http://llvm.org/bugs/show_bug.cgi?id=17677
Bug ID: 17677
Summary: [Vectorizer] Implement stride access
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: Loop Optimizer
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Classification: Unclassified
Implement stride access detection for induction variables with Step > 1, with
cost-model support for the (currently unclear) benefits, and make sure that the
vectorization happens later on.
The basic loop in which this should work is:
for (i..N/3) {
a[3*i] = b[3*i];
a[3*i+1] = b[3*i+1];
a[3*i+2] = b[3*i+2];
}
With S = sizeof(a[0]);
Since the loop stride is { 3 * S } and the evolutions are:
{a, +, 3S}
{a+S, +, 3S}
{a+2S, +, 3S}
The reads/writes don't overlap, and they're sequential, so we can vectorize.
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