1; RUN: llc -march=avr -print-after=expand-isel-pseudos -cgp-freq-ratio-to-skip-merge=10 < %s 2>&1 | FileCheck %s
2
3; Because `switch` seems to trigger Machine Basic Blocks to be ordered
4; in a different order than they were constructed, this exposes an
5; error in the `expand-isel-pseudos` pass. Specifically, it thought we
6; could always fallthrough to a newly-constructed MBB. However,
7; there's no guarantee that either of the constructed MBBs need to
8; occur immediately after the currently-focused one!
9;
10; This issue manifests in a CFG that looks something like this:
11;
12; %bb.2.finish:
13;     successors: %bb.5(?%) %bb.6(?%)
14;     Predecessors according to CFG: %bb.0 %bb.1
15;         %0 = PHI %3, <%bb.0>, %5, <%bb.1>
16;         %7 = LDIRdK 2
17;         %8 = LDIRdK 1
18;         CPRdRr %2, %0, implicit-def %SREG
19;         BREQk <%bb.6>, implicit %SREG
20;
21; The code assumes it the fallthrough block after this is %bb.5, but
22; it's actually %bb.3! To be proper, there should be an unconditional
23; jump tying this block to %bb.5.
24
25define i8 @select_must_add_unconditional_jump(i8 %arg0, i8 %arg1) unnamed_addr {
26entry-block:
27  switch i8 %arg0, label %dead [
28    i8 0, label %zero
29    i8 1, label %one
30  ]
31
32zero:
33  br label %finish
34
35one:
36  br label %finish
37
38finish:
39  %predicate = phi i8 [ 50, %zero ], [ 100, %one ]
40  %is_eq = icmp eq i8 %arg1, %predicate
41  %result = select i1 %is_eq, i8 1, i8 2
42  ret i8 %result
43
44dead:
45  ret i8 0
46}
47
48; This check may be a bit brittle, but the important thing is that the
49; basic block containing `select` needs to contain explicit jumps to
50; both successors.
51
52; CHECK: bb.2.finish:
53; CHECK: successors:
54; CHECK: BREQk [[BRANCHED:%bb.[0-9]+]]
55; CHECK: RJMPk [[DIRECT:%bb.[0-9]+]]
56; CHECK-SAME-DAG: {{.*}}[[BRANCHED]]
57; CHECK-SAME-DAG: {{.*}}[[DIRECT]]
58; CHECK: bb.3.dead:
59