llvm-project/llvm/test/Transforms/SimplifyCFG/indirectbr.ll

; RUN: opt -S -simplifycfg < %s | FileCheck %s

; SimplifyCFG should eliminate redundant indirectbr edges.

; CHECK: indbrtest0
; CHECK: indirectbr i8* %t, [label %BB0, label %BB1, label %BB2]
; CHECK: %x = phi i32 [ 0, %BB0 ], [ 1, %entry ]

declare void @foo()
declare void @A()
declare void @B(i32)
declare void @C()

define void @indbrtest0(i8** %P, i8** %Q) {
entry:
  store i8* blockaddress(@indbrtest0, %BB0), i8** %P
  store i8* blockaddress(@indbrtest0, %BB1), i8** %P
  store i8* blockaddress(@indbrtest0, %BB2), i8** %P
  call void @foo()
  %t = load i8** %Q
  indirectbr i8* %t, [label %BB0, label %BB1, label %BB2, label %BB0, label %BB1, label %BB2]
BB0:
  call void @A()
  br label %BB1
BB1:
  %x = phi i32 [ 0, %BB0 ], [ 1, %entry ], [ 1, %entry ]
  call void @B(i32 %x)
  ret void
BB2:
  call void @C()
  ret void
}

; SimplifyCFG should convert the indirectbr into a directbr. It would be even
; better if it removed the branch altogether, but simplifycfdg currently misses
; that because the predecessor is the entry block.

; CHECK: indbrtest1
; CHECK: br label %BB0

define void @indbrtest1(i8** %P, i8** %Q) {
entry:
  store i8* blockaddress(@indbrtest1, %BB0), i8** %P
  call void @foo()
  %t = load i8** %Q
  indirectbr i8* %t, [label %BB0, label %BB0]
BB0:
  call void @A()
  ret void
}

; SimplifyCFG should notice that BB0 does not have its address taken and
; remove it from entry's successor list.

; CHECK: indbrtest2
; CHECK: entry:
; CHECK-NEXT: unreachable

define void @indbrtest2(i8* %t) {
entry:
  indirectbr i8* %t, [label %BB0, label %BB0]
BB0:
  ret void
}


; Make sure the blocks in the next few tests aren't trivially removable as
; successors by taking their addresses.

@anchor = constant [13 x i8*] [
  i8* blockaddress(@indbrtest3, %L1), i8* blockaddress(@indbrtest3, %L2), i8* blockaddress(@indbrtest3, %L3),
  i8* blockaddress(@indbrtest4, %L1), i8* blockaddress(@indbrtest4, %L2), i8* blockaddress(@indbrtest4, %L3),
  i8* blockaddress(@indbrtest5, %L1), i8* blockaddress(@indbrtest5, %L2), i8* blockaddress(@indbrtest5, %L3), i8* blockaddress(@indbrtest5, %L4),
  i8* blockaddress(@indbrtest6, %L1), i8* blockaddress(@indbrtest6, %L2), i8* blockaddress(@indbrtest6, %L3)
]

; SimplifyCFG should turn the indirectbr into a conditional branch on the
; condition of the select.

; CHECK: @indbrtest3
; CHECK-NEXT: entry:
; CHECK-NEXT: br i1 %cond, label %L1, label %L2
; CHECK-NOT: indirectbr
; CHECK-NOT: br
; CHECK-NOT: L3:
define void @indbrtest3(i1 %cond, i8* %address) nounwind {
entry:
  %indirect.goto.dest = select i1 %cond, i8* blockaddress(@indbrtest3, %L1), i8* blockaddress(@indbrtest3, %L2)
  indirectbr i8* %indirect.goto.dest, [label %L1, label %L2, label %L3]

L1:
  call void @A()
  ret void
L2:
  call void @C()
  ret void
L3:
  call void @foo()
  ret void
}

; SimplifyCFG should turn the indirectbr into an unconditional branch to the
; only possible destination.
; As in @indbrtest1, it should really remove the branch entirely, but it doesn't
; because it's in the entry block.

; CHECK: @indbrtest4
; CHECK-NEXT: entry:
; CHECK-NEXT: br label %L1
define void @indbrtest4(i1 %cond) nounwind {
entry:
  %indirect.goto.dest = select i1 %cond, i8* blockaddress(@indbrtest4, %L1), i8* blockaddress(@indbrtest4, %L1)
  indirectbr i8* %indirect.goto.dest, [label %L1, label %L2, label %L3]

L1:
  call void @A()
  ret void
L2:
  call void @C()
  ret void
L3:
  call void @foo()
  ret void
}

; SimplifyCFG should turn the indirectbr into an unreachable because neither
; destination is listed as a successor.

; CHECK: @indbrtest5
; CHECK-NEXT: entry:
; CHECK-NEXT: unreachable
; CHECK-NEXT: }
define void @indbrtest5(i1 %cond, i8* %anchor) nounwind {
entry:
  %indirect.goto.dest = select i1 %cond, i8* blockaddress(@indbrtest5, %L1), i8* blockaddress(@indbrtest5, %L2)
; This needs to have more than one successor for this test, otherwise it gets
; replaced with an unconditional branch to the single successor.
  indirectbr i8* %indirect.goto.dest, [label %L3, label %L4]

L1:
  call void @A()
  ret void
L2:
  call void @C()
  ret void
L3:
  call void @foo()
  ret void
L4:
  call void @foo()

; This keeps blockaddresses not otherwise listed as successors from being zapped
; before SimplifyCFG even looks at the indirectbr.
  indirectbr i8* %anchor, [label %L1, label %L2]
}

; The same as above, except the selected addresses are equal.

; CHECK: @indbrtest6
; CHECK-NEXT: entry:
; CHECK-NEXT: unreachable
; CHECK-NEXT: }
define void @indbrtest6(i1 %cond, i8* %anchor) nounwind {
entry:
  %indirect.goto.dest = select i1 %cond, i8* blockaddress(@indbrtest6, %L1), i8* blockaddress(@indbrtest6, %L1)
; This needs to have more than one successor for this test, otherwise it gets
; replaced with an unconditional branch to the single successor.
  indirectbr i8* %indirect.goto.dest, [label %L2, label %L3]

L1:
  call void @A()
  ret void
L2:
  call void @C()
  ret void
L3:
  call void @foo()

; This keeps blockaddresses not otherwise listed as successors from being zapped
; before SimplifyCFG even looks at the indirectbr.
  indirectbr i8* %anchor, [label %L1, label %L2]
}