Fix use of MemAcessUtils in LICM (#38784)

AccessPathWithBase::compute can return a valid access path with unidentified base.
In such cases, we cannot LICM stores, because there is no base address to check if it is invariant

Author: meg-gupta

lib/SIL/Utils/MemAccessUtils.cpp

@@ -1015,7 +1015,8 @@ LLVM_ATTRIBUTE_USED void AccessPath::dump() const { print(llvm::dbgs()); }
 void AccessPathWithBase::print(raw_ostream &os) const {
   if (base)
     os << "Base: " << base;
-
+  else
+    os << "Base: unidentified\n";
   accessPath.print(os);
 }
 

lib/SILOptimizer/LoopTransforms/LICM.cpp

@@ -939,7 +939,8 @@ void LoopTreeOptimization::analyzeCurrentLoop(
     // how to rematerialize global_addr, then we don't need this base.
     auto access = AccessPathWithBase::compute(SI->getDest());
     auto accessPath = access.accessPath;
-    if (accessPath.isValid() && isLoopInvariant(access.base, Loop)) {
+    if (accessPath.isValid() &&
+        (access.base && isLoopInvariant(access.base, Loop))) {
       if (isOnlyLoadedAndStored(AA, sideEffects, Loads, Stores, SI->getDest(),
                                 accessPath)) {
         if (!LoadAndStoreAddrs.count(accessPath)) {

test/SILOptimizer/licm.sil

@@ -1318,3 +1318,82 @@ bb3:
   %outer = tuple (%extract0 : $Int64, %inner: $(Int64, Int64))
   return %outer : $(Int64, (Int64, Int64))
 }
+
+class C {}
+
+// This won't be hoisted because we can't find a base to check if it is invariant
+// CHECK-LABEL: sil @testLoopInvariantStoreNoBase1 :
+// CHECK: bb6:
+// CHECK-NOT:   store
+// CHECK-LABEL: } // end sil function 'testLoopInvariantStoreNoBase1'
+sil @testLoopInvariantStoreNoBase1 : $@convention(thin) (Builtin.BridgeObject, Double) -> () {
+bb0(%0 : $Builtin.BridgeObject, %1 : $Double):
+  cond_br undef, bb1, bb2
+
+bb1:
+  %2 = unchecked_ref_cast %0 : $Builtin.BridgeObject to $C
+  %3 = ref_tail_addr [immutable] %2 : $C, $Double
+  %4 = address_to_pointer %3 : $*Double to $Builtin.RawPointer
+  br bb3(%4 : $Builtin.RawPointer)
+
+bb2:
+  %6 = unchecked_ref_cast %0 : $Builtin.BridgeObject to $C
+  %7 = ref_tail_addr [immutable] %6 : $C, $Double
+  %8 = address_to_pointer %7 : $*Double to $Builtin.RawPointer
+  br bb3(%8 : $Builtin.RawPointer)
+
+bb3(%9 : $Builtin.RawPointer):
+  br bb4
+
+bb4:
+  %11 = pointer_to_address %9 : $Builtin.RawPointer to [strict] $*Double
+  store %1 to %11 : $*Double
+  cond_br undef, bb5, bb6
+
+bb5:
+  br bb4
+
+bb6:
+  %15 = tuple ()
+  return %15 : $()
+}
+
+// This won't be hoisted because we can't find a base to check if it is invariant
+// CHECK-LABEL: sil @testLoopInvariantStoreNoBase2 :
+// CHECK: bb6:
+// CHECK-NOT:   store
+// CHECK-LABEL: } // end sil function 'testLoopInvariantStoreNoBase2'
+sil @testLoopInvariantStoreNoBase2 : $@convention(thin) (Builtin.BridgeObject, Double) -> () {
+bb0(%0 : $Builtin.BridgeObject, %1 : $Double):
+  cond_br undef, bb1, bb2
+
+bb1:
+  %2 = unchecked_ref_cast %0 : $Builtin.BridgeObject to $C
+  %3 = ref_tail_addr [immutable] %2 : $C, $Double
+  %4 = address_to_pointer %3 : $*Double to $Builtin.RawPointer
+  br bb3(%4 : $Builtin.RawPointer)
+
+bb2:
+  %6 = unchecked_ref_cast %0 : $Builtin.BridgeObject to $C
+  %7 = ref_tail_addr [immutable] %6 : $C, $Double
+  %8 = address_to_pointer %7 : $*Double to $Builtin.RawPointer
+  br bb3(%8 : $Builtin.RawPointer)
+
+bb3(%9 : $Builtin.RawPointer):
+  br bb4
+
+bb4:
+  %11 = pointer_to_address %9 : $Builtin.RawPointer to [strict] $*Double
+  %12 = integer_literal $Builtin.Word, 1
+  %13 = index_addr %11 : $*Double, %12 : $Builtin.Word
+  store %1 to %13 : $*Double
+  cond_br undef, bb5, bb6
+
+bb5:
+  br bb4
+
+bb6:
+  %15 = tuple ()
+  return %15 : $()
+}
+