> [#uses=1]
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br label %Succ
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Succ: ; preds = %Common, %BB.nomerge
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%b = phi i32 [ %a, %BB.nomerge ], [ 2, %Common ] ; <i32> [#uses=0]
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%conde = call i1 @foo( ) ; <i1> [#uses=1]
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br i1 %conde, label %Common, label %Exit
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Common: ; preds = %Succ
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%cond = call i1 @foo( ) ; <i1> [#uses=1]
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br i1 %cond, label %BB.nomerge, label %Succ
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Exit: ; preds = %Succ
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ret void
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}
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; This function can't be merged
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define void @b() {
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entry:
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br label %BB.nomerge
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BB.nomerge: ; preds = %Common, %entry
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br label %Succ
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Succ: ; preds = %Common, %BB.nomerge
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; This phi has confliction values for Common and (through BB) Common,
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; blocks can't be merged
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%b = phi i32 [ 1, %BB.nomerge ], [ 2, %Common ] ; <i32> [#uses=0]
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%conde = call i1 @foo( ) ; <i1> [#uses=1]
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br i1 %conde, label %Common, label %Exit
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Common: ; preds = %Succ
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%cond = call i1 @foo( ) ; <i1> [#uses=1]
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br i1 %cond, label %BB.nomerge, label %Succ
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Exit: ; preds = %Succ
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ret void
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}
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; This function can't be merged (for keeping canonical loop structures)
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define void @c() {
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entry:
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br label %BB.nomerge
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BB.nomerge: ; preds = %Common, %entry
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br label %Succ
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Succ: ; preds = %Common, %BB.tomerge, %Pre-Exit
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; This phi has identical values for Common and (through BB) Common,
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; blocks can't be merged
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%b = phi i32 [ 1, %BB.nomerge ], [ 1, %Common ], [ 2, %Pre-Exit ]
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%conde = call i1 @foo( ) ; <i1> [#uses=1]
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br i1 %conde, label %Common, label %Pre-Exit
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Common: ; preds = %Succ
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%cond = call i1 @foo( ) ; <i1> [#uses=1]
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br i1 %cond, label %BB.nomerge, label %Succ
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Pre-Exit: ; preds = %Succ
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; This adds a backedge, so the %b phi node gets a third branch and is
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; not completely trivial
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%cond2 = call i1 @foo( ) ; <i1> [#uses=1]
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br i1 %cond2, label %Succ, label %Exit
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Exit: ; preds = %Pre-Exit
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ret void
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}
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; This function can't be merged (for keeping canonical loop structures)
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define void @d() {
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entry:
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br label %BB.nomerge
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BB.nomerge: ; preds = %Common, %entry
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; This phi has a matching value (0) with below phi (0), so blocks
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; can be merged.
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%a = phi i32 [ 1, %entry ], [ 0, %Common ] ; <i32> [#uses=1]
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br label %Succ
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Succ: ; preds = %Common, %BB.tomerge
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%b = phi i32 [ %a, %BB.nomerge ], [ 0, %Common ] ; <i32> [#uses=0]
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%conde = call i1 @foo( ) ; <i1> [#uses=1]
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br i1 %conde, label %Common, label %Exit
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Common: ; preds = %Succ
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%cond = call i1 @foo( ) ; <i1> [#uses=1]
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br i1 %cond, label %BB.nomerge, label %Succ
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Exit: ; preds = %Succ
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ret void
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}
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; This function can be merged
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define void @e() {
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entry:
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br label %Succ
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Succ: ; preds = %Use, %entry
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; This phi is used somewhere else than Succ, but this should not prevent
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; merging this block
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%a = phi i32 [ 1, %entry ], [ 0, %Use ] ; <i32> [#uses=1]
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br label %BB.tomerge
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BB.tomerge: ; preds = %Succ
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%conde = call i1 @foo( ) ; <i1> [#uses=1]
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br i1 %conde, label %Use, label %Exit
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Use: ; preds = %Succ
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%cond = call i1 @bar( i32 %a ) ; <i1> [#uses=1]
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br i1 %cond, label %Succ, label %Exit
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Exit: ; preds = %Use, %Succ
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ret void
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}
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