Guard lifetime dependence diagnostics

by -enable-experimental-feature NonescapableTypes

These passes do nothing unless the above feature flag is enabled, so
there's no reason to be running them.

These passes rely on fundamental SwiftCompilerSources abstractions
which have not yet been tested outside of the passes. They don't yet
handle all SIL patterns, and SIL continues to evolve. We should not
expose these issues on a release branch.

This reverts commit 6efcb59.
"Always-enable lifetime-depenence diagnostics."

Workaround for:

** rdar://129931868 [nonescapable] (Crash on attempt to compile unit
   test); SIL/FunctionConvention.swift:29: Fatal error: requires
   contextual type

** rdar://129494573 [nonescapable] [LifetimeDependenceDiagnostics]

** rdar://128434000 ([nonescapable] [LifetimeDependenceInsertion] Package resolution fails with arm64 Windows toolchain)

Author: atrick

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/LifetimeDependenceDiagnostics.swift

@@ -29,6 +29,9 @@ private func log(prefix: Bool = true, _ message: @autoclosure () -> String) {
 let lifetimeDependenceDiagnosticsPass = FunctionPass(
   name: "lifetime-dependence-diagnostics")
 { (function: Function, context: FunctionPassContext) in
+  if !context.options.hasFeature(.NonescapableTypes) {
+    return
+  }
   log(prefix: false, "\n--- Diagnosing lifetime dependence in \(function.name)")
   log("\(function)")
 

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/LifetimeDependenceInsertion.swift

@@ -31,6 +31,9 @@ private func log(prefix: Bool = true, _ message: @autoclosure () -> String) {
 let lifetimeDependenceInsertionPass = FunctionPass(
   name: "lifetime-dependence-insertion")
 { (function: Function, context: FunctionPassContext) in
+  if !context.options.hasFeature(.NonescapableTypes) {
+    return
+  }
   log(prefix: false, "\n--- Inserting lifetime dependence markers in \(function.name)")
 
   for instruction in function.instructions {

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/LifetimeDependenceScopeFixup.swift

@@ -31,6 +31,9 @@ private func log(prefix: Bool = true, _ message: @autoclosure () -> String) {
 let lifetimeDependenceScopeFixupPass = FunctionPass(
   name: "lifetime-dependence-scope-fixup")
 { (function: Function, context: FunctionPassContext) in
+  if !context.options.hasFeature(.NonescapableTypes) {
+    return
+  }
   log(prefix: false, "\n--- Scope fixup for lifetime dependence in \(function.name)")
 
   let localReachabilityCache = LocalVariableReachabilityCache()