[PATCH] D85410: [ARM][MVE] Allow loops containing strides != 1 to be tail predicated with gather/scatters enabled

[Dave Green via Phabricator via llvm-commits]

dmgreen added inline comments.


================
Comment at: llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp:1631
           continue;
-        }
-        if (Stride != NextStride) {
-          LLVM_DEBUG(dbgs() << "Different strides found, can't "
-                               "tail-predicate\n.");
+        } else if (NextStride == 2) {
+          LLVM_DEBUG(dbgs()
----------------
Can you change this condition to something like
  if (NextStride == -1 || (NextStride == 2 && MVEMaxSupportedInterleaveFactor >= 2) || (NextStride == 4 && MVEMaxSupportedInterleaveFactor >= 4))
That should hopefully make it more futureproof, and specifically rule out reverse loads even if the vectorizer changes to support them.


================
Comment at: llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp:1644-1645
+              replaceSymbolicStrideSCEV(PSE, llvm::ValueToValueMap(), Ptr);
+          const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(PtrScev);
+          if (AR) {
+            const SCEV *Step = AR->getStepRecurrence(*PSE.getSE());
----------------
Perhaps
  if (auto AR = dyn_cast<SCEVAddRecExpr>(PtrScev)) {


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D85410/new/

https://reviews.llvm.org/D85410