[NFC] Add a utility for this load take/borrow dance

Author: rjmccall

lib/SILGen/RValue.cpp

@@ -94,12 +94,8 @@ class ExplodeTupleValue
 
   void visitType(CanType formalType, ManagedValue v) {
     // If we have a loadable type that has not been loaded, actually load it.
-    if (!v.getType().isObject() && v.getType().isLoadable(SGF.F)) {
-      if (v.isPlusOne(SGF)) {
-        v = SGF.B.createLoadTake(loc, v);
-      } else {
-        v = SGF.B.createLoadBorrow(loc, v);
-      }
+    if (!v.getType().isObject()) {
+      v = SGF.B.createLoadIfLoadable(loc, v);
     }
 
     values.push_back(v);

lib/SILGen/SILGenBuilder.cpp

@@ -437,6 +437,23 @@ ManagedValue SILGenBuilder::createUncheckedTakeEnumDataAddr(
   return cloner.clone(result);
 }
 
+ManagedValue
+SILGenBuilder::createLoadIfLoadable(SILLocation loc, ManagedValue addr) {
+  assert(addr.getType().isAddress());
+  if (!addr.getType().isLoadable(SGF.F))
+    return addr;
+  return createLoadWithSameOwnership(loc, addr);
+}
+
+ManagedValue
+SILGenBuilder::createLoadWithSameOwnership(SILLocation loc,
+                                           ManagedValue addr) {
+  if (addr.isPlusOne(SGF))
+    return createLoadTake(loc, addr);
+  else
+    return createLoadBorrow(loc, addr);
+}
+
 ManagedValue SILGenBuilder::createLoadTake(SILLocation loc, ManagedValue v) {
   auto &lowering = SGF.getTypeLowering(v.getType());
   return createLoadTake(loc, v, lowering);

lib/SILGen/SILGenBuilder.h

@@ -236,6 +236,15 @@ class SILGenBuilder : public SILBuilder {
   ManagedValue createUncheckedTakeEnumDataAddr(SILLocation loc, ManagedValue operand,
                                                EnumElementDecl *element, SILType ty);
 
+  /// Given the address of a value, load a scalar value from it if the type
+  /// is loadable.  Most general routines in SILGen expect to work with
+  /// values with the canonical scalar-ness for their type.
+  ManagedValue createLoadIfLoadable(SILLocation loc, ManagedValue addr);
+
+  /// Given the address of a loadable value, load the value but don't
+  /// change the ownership.
+  ManagedValue createLoadWithSameOwnership(SILLocation loc, ManagedValue addr);
+
   ManagedValue createLoadTake(SILLocation loc, ManagedValue addr);
   ManagedValue createLoadTake(SILLocation loc, ManagedValue addr,
                               const TypeLowering &lowering);

lib/SILGen/SILGenProlog.cpp

@@ -263,10 +263,7 @@ class EmitBBArguments : public CanTypeVisitor<EmitBBArguments,
     bool argIsLoadable = argType.isLoadable(SGF.F);
     if (argIsLoadable) {
       if (argType.isAddress()) {
-        if (mv.isPlusOne(SGF))
-          mv = SGF.B.createLoadTake(loc, mv);
-        else
-          mv = SGF.B.createLoadBorrow(loc, mv);
+        mv = SGF.B.createLoadWithSameOwnership(loc, mv);
         argType = argType.getObjectType();
       }
     }