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

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s

; Test that a switch going to a switch on the same value can be merged.
; All three switches in this example can be merged into one big one.

declare void @foo1()

declare void @foo2()

declare void @foo3()

declare void @foo4()

define void @test1(i32 %V) {
; CHECK-LABEL: @test1(
; CHECK-NEXT:    switch i32 [[V:%.*]], label [[INFLOOP:%.*]] [
; CHECK-NEXT:    i32 4, label [[A:%.*]]
; CHECK-NEXT:    i32 17, label [[B:%.*]]
; CHECK-NEXT:    i32 18, label [[B]]
; CHECK-NEXT:    i32 42, label [[D:%.*]]
; CHECK-NEXT:    ]
; CHECK:       common.ret:
; CHECK-NEXT:    ret void
; CHECK:       A:
; CHECK-NEXT:    call void @foo1()
; CHECK-NEXT:    br label [[COMMON_RET:%.*]]
; CHECK:       B:
; CHECK-NEXT:    call void @foo2()
; CHECK-NEXT:    br label [[COMMON_RET]]
; CHECK:       D:
; CHECK-NEXT:    call void @foo4()
; CHECK-NEXT:    br label [[COMMON_RET]]
; CHECK:       infloop:
; CHECK-NEXT:    br label [[INFLOOP]]
;
  switch i32 %V, label %F [
  i32 4, label %T
  i32 17, label %T
  i32 5, label %T
  i32 1234, label %F
  ]
T:              ; preds = %0, %0, %0
  switch i32 %V, label %F [
  i32 4, label %A
  i32 17, label %B
  i32 42, label %C
  ]
A:              ; preds = %T
  call void @foo1( )
  ret void
B:              ; preds = %F, %F, %T
  call void @foo2( )
  ret void
C:              ; preds = %T
  call void @foo3( )
  ret void
F:              ; preds = %F, %T, %0, %0
  switch i32 %V, label %F [
  i32 4, label %B
  i32 18, label %B
  i32 42, label %D
  ]
D:              ; preds = %F
  call void @foo4( )
  ret void

}