third_party/llvm-7.0/llvm/test/Analysis/MustExecute/loop-header.ll

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -disable-output -print-mustexecute %s 2>&1 | FileCheck %s

define i1 @header_with_icf(i32* noalias %p, i32 %high) {
; CHECK-LABEL: @header_with_icf(
; CHECK-LABEL:       loop:
; CHECK:         %iv = phi i32 [ 0, %entry ], [ %iv.next, %loop ] ; (mustexec in: loop)
; CHECK:          %v = load i32, i32* %p ; (mustexec in: loop)
; CHECK:          call void @maythrow_and_use(i32 %v)	; (mustexec in: loop)
; CHECK-NOT: mustexec

entry:
  br label %loop

loop:
  %iv = phi i32 [0, %entry], [%iv.next, %loop]
  %v = load i32, i32* %p
  call void @maythrow_and_use(i32 %v)
  %iv.next = add nsw nuw i32 %iv, 1
  %exit.test = icmp slt i32 %iv, %high
  br i1 %exit.test, label %exit, label %loop

exit:
  ret i1 false
}

define i1 @split_header(i32* noalias %p, i32 %high) {
; CHECK-LABEL: @split_header(
; CHECK-LABEL:       loop:
; CHECK:          %iv = phi i32 [ 0, %entry ], [ %iv.next, %next ]	; (mustexec in: loop)
; CHECK:          %v = load i32, i32* %p ; (mustexec in: loop)
; CHECK:          br label %next ; (mustexec in: loop)
; CHECK-NOT: mustexec
entry:
  br label %loop

loop:
  %iv = phi i32 [0, %entry], [%iv.next, %next]
  %v = load i32, i32* %p
  br label %next
next:
  call void @maythrow_and_use(i32 %v)
  %iv.next = add nsw nuw i32 %iv, 1
  %exit.test = icmp slt i32 %iv, %high
  br i1 %exit.test, label %exit, label %loop

exit:
  ret i1 false
}

; FIXME: everything in inner loop header should be must execute
; for outer as well
define i1 @nested(i32* noalias %p, i32 %high) {
; CHECK-LABEL: @nested
; CHECK-LABEL: loop:                                             ; preds = %next
; CHECK:         %iv = phi i32 [ 0, %entry ], [ %iv.next, %next ]	; (mustexec in: loop)
; CHECK:         br label %inner_loop	; (mustexec in: loop)
; CHECK-LABEL: inner_loop:
; CHECK:         %v = load i32, i32* %p	; (mustexec in: inner_loop)
; CHECK:         %inner.test = icmp eq i32 %v, 0	; (mustexec in: inner_loop)
; CHECK:         br i1 %inner.test, label %inner_loop, label %next	; (mustexec in: inner_loop)
; CHECK-NOT: mustexec

entry:
  br label %loop

loop:
  %iv = phi i32 [0, %entry], [%iv.next, %next]
  br label %inner_loop
  
inner_loop:
  %v = load i32, i32* %p
  %inner.test = icmp eq i32 %v, 0
  br i1 %inner.test, label %inner_loop, label %next

next:
  call void @maythrow_and_use(i32 %v)
  %iv.next = add nsw nuw i32 %iv, 1
  %exit.test = icmp slt i32 %iv, %high
  br i1 %exit.test, label %exit, label %loop

exit:
  ret i1 false
}

; Since all the instructions in the loop dominate the only exit
; and there's no implicit control flow in the loop, all must execute
; FIXME: handled by loop safety info, test it
define i1 @nothrow_loop(i32* noalias %p, i32 %high) {
; CHECK-LABEL: @nothrow_loop(
; CHECK-LABEL:  loop:
; CHECK:         %iv = phi i32 [ 0, %entry ], [ %iv.next, %next ] ; (mustexec in: loop)
; CHECK:          br label %next ; (mustexec in: loop)
; CHECK-LABEL: next:
; CHECK:          %v = load i32, i32* %p ; (mustexec in: loop)
; CHECK:          %iv.next = add nuw nsw i32 %iv, 1 ; (mustexec in: loop)
; CHECK:          %exit.test = icmp slt i32 %iv, %high ; (mustexec in: loop)
; CHECK:          br i1 %exit.test, label %exit, label %loop ; (mustexec in: loop)
; CHECK-NOT: mustexec

entry:
  br label %loop

loop:
  %iv = phi i32 [0, %entry], [%iv.next, %next]
  br label %next
next:
  %v = load i32, i32* %p
  %iv.next = add nsw nuw i32 %iv, 1
  %exit.test = icmp slt i32 %iv, %high
  br i1 %exit.test, label %exit, label %loop

exit:
  ret i1 false
}


declare void @maythrow_and_use(i32)