[region-isolation] Refactor RegionAnalysis AST pattern matching onto a helper factory method on IsolationRegionInfo.

Long term I would like to get region analysis and transfer non sendable out of
the business of directly interpreting the AST... but if we have to do it now, I
would rather us do it through a helper struct. At least the helper struct can be
modified later to work with additional SIL concurrency support when it is added.

Author: gottesmm

include/swift/SILOptimizer/Utils/PartitionUtils.h

@@ -257,6 +257,9 @@ class IsolationRegionInfo {
     return {Kind::Task, value};
   }
 
+  /// Attempt to infer the isolation region info for \p inst.
+  static IsolationRegionInfo get(SILInstruction *inst);
+
   bool operator==(const IsolationRegionInfo &other) const {
     if (getKind() != other.getKind())
       return false;

lib/SILOptimizer/Analysis/RegionAnalysis.cpp

@@ -48,25 +48,6 @@ using namespace swift::regionanalysisimpl;
 //                              MARK: Utilities
 //===----------------------------------------------------------------------===//
 
-/// SILApplyCrossesIsolation determines if a SIL instruction is an isolation
-/// crossing apply expression. This is done by checking its correspondence to an
-/// ApplyExpr AST node, and then checking the internal flags of that AST node to
-/// see if the ActorIsolationChecker determined it crossed isolation.  It's
-/// possible this is brittle and a more nuanced check is needed, but this
-/// suffices for all cases tested so far.
-static bool isIsolationBoundaryCrossingApply(SILInstruction *inst) {
-  if (ApplyExpr *apply = inst->getLoc().getAsASTNode<ApplyExpr>())
-    return apply->getIsolationCrossing().has_value();
-  if (auto fas = FullApplySite::isa(inst)) {
-    if (bool(fas.getIsolationCrossing()))
-      return true;
-  }
-
-  // We assume that any instruction that does not correspond to an ApplyExpr
-  // cannot cross an isolation domain.
-  return false;
-}
-
 namespace {
 
 struct UnderlyingTrackedValueInfo {
@@ -1776,8 +1757,6 @@ class PartitionOpTranslator {
   }
 
   void translateSILPartialApply(PartialApplyInst *pai) {
-    assert(!isIsolationBoundaryCrossingApply(pai));
-
     // First check if our partial apply is Sendable. In such a case, we will
     // have emitted an earlier warning in Sema.
     //
@@ -1811,12 +1790,8 @@ class PartitionOpTranslator {
       }
     }
 
-    if (auto *ace = pai->getLoc().getAsASTNode<AbstractClosureExpr>()) {
-      auto actorIsolation = ace->getActorIsolation();
-      if (actorIsolation.isActorIsolated()) {
-        return translateIsolatedPartialApply(
-            pai, IsolationRegionInfo::getActorIsolated(actorIsolation));
-      }
+    if (auto isolationRegionInfo = IsolationRegionInfo::get(pai)) {
+      return translateIsolatedPartialApply(pai, isolationRegionInfo);
     }
 
     SmallVector<SILValue, 8> applyResults;
@@ -1928,9 +1903,11 @@ class PartitionOpTranslator {
       }
     }
 
+    auto isolationRegionInfo = IsolationRegionInfo::get(inst);
+
     // If this apply does not cross isolation domains, it has normal
     // non-transferring multi-assignment semantics
-    if (!isIsolationBoundaryCrossingApply(inst))
+    if (!bool(isolationRegionInfo))
       return translateNonIsolationCrossingSILApply(fas);
 
     if (auto cast = dyn_cast<ApplyInst>(inst))

lib/SILOptimizer/Utils/PartitionUtils.cpp

@@ -11,8 +11,12 @@
 //===----------------------------------------------------------------------===//
 
 #include "swift/SILOptimizer/Utils/PartitionUtils.h"
+#include "swift/AST/Expr.h"
+#include "swift/SIL/ApplySite.h"
 #include "llvm/Support/CommandLine.h"
 
+using namespace swift;
+
 //===----------------------------------------------------------------------===//
 //                               MARK: Logging
 //===----------------------------------------------------------------------===//
@@ -31,3 +35,33 @@ static llvm::cl::opt<bool, true> // The parser
                                REGIONBASEDISOLATION_ENABLE_VERBOSE_LOGGING));
 
 #endif
+
+//===----------------------------------------------------------------------===//
+//                         MARK: IsolationRegionInfo
+//===----------------------------------------------------------------------===//
+
+IsolationRegionInfo IsolationRegionInfo::get(SILInstruction *inst) {
+  if (ApplyExpr *apply = inst->getLoc().getAsASTNode<ApplyExpr>())
+    if (auto crossing = apply->getIsolationCrossing())
+      return IsolationRegionInfo::getActorIsolated(
+          crossing->getCalleeIsolation());
+
+  if (auto fas = FullApplySite::isa(inst)) {
+    if (auto crossing = fas.getIsolationCrossing())
+      return IsolationRegionInfo::getActorIsolated(
+          crossing->getCalleeIsolation());
+  }
+
+  if (auto *pai = dyn_cast<PartialApplyInst>(inst)) {
+    if (auto *ace = pai->getLoc().getAsASTNode<AbstractClosureExpr>()) {
+      auto actorIsolation = ace->getActorIsolation();
+      if (actorIsolation.isActorIsolated()) {
+        return IsolationRegionInfo::getActorIsolated(actorIsolation);
+      }
+    }
+  }
+
+  // We assume that any instruction that does not correspond to an ApplyExpr
+  // cannot cross an isolation domain.
+  return IsolationRegionInfo();
+}