[gardening] Make a piece of code a little more readable.

Basically the if/else statement of this section of code are unrelated by have
the same condition (albeit inverted). Rather than keep them together and make
them seem as related semantic checks, move the no implicit copy diagnostic into
its own section.

I am doing this as a separate commit partially to slim down the next series of
commits.

Author: gottesmm

lib/SILGen/SILGenProlog.cpp

@@ -109,28 +109,29 @@ class EmitBBArguments : public CanTypeVisitor<EmitBBArguments,
 
     // This can happen if the value is resilient in the calling convention
     // but not resilient locally.
-    if (argType.isLoadable(SGF.F)) {
+    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);
         argType = argType.getObjectType();
       }
-    } else {
-      if (isNoImplicitCopy) {
-        // We do not support no implicit copy address only types. Emit an error.
-        auto diag = diag::noimplicitcopy_used_on_generic_or_existential;
-        diagnose(SGF.getASTContext(), mv.getValue().getLoc().getSourceLoc(),
-                 diag);
-      }
     }
 
     if (argType.getASTType() != paramType.getASTType()) {
       // Reabstract the value if necessary.
       mv = SGF.emitOrigToSubstValue(loc, mv.ensurePlusOne(SGF, loc), orig, t);
     }
 
+    if (isNoImplicitCopy && !argIsLoadable) {
+      // We do not support no implicit copy address only types. Emit an error.
+      auto diag = diag::noimplicitcopy_used_on_generic_or_existential;
+      diagnose(SGF.getASTContext(), mv.getValue().getLoc().getSourceLoc(),
+               diag);
+    }
+
     // If the value is a (possibly optional) ObjC block passed into the entry
     // point of the function, then copy it so we can treat the value reliably
     // as a heap object. Escape analysis can eliminate this copy if it's