[VPlan] Add VPlan-based addMinIterCheck, replace ILV for non-epilogue. (#153643)

This patch adds a new VPlan-based addMinimumIterationCheck, which
replaced the ILV version for the non-epilogue case.

The VPlan-based version constructs a SCEV expression to compute the
minimum iterations, use that to check if the check is known true or
false. Otherwise it creates a VPExpandSCEV recipe and emits a
compare-and-branch.

When using epilogue vectorization, we still need to create the minimum
trip-count-check during the legacy skeleton creation. The patch moves
the definitions out of ILV.

PR: https://github.com/llvm/llvm-project/pull/153643

1 files changed, 3 insertions, 2 deletions

diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index f60a1e9..13b9aa2 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -500,10 +500,11 @@ const SCEV *ScalarEvolution::getVScale(Type *Ty) {
   return S;
 }
 
-const SCEV *ScalarEvolution::getElementCount(Type *Ty, ElementCount EC) {
+const SCEV *ScalarEvolution::getElementCount(Type *Ty, ElementCount EC,
+                                             SCEV::NoWrapFlags Flags) {
   const SCEV *Res = getConstant(Ty, EC.getKnownMinValue());
   if (EC.isScalable())
-    Res = getMulExpr(Res, getVScale(Ty));
+    Res = getMulExpr(Res, getVScale(Ty), Flags);
   return Res;
 }