1; RUN: opt -gvn -S < %s | FileCheck %s
2
3; C source:
4;
5;   void f(int x) {
6;     if (x != 1)
7;       puts (x == 2 ? "a" : "b");
8;     for (;;) {
9;       puts("step 1");
10;       if (x == 2)
11;         continue;
12;       printf("step 2: %d\n", x);
13;     }
14;   }
15;
16; If we PRE %cmp3, CodeGenPrepare won't be able to sink the compare down to its
17; uses, and we are forced to keep both %x and %cmp3 in registers in the loop.
18;
19; It is just as cheap to recompute the icmp against %x as it is to compare a
20; GPR against 0. On x86-64, the br i1 %cmp3 becomes:
21;
22;   testb %r12b, %r12b
23;   jne	LBB0_3
24;
25; The sunk icmp is:
26;
27;   cmpl $2, %ebx
28;   je	LBB0_3
29;
30; This is just as good, and it doesn't require a separate register.
31;
32; CHECK-NOT: phi i1
33
34@.str = private unnamed_addr constant [2 x i8] c"a\00", align 1
35@.str1 = private unnamed_addr constant [2 x i8] c"b\00", align 1
36@.str2 = private unnamed_addr constant [7 x i8] c"step 1\00", align 1
37@.str3 = private unnamed_addr constant [12 x i8] c"step 2: %d\0A\00", align 1
38
39define void @f(i32 %x) noreturn nounwind uwtable ssp {
40entry:
41  %cmp = icmp eq i32 %x, 1
42  br i1 %cmp, label %for.cond.preheader, label %if.then
43
44if.then:                                          ; preds = %entry
45  %cmp1 = icmp eq i32 %x, 2
46  %cond = select i1 %cmp1, i8* getelementptr inbounds ([2 x i8]* @.str, i64 0, i64 0), i8* getelementptr inbounds ([2 x i8]* @.str1, i64 0, i64 0)
47  %call = tail call i32 @puts(i8* %cond) nounwind
48  br label %for.cond.preheader
49
50for.cond.preheader:                               ; preds = %entry, %if.then
51  %cmp3 = icmp eq i32 %x, 2
52  br label %for.cond
53
54for.cond:                                         ; preds = %for.cond.backedge, %for.cond.preheader
55  %call2 = tail call i32 @puts(i8* getelementptr inbounds ([7 x i8]* @.str2, i64 0, i64 0)) nounwind
56  br i1 %cmp3, label %for.cond.backedge, label %if.end5
57
58if.end5:                                          ; preds = %for.cond
59  %call6 = tail call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([12 x i8]* @.str3, i64 0, i64 0), i32 %x) nounwind
60  br label %for.cond.backedge
61
62for.cond.backedge:                                ; preds = %if.end5, %for.cond
63  br label %for.cond
64}
65
66declare i32 @puts(i8* nocapture) nounwind
67
68declare i32 @printf(i8* nocapture, ...) nounwind
69