[TTI][LV] preferPredicateOverEpilogue
We have two ways to steer creating a predicated vector body over creating a
scalar epilogue. To force this, we have 1) a command line option and 2) a
pragma available. This adds a third: a target hook to TargetTransformInfo that
can be queried whether predication is preferred or not, which allows the
vectoriser to make the decision without forcing it.
While this change behaves as a non-functional change for now, it shows the
required TTI plumbing, usage of this new hook in the vectoriser, and the
beginning of an ARM MVE implementation. I will follow up on this with:
- a complete MVE implementation, see D69845.
- a patch to disable this, i.e. we should respect "vector_predicate(disable)"
and its corresponding loophint.
Differential Revision: https://reviews.llvm.org/D69040
diff --git a/llvm/lib/Analysis/TargetTransformInfo.cpp b/llvm/lib/Analysis/TargetTransformInfo.cpp
index ba89a9e..0b40984 100644
--- a/llvm/lib/Analysis/TargetTransformInfo.cpp
+++ b/llvm/lib/Analysis/TargetTransformInfo.cpp
@@ -243,6 +243,12 @@
return TTIImpl->isHardwareLoopProfitable(L, SE, AC, LibInfo, HWLoopInfo);
}
+bool TargetTransformInfo::preferPredicateOverEpilogue(Loop *L, LoopInfo *LI,
+ ScalarEvolution &SE, AssumptionCache &AC, TargetLibraryInfo *TLI,
+ DominatorTree *DT, const LoopAccessInfo *LAI) const {
+ return TTIImpl->preferPredicateOverEpilogue(L, LI, SE, AC, TLI, DT, LAI);
+}
+
void TargetTransformInfo::getUnrollingPreferences(
Loop *L, ScalarEvolution &SE, UnrollingPreferences &UP) const {
return TTIImpl->getUnrollingPreferences(L, SE, UP);