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