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