1; In this test we check how heuristics for complete unrolling work. We have
2; three knobs:
3;  1) -unroll-threshold
4;  3) -unroll-percent-dynamic-cost-saved-threshold and
5;  2) -unroll-dynamic-cost-savings-discount
6;
7; They control loop-unrolling according to the following rules:
8;  * If size of unrolled loop exceeds the absoulte threshold, we don't unroll
9;    this loop under any circumstances.
10;  * If size of unrolled loop is below the '-unroll-threshold', then we'll
11;    consider this loop as a very small one, and completely unroll it.
12;  * If a loop size is between these two tresholds, we only do complete unroll
13;    it if estimated number of potentially optimized instructions is high (we
14;    specify the minimal percent of such instructions).
15
16; In this particular test-case, complete unrolling will allow later
17; optimizations to remove ~55% of the instructions, the loop body size is 9,
18; and unrolled size is 65.
19
20; RUN: opt < %s -S -loop-unroll -unroll-max-iteration-count-to-analyze=1000 -unroll-threshold=10  -unroll-percent-dynamic-cost-saved-threshold=20 -unroll-dynamic-cost-savings-discount=0 | FileCheck %s -check-prefix=TEST1
21; RUN: opt < %s -S -loop-unroll -unroll-max-iteration-count-to-analyze=1000 -unroll-threshold=10  -unroll-percent-dynamic-cost-saved-threshold=20 -unroll-dynamic-cost-savings-discount=90 | FileCheck %s -check-prefix=TEST2
22; RUN: opt < %s -S -loop-unroll -unroll-max-iteration-count-to-analyze=1000 -unroll-threshold=10  -unroll-percent-dynamic-cost-saved-threshold=80 -unroll-dynamic-cost-savings-discount=90 | FileCheck %s -check-prefix=TEST3
23; RUN: opt < %s -S -loop-unroll -unroll-max-iteration-count-to-analyze=1000 -unroll-threshold=100 -unroll-percent-dynamic-cost-saved-threshold=80 -unroll-dynamic-cost-savings-discount=0 | FileCheck %s -check-prefix=TEST4
24
25; If the absolute threshold is too low, or if we can't optimize away requested
26; percent of instructions, we shouldn't unroll:
27; TEST1: %array_const_idx = getelementptr inbounds [9 x i32], [9 x i32]* @known_constant, i64 0, i64 %iv
28; TEST3: %array_const_idx = getelementptr inbounds [9 x i32], [9 x i32]* @known_constant, i64 0, i64 %iv
29
30; Otherwise, we should:
31; TEST2-NOT: %array_const_idx = getelementptr inbounds [9 x i32], [9 x i32]* @known_constant, i64 0, i64 %iv
32
33; Also, we should unroll if the 'unroll-threshold' is big enough:
34; TEST4-NOT: %array_const_idx = getelementptr inbounds [9 x i32], [9 x i32]* @known_constant, i64 0, i64 %iv
35
36; And check that we don't crash when we're not allowed to do any analysis.
37; RUN: opt < %s -loop-unroll -unroll-max-iteration-count-to-analyze=0 -disable-output
38target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
39
40@known_constant = internal unnamed_addr constant [9 x i32] [i32 0, i32 -1, i32 0, i32 -1, i32 5, i32 -1, i32 0, i32 -1, i32 0], align 16
41
42define i32 @foo(i32* noalias nocapture readonly %src) {
43entry:
44  br label %loop
45
46loop:                                                ; preds = %loop, %entry
47  %iv = phi i64 [ 0, %entry ], [ %inc, %loop ]
48  %r  = phi i32 [ 0, %entry ], [ %add, %loop ]
49  %arrayidx = getelementptr inbounds i32, i32* %src, i64 %iv
50  %src_element = load i32, i32* %arrayidx, align 4
51  %array_const_idx = getelementptr inbounds [9 x i32], [9 x i32]* @known_constant, i64 0, i64 %iv
52  %const_array_element = load i32, i32* %array_const_idx, align 4
53  %mul = mul nsw i32 %src_element, %const_array_element
54  %add = add nsw i32 %mul, %r
55  %inc = add nuw nsw i64 %iv, 1
56  %exitcond86.i = icmp eq i64 %inc, 9
57  br i1 %exitcond86.i, label %loop.end, label %loop
58
59loop.end:                                            ; preds = %loop
60  %r.lcssa = phi i32 [ %r, %loop ]
61  ret i32 %r.lcssa
62}
63