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3 Commits

Author SHA1 Message Date
Arnold Schwaighofer
0a98597e80 Reapply 184685 after the SetVector iteration order fix.
This should hopefully have fixed the stage2/stage3 miscompare on the dragonegg
testers.

"LoopVectorize: Use the dependence test utility class

We now no longer need alias analysis - the cases that alias analysis would
handle are now handled as accesses with a large dependence distance.

We can now vectorize loops with simple constant dependence distances.

  for (i = 8; i < 256; ++i) {
    a[i] = a[i+4] * a[i+8];
  }

  for (i = 8; i < 256; ++i) {
    a[i] = a[i-4] * a[i-8];
  }

We would be able to vectorize about 200 more loops (in many cases the cost model
instructs us no to) in the test suite now. Results on x86-64 are a wash.

I have seen one degradation in ammp. Interestingly, the function in which we
now vectorize a loop is never executed so we probably see some instruction
cache effects. There is a 2% improvement in h264ref. There is one or the other
TSCV loop kernel that speeds up.

radar://13681598"

llvm-svn: 184724
2013-06-24 12:09:15 +00:00
Arnold Schwaighofer
f022b11b08 Revert "LoopVectorize: Use the dependence test utility class"
This reverts commit cbfa1ca993363ca5c4dbf6c913abc957c584cbac.

We are seeing a stage2 and stage3 miscompare on some dragonegg bots.

llvm-svn: 184690
2013-06-24 06:10:41 +00:00
Arnold Schwaighofer
c49cd1a668 LoopVectorize: Use the dependence test utility class
We now no longer need alias analysis - the cases that alias analysis would
handle are now handled as accesses with a large dependence distance.

We can now vectorize loops with simple constant dependence distances.

  for (i = 8; i < 256; ++i) {
    a[i] = a[i+4] * a[i+8];
  }

  for (i = 8; i < 256; ++i) {
    a[i] = a[i-4] * a[i-8];
  }

We would be able to vectorize about 200 more loops (in many cases the cost model
instructs us no to) in the test suite now. Results on x86-64 are a wash.

I have seen one degradation in ammp. Interestingly, the function in which we
now vectorize a loop is never executed so we probably see some instruction
cache effects. There is a 2% improvement in h264ref. There is one or the other
TSCV loop kernel that speeds up.

radar://13681598

llvm-svn: 184685
2013-06-24 03:55:48 +00:00