Merge pull request swiftlang#33725 from gottesmm/pr-9d3036face5e432d0ac446965da3a4de0b7b84aa

[semantic-arc] Extract out borrow scope optimizations into its own file.

Author: gottesmm

lib/SILOptimizer/SemanticARC/BorrowScopeOpts.cpp

@@ -0,0 +1,58 @@
+//===--- BorrowScopeOpts.cpp ----------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+///
+/// Optimizations that attempt to simplify and or eliminate borrow scopes. Today
+/// we only eliminate scopes, but we could also eliminate redundant scopes by
+/// converting struct_extract operations to use destructure operations.
+///
+//===----------------------------------------------------------------------===//
+
+#include "SemanticARCOptVisitor.h"
+
+using namespace swift;
+using namespace swift::semanticarc;
+
+bool SemanticARCOptVisitor::visitBeginBorrowInst(BeginBorrowInst *bbi) {
+  auto kind = bbi->getOperand().getOwnershipKind();
+  SmallVector<EndBorrowInst *, 16> endBorrows;
+  for (auto *op : bbi->getUses()) {
+    if (!op->isConsumingUse()) {
+      // Make sure that this operand can accept our arguments kind.
+      auto map = op->getOwnershipKindMap();
+      if (map.canAcceptKind(kind))
+        continue;
+      return false;
+    }
+
+    // Otherwise, this borrow is being consumed. See if our consuming inst is an
+    // end_borrow. If it isn't, then return false, this scope is
+    // needed. Otherwise, add the end_borrow to our list of end borrows.
+    auto *ebi = dyn_cast<EndBorrowInst>(op->getUser());
+    if (!ebi) {
+      return false;
+    }
+    endBorrows.push_back(ebi);
+  }
+
+  // At this point, we know that the begin_borrow's operand can be
+  // used as an argument to all non-end borrow uses. Eliminate the
+  // begin borrow and end borrows.
+  while (!endBorrows.empty()) {
+    auto *ebi = endBorrows.pop_back_val();
+    eraseInstruction(ebi);
+  }
+
+  eraseAndRAUWSingleValueInstruction(bbi, bbi->getOperand());
+  return true;
+}

lib/SILOptimizer/SemanticARC/CMakeLists.txt

@@ -1,4 +1,5 @@
 target_sources(swiftSILOptimizer PRIVATE
   SemanticARCOpts.cpp
   OwnershipLiveRange.cpp
-  LoadCopyToLoadBorrowOpt.cpp)
+  LoadCopyToLoadBorrowOpt.cpp
+  BorrowScopeOpts.cpp)

lib/SILOptimizer/SemanticARC/SemanticARCOpts.cpp

@@ -376,44 +376,6 @@ bool SemanticARCOptVisitor::processWorklist() {
   return madeChange;
 }
 
-//===----------------------------------------------------------------------===//
-//                     Redundant Borrow Scope Elimination
-//===----------------------------------------------------------------------===//
-
-bool SemanticARCOptVisitor::visitBeginBorrowInst(BeginBorrowInst *bbi) {
-  auto kind = bbi->getOperand().getOwnershipKind();
-  SmallVector<EndBorrowInst *, 16> endBorrows;
-  for (auto *op : bbi->getUses()) {
-    if (!op->isConsumingUse()) {
-      // Make sure that this operand can accept our arguments kind.
-      auto map = op->getOwnershipKindMap();
-      if (map.canAcceptKind(kind))
-        continue;
-      return false;
-    }
-
-    // Otherwise, this borrow is being consumed. See if our consuming inst is an
-    // end_borrow. If it isn't, then return false, this scope is
-    // needed. Otherwise, add the end_borrow to our list of end borrows.
-    auto *ebi = dyn_cast<EndBorrowInst>(op->getUser());
-    if (!ebi) {
-      return false;
-    }
-    endBorrows.push_back(ebi);
-  }
-
-  // At this point, we know that the begin_borrow's operand can be
-  // used as an argument to all non-end borrow uses. Eliminate the
-  // begin borrow and end borrows.
-  while (!endBorrows.empty()) {
-    auto *ebi = endBorrows.pop_back_val();
-    eraseInstruction(ebi);
-  }
-
-  eraseAndRAUWSingleValueInstruction(bbi, bbi->getOperand());
-  return true;
-}
-
 //===----------------------------------------------------------------------===//
 //                    CopyValue Optimizations Elimination
 //===----------------------------------------------------------------------===//