[move-only] Move move function kills values checking and move only value lifetime checking before diagnostic constant prop.

This is part of a larger piece of work that is going to introduce the ability in
SIL for us to wrap trivial values in a move only type wrapper and thus perform
ownership based diagnostics upon those trivial values. This is being done now so
that we can perform SSA based ownership diagnostics on trivial types. This will
allow us to eventually be able to do things like no escape analysis on
UnsafePointer.

That all sounds great, but also we must consider how this effects the rest of
the optimizer. For instance, what if we want to have a no escape integer and
have overflow checks used upon it! To ensure that we can do this, the authors
realized that we did not need to persist the ownership information so late in
that part of the pipeline and we can just do the ownership checking earlier than
constant propagation and then lower. This is safe to do since the rest of the
optimizer will not introduce escapes of a pointer or extra copies unlike if the
underlying non move only type variant was also non-trivial.

With that in hand, this PR moves these two move only passes earlier than
constant propagation for this purpose. The reason they were put in the current
position vs earlier is that I wanted them to run after predictable dead
allocation elimination since it cleaned up the SIL I was reading as I designed
it. There isn't any reason that they can't run earlier. Once I bring in the new
SIL move only type wrapper, after these run, the trivial type lowering will then
run.

Author: gottesmm

lib/SILOptimizer/PassManager/PassPipeline.cpp

@@ -157,6 +157,12 @@ static void addMandatoryDiagnosticOptPipeline(SILPassPipelinePlan &P) {
   // SSA based diagnostics.
   P.addPredictableMemoryAccessOptimizations();
 
+  // Now that we have promoted simple loads for SSA based diagnostics, perform
+  // SSA based move function checking and no implicit copy checking.
+  P.addMoveKillsCopyableValuesChecker(); // No uses after _move of copyable
+                                         //   value.
+  P.addMoveOnlyChecker();                // Check noImplicitCopy isn't copied.
+
   // This phase performs optimizations necessary for correct interoperation of
   // Swift os log APIs with C os_log ABIs.
   // Pass dependencies: this pass depends on MandatoryInlining and Mandatory
@@ -173,11 +179,6 @@ static void addMandatoryDiagnosticOptPipeline(SILPassPipelinePlan &P) {
   // dead allocations.
   P.addPredictableDeadAllocationElimination();
 
-  // Now perform move semantic checking.
-  P.addMoveKillsCopyableValuesChecker(); // No uses after _move of copyable
-                                         //   value.
-  P.addMoveOnlyChecker();                // Check noImplicitCopy isn't copied.
-
   // Now that we have finished performing diagnostics that rely on lexical
   // scopes, if lexical lifetimes are not enabled, eliminate lexical lfietimes.
   if (Options.LexicalLifetimes != LexicalLifetimesOption::On) {