Chris Lattner | 830b529 | 2002-05-02 20:41:39 +0000 | [diff] [blame] | 1 | ; edgefailure - This function illustrates how SCCP is not doing it's job. This |
| 2 | ; function should be optimized almost completely away: the loop should be |
| 3 | ; analyzed to detect that the body executes exactly once, and thus the branch |
| 4 | ; can be eliminated and code becomes trivially dead. This is distilled from a |
| 5 | ; real benchmark (mst from Olden benchmark, MakeGraph function). When SCCP is |
| 6 | ; fixed, this should be eliminated by a single SCCP application. |
| 7 | ; |
| 8 | ; RUN: if as < %s | opt -sccp | dis | grep loop |
| 9 | ; RUN: then exit 1 |
| 10 | ; RUN: else exit 0 |
| 11 | ; RUN: fi |
| 12 | |
| 13 | int *"test"() |
| 14 | begin |
| 15 | bb1: |
| 16 | %A = malloc int |
| 17 | br label %bb2 |
| 18 | bb2: |
| 19 | %i = phi int [ %i2, %bb2 ], [ 0, %bb1 ] ;; Always 0 |
| 20 | %i2 = add int %i, 1 ;; Always 1 |
| 21 | store int %i, int *%A |
| 22 | %loop = setle int %i2, 0 ;; Always false |
| 23 | br bool %loop, label %bb2, label %bb3 |
| 24 | |
| 25 | bb3: |
| 26 | ret int * %A |
| 27 | end |
| 28 | |