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
59
60
61
62
63
| ; RUN: opt -passes='loop-vectorize' -debug -S < %s 2>&1 | FileCheck %s
; REQUIRES: asserts
; This checks we don't crash when the inner loop we're trying to vectorize
; is a SCEV AddRec with respect to an outer loop.
; In this case, the problematic PHI is:
; %0 = phi i32 [ undef, %for.cond1.preheader ], [ %inc54, %for.body3 ]
; Since %inc54 is the IV of the outer loop, and %0 equivalent to it,
; we get the situation described above.
; Code that leads to this situation can look something like:
;
; int a, b[1], c;
; void fn1 ()
; {
; for (; c; c++)
; for (a = 0; a; a++)
; b[c] = 4;
; }
;
; The PHI is an artifact of the register promotion of c.
; Note that we can no longer get the vectorizer to actually see such PHIs,
; because LV now simplifies the loop internally, but the test is still
; useful as a regression test, and in case loop-simplify behavior changes.
@c = external global i32, align 4
@a = external global i32, align 4
@b = external global [1 x i32], align 4
; We can vectorize this loop because we are storing an invariant value into an
; invariant address.
; CHECK: LV: We can vectorize this loop!
; CHECK-LABEL: @test
define void @test() {
entry:
%a.promoted2 = load i32, i32* @a, align 1
%c.promoted = load i32, i32* @c, align 1
br label %for.cond1.preheader
for.cond1.preheader: ; preds = %for.cond1.for.inc4_crit_edge, %entry
%inc54 = phi i32 [ %inc5, %for.cond1.for.inc4_crit_edge ], [ %c.promoted, %entry ]
%inc.lcssa3 = phi i32 [ %inc.lcssa, %for.cond1.for.inc4_crit_edge ], [ %a.promoted2, %entry ]
br label %for.body3
for.body3: ; preds = %for.body3, %for.cond1.preheader
%inc1 = phi i32 [ %inc.lcssa3, %for.cond1.preheader ], [ %inc, %for.body3 ]
%0 = phi i32 [ undef, %for.cond1.preheader ], [ %inc54, %for.body3 ]
%idxprom = sext i32 %0 to i64
%arrayidx = getelementptr inbounds [1 x i32], [1 x i32]* @b, i64 0, i64 %idxprom
store i32 4, i32* %arrayidx, align 4
%inc = add nsw i32 %inc1, 1
%tobool2 = icmp eq i32 %inc, 0
br i1 %tobool2, label %for.cond1.for.inc4_crit_edge, label %for.body3
for.cond1.for.inc4_crit_edge: ; preds = %for.body3
%inc.lcssa = phi i32 [ %inc, %for.body3 ]
%.lcssa = phi i32 [ %inc54, %for.body3 ]
%inc5 = add nsw i32 %.lcssa, 1
br label %for.cond1.preheader
}
|