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111
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1 /* { dg-do compile { target { i?86-*-* x86_64-*-* } } } */
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2 /* { dg-options "-O2 -fprefetch-loop-arrays -march=amdfam10 --param min-insn-to-prefetch-ratio=5 -fdump-tree-aprefetch-details" } */
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3
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4 /* These are common idioms for writing variable-length arrays at the end
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5 of structures. We should not deduce anything about the number of iterations
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6 of the loops from them. */
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7
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8 struct tail0
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9 {
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10 int xxx;
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11 int yyy[0];
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12 };
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13
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14 int loop0 (int n, struct tail0 *x)
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15 {
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16 int i, s = 0;
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17
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18 for (i = 0; i < n; i++)
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19 s += x->yyy[i];
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20
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21 return s;
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22 }
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23
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24 struct tail1
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25 {
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26 int xxx;
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27 int yyy[1];
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28 };
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29 int loop1 (int n, struct tail1 *x)
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30 {
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31 int i, s = 0;
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32
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33 for (i = 0; i < n; i++)
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34 s += x->yyy[i];
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35
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36 return s;
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37 }
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38
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39 /* It is unlikely that this should be a tail array. We may deduce that most
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40 likely, the loop iterates about 5 times, and the array is not worth prefetching. */
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41
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42 struct tail5
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43 {
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44 int xxx;
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45 int yyy[5];
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46 };
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47 int loop5 (int n, struct tail5 *x)
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48 {
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49 int i, s = 0;
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50
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51 for (i = 0; i < n; i++)
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52 s += x->yyy[i];
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53
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54 return s;
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55 }
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56
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57 /* Until we are able to track likely upper bounds, we can't really work out that
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58 small trailing arrays should not be prefetched. */
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59 /* { dg-final { scan-tree-dump-times "Issued prefetch" 2 "aprefetch" } } */
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60 /* { dg-final { scan-tree-dump-times "Not prefetching" 1 "aprefetch" } } */
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