1 files changed, 32 insertions, 0 deletions
diff --git a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
index be14a832265..77ca4c6b087 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
@@ -626,6 +626,38 @@ bool AArch64TTIImpl::getTgtMemIntrinsic(IntrinsicInst *Inst,
   return true;
 }
 
+/// See if \p I should be considered for address type promotion. We check if \p
+/// I is a sext with right type and used in memory accesses. If it used in a
+/// "complex" getelementptr, we allow it to be promoted without finding other
+/// sext instructions that sign extended the same initial value. A getelementptr
+/// is considered as "complex" if it has more than 2 operands.
+bool AArch64TTIImpl::shouldConsiderAddressTypePromotion(
+    const Instruction &I, bool &AllowPromotionWithoutCommonHeader) {
+  bool Considerable = false;
+  AllowPromotionWithoutCommonHeader = false;
+  if (!isa<SExtInst>(&I))
+    return false;
+  Type *ConsideredSExtType =
+      Type::getInt64Ty(I.getParent()->getParent()->getContext());
+  if (I.getType() != ConsideredSExtType)
+    return false;
+  // See if the sext is the one with the right type and used in at least one
+  // GetElementPtrInst.
+  for (const User *U : I.users()) {
+    if (const GetElementPtrInst *GEPInst = dyn_cast<GetElementPtrInst>(U)) {
+      Considerable = true;
+      // A getelementptr is considered as "complex" if it has more than 2
+      // operands. We will promote a SExt used in such complex GEP as we
+      // expect some computation to be merged if they are done on 64 bits.
+      if (GEPInst->getNumOperands() > 2) {
+        AllowPromotionWithoutCommonHeader = true;
+        break;
+      }
+    }
+  }
+  return Considerable;
+}
+
 unsigned AArch64TTIImpl::getCacheLineSize() {
   return ST->getCacheLineSize();
 }