third_party/llvm-7.0/llvm/test/Transforms/LoopUnroll/convergent.ll

; RUN: opt < %s -loop-unroll -unroll-runtime -unroll-allow-partial -S | FileCheck %s

declare void @f() convergent

; Although this loop contains a convergent instruction, it should be
; fully unrolled.
;
; CHECK-LABEL: @full_unroll(
define i32 @full_unroll() {
entry:
  br label %l3

l3:
  %x.0 = phi i32 [ 0, %entry ], [ %inc, %l3 ]
; CHECK: call void @f()
; CHECK: call void @f()
; CHECK: call void @f()
; CHECK-NOT: call void @f()
  call void @f() ;convergent
  %inc = add nsw i32 %x.0, 1
  %exitcond = icmp eq i32 %inc, 3
  br i1 %exitcond, label %exit, label %l3

exit:
  ret i32 0
}

; This loop contains a convergent instruction, but it should be partially
; unrolled.  The unroll count is the largest power of 2 that divides the
; multiple -- 4, in this case.
;
; CHECK-LABEL: @runtime_unroll(
define i32 @runtime_unroll(i32 %n) {
entry:
  %loop_ctl = mul nsw i32 %n, 12
  br label %l3

l3:
  %x.0 = phi i32 [ 0, %entry ], [ %inc, %l3 ]
; CHECK: call void @f()
; CHECK: call void @f()
; CHECK: call void @f()
; CHECK: call void @f()
; CHECK-NOT: call void @f()
  call void @f() convergent
  %inc = add nsw i32 %x.0, 1
  %exitcond = icmp eq i32 %inc, %loop_ctl
  br i1 %exitcond, label %exit, label %l3

exit:
  ret i32 0
}

; This loop contains a convergent instruction, so its partial unroll
; count must divide its trip multiple.  This overrides its unroll
; pragma -- we unroll exactly 8 times, even though 16 is requested.
; CHECK-LABEL: @pragma_unroll
define i32 @pragma_unroll(i32 %n) {
entry:
  %loop_ctl = mul nsw i32 %n, 24
  br label %l3, !llvm.loop !0

l3:
  %x.0 = phi i32 [ 0, %entry ], [ %inc, %l3 ]
; CHECK: call void @f()
; CHECK: call void @f()
; CHECK: call void @f()
; CHECK: call void @f()
; CHECK: call void @f()
; CHECK: call void @f()
; CHECK: call void @f()
; CHECK: call void @f()
; CHECK-NOT: call void @f()
  call void @f() convergent
  %inc = add nsw i32 %x.0, 1
  %exitcond = icmp eq i32 %inc, %loop_ctl
  br i1 %exitcond, label %exit, label %l3, !llvm.loop !0

exit:
  ret i32 0
}

; This loop contains a convergent instruction. Since the pragma loop unroll
; count 2 divides trip count 4. The loop unroll should respect the pragma.
; CHECK-LABEL: @pragma_unroll_divisible_trip_count
define void @pragma_unroll_divisible_trip_count() {
entry:
  br label %l3, !llvm.loop !1

l3:
  %x.0 = phi i32 [ 0, %entry ], [ %inc, %l3 ]
; CHECK: call void @f()
; CHECK: call void @f()
; CHECK-NOT: call void @f()
  call void @f() convergent
  %inc = add nsw i32 %x.0, 1
  %exitcond = icmp eq i32 %inc, 4
  br i1 %exitcond, label %exit, label %l3, !llvm.loop !1

exit:
  ret void
}

; This loop contains a convergent instruction. Since the pragma loop unroll
; count 2 divides trip multiple 2. The loop unroll should respect the pragma.
; CHECK-LABEL: @pragma_unroll_divisible_trip_multiple
define i32 @pragma_unroll_divisible_trip_multiple(i32 %n) {
entry:
  %loop_ctl = mul nsw i32 %n, 2
  br label %l3, !llvm.loop !1

l3:
  %x.0 = phi i32 [ 0, %entry ], [ %inc, %l3 ]
; CHECK: call void @f()
; CHECK: call void @f()
; CHECK-NOT: call void @f()
  call void @f() convergent
  %inc = add nsw i32 %x.0, 1
  %exitcond = icmp eq i32 %inc, %loop_ctl
  br i1 %exitcond, label %exit, label %l3, !llvm.loop !1

exit:
  ret i32 0
}

; This loop contains a convergent instruction. Since the pragma loop unroll
; count 2 is unknown to divide runtime trip count, the loop is not unrolled
; since remainder is forbidden for unrolling convergent loop.
; ToDo: Forbidding remainder for unrolling convergent loop may be relaxed
; in the future.
; CHECK-LABEL: @pragma_unroll_indivisible_runtime_trip_count
define i32 @pragma_unroll_indivisible_runtime_trip_count(i32 %n) {
entry:
  br label %l3, !llvm.loop !1

l3:
  %x.0 = phi i32 [ 0, %entry ], [ %inc, %l3 ]
; CHECK: call void @f()
; CHECK-NOT: call void @f()
  call void @f() convergent
  %inc = add nsw i32 %x.0, 1
  %exitcond = icmp eq i32 %inc, %n
  br i1 %exitcond, label %exit, label %l3, !llvm.loop !1

exit:
  ret i32 0
}

; This loop contains a convergent instruction. Since the pragma loop unroll
; count 2 does not divide trip count 5, the loop is not unrolled by 2
; since remainder is forbidden for unrolling convergent loop. Instead, the
; loop gets fully unrolled.
; ToDo: Forbidding remainder for unrolling convergent loop may be relaxed
; in the future.
; CHECK-LABEL: @pragma_unroll_indivisible_trip_count
define i32 @pragma_unroll_indivisible_trip_count() {
entry:
  br label %l3, !llvm.loop !1

l3:
  %x.0 = phi i32 [ 0, %entry ], [ %inc, %l3 ]
; CHECK: call void @f()
; CHECK: call void @f()
; CHECK: call void @f()
; CHECK: call void @f()
; CHECK: call void @f()
; CHECK-NOT: call void @f()
  call void @f() convergent
  %inc = add nsw i32 %x.0, 1
  %exitcond = icmp eq i32 %inc, 5
  br i1 %exitcond, label %exit, label %l3, !llvm.loop !1

exit:
  ret i32 0
}

!0 = !{!0, !{!"llvm.loop.unroll.count", i32 16}}
!1 = !{!1, !{!"llvm.loop.unroll.count", i32 2}}