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Diffstat (limited to 'gcc/testsuite/gcc.dg/tree-ssa-chrec/ssa-chrec-09.c')
| -rw-r--r-- | gcc/testsuite/gcc.dg/tree-ssa-chrec/ssa-chrec-09.c | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/gcc/testsuite/gcc.dg/tree-ssa-chrec/ssa-chrec-09.c b/gcc/testsuite/gcc.dg/tree-ssa-chrec/ssa-chrec-09.c new file mode 100644 index 00000000000..9964a6d30c2 --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa-chrec/ssa-chrec-09.c @@ -0,0 +1,41 @@ +/* { dg-do compile } */ +/* { dg-options "-O1 -fscalar-evolutions -fdump-tree-scev-details" } */ + +int main(void) +{ + int a = -100; + int b = 2; + int c = 3; + int d = 4; + int e = 5; + + while (a) + { + /* Exercises the cycle detector: a -> b -> (c -> d -> e -> c)*. */ + a += b; + b += c; + c += d; + d += e; + e += c; + } +} + +/* This is what is commonly called a "mixer". It whirls the data in a + strongly connected component. We expect the following evolution + functions: + + e -> {5, +, c_13}_1 + d -> {4, +, {5, +, c_13}_1}_1 + c -> {3, +, {4, +, {5, +, c_13}_1}_1}_1 + b -> {2, +, {3, +, {4, +, {5, +, c_13}_1}_1}_1}_1 + a -> {-100, +, {2, +, {3, +, {4, +, {5, +, c_13}_1}_1}_1}_1}_1 +*/ + +/* FIXME: + For the moment this testcase does not test for anything, but for + not ICEing, and for documentation purposes (okay here is the + definition of a mixer). However, I'm considering testing something + around the lines of ssa-chrec-08.c, ie. build two mixers, and then + compare their values. But that is difficult, and low priority. */ + + |