llvm/test/Transforms/SimplifyCFG/switch_thread.ll

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -simplifycfg -S | FileCheck %s

; Test that we can thread a simple known condition through switch statements.

declare void @foo1()

declare void @foo2()

declare void @DEAD()

define void @test1(i32 %V) {
; CHECK-LABEL: @test1(
; CHECK-NEXT:    switch i32 [[V:%.*]], label [[A:%.*]] [
; CHECK-NEXT:    i32 4, label [[T:%.*]]
; CHECK-NEXT:    i32 17, label [[DONE:%.*]]
; CHECK-NEXT:    ]
; CHECK:       T:
; CHECK-NEXT:    call void @foo1()
; CHECK-NEXT:    call void @foo2()
; CHECK-NEXT:    br label [[DONE]]
; CHECK:       A:
; CHECK-NEXT:    call void @foo1()
; CHECK-NEXT:    br label [[DONE]]
; CHECK:       Done:
; CHECK-NEXT:    ret void
;
  switch i32 %V, label %A [
  i32 4, label %T
  i32 17, label %Done
  i32 1234, label %A
  ]
;; V == 4 if we get here.
T:              ; preds = %0
  call void @foo1( )
  ;; This switch is always statically determined.
  switch i32 %V, label %A2 [
  i32 4, label %B
  i32 17, label %C
  i32 42, label %C
  ]
A2:             ; preds = %T
  call void @DEAD( )
  call void @DEAD( )
  ;; always true
  %cond2 = icmp eq i32 %V, 4              ; <i1> [#uses=1]
  br i1 %cond2, label %Done, label %C
A:              ; preds = %0, %0
  call void @foo1( )
  ;; always true
  %cond = icmp ne i32 %V, 4               ; <i1> [#uses=1]
  br i1 %cond, label %Done, label %C
Done:           ; preds = %B, %A, %A2, %0
  ret void
B:              ; preds = %T
  call void @foo2( )
  ;; always true
  %cond3 = icmp eq i32 %V, 4              ; <i1> [#uses=1]
  br i1 %cond3, label %Done, label %C
C:              ; preds = %B, %A, %A2, %T, %T
  call void @DEAD( )
  ret void

}

define void @test2(i32 %V) {
; CHECK-LABEL: @test2(
; CHECK-NEXT:    switch i32 [[V:%.*]], label [[A:%.*]] [
; CHECK-NEXT:    i32 4, label [[T:%.*]]
; CHECK-NEXT:    i32 17, label [[D:%.*]]
; CHECK-NEXT:    i32 1234, label [[E:%.*]]
; CHECK-NEXT:    ]
; CHECK:       A:
; CHECK-NEXT:    call void @foo1()
; CHECK-NEXT:    [[COND:%.*]] = icmp eq i32 [[V]], 42
; CHECK-NEXT:    br i1 [[COND]], label [[D]], label [[E]]
; CHECK:       T:
; CHECK-NEXT:    call void @foo1()
; CHECK-NEXT:    call void @foo1()
; CHECK-NEXT:    ret void
; CHECK:       D:
; CHECK-NEXT:    call void @foo1()
; CHECK-NEXT:    ret void
; CHECK:       E:
; CHECK-NEXT:    ret void
;
  switch i32 %V, label %A [
  i32 4, label %T
  i32 17, label %D
  i32 1234, label %E
  ]
;; V != 4, 17, 1234 here.
A:              ; preds = %0
  call void @foo1( )
  ;; This switch is always statically determined.
  switch i32 %V, label %E [
  i32 4, label %C
  i32 17, label %C
  i32 42, label %D
  ]
;; unreacahble.
C:              ; preds = %A, %A
  call void @DEAD( )
  ret void
T:              ; preds = %0
  call void @foo1( )
  call void @foo1( )
  ret void
D:              ; preds = %A, %0
  call void @foo1( )
  ret void
E:              ; preds = %A, %0
  ret void

}