MandatoryPerformanceOptimizations: use eliminateRedundantLoads instead of optimizeMemoryAccesses to optimize redundant loads

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/ModulePasses/MandatoryPerformanceOptimizations.swift

@@ -159,6 +159,14 @@ private func optimize(function: Function, _ context: FunctionPassContext, _ modu
         {
           fri.referencedFunction.set(linkage: .public, moduleContext)
         }
+        
+      case let copy as CopyAddrInst:
+        if function.isGlobalInitOnceFunction, copy.source.type.isLoadable(in: function) {
+          // In global init functions we have to make sure that redundant load elimination can remove all
+          // loads (from temporary stack locations) so that globals can be statically initialized.
+          // For this it's necessary to load copy_addr instructions to loads and stores.
+          copy.replaceWithLoadAndStore(simplifyCtxt)
+        }
 
       default:
         break
@@ -170,7 +178,13 @@ private func optimize(function: Function, _ context: FunctionPassContext, _ modu
     removeUnusedMetatypeInstructions(in: function, context)
 
     // If this is a just specialized function, try to optimize copy_addr, etc.
-    changed = context.optimizeMemoryAccesses(in: function) || changed
+    if eliminateRedundantLoads(in: function,
+                               variant: function.isGlobalInitOnceFunction ? .mandatoryInGlobalInit : .mandatory,
+                               context)
+    {
+      changed = true
+    }
+
     changed = context.eliminateDeadAllocations(in: function) || changed
   }
 }

SwiftCompilerSources/Sources/Optimizer/PassManager/Context.swift

@@ -346,14 +346,6 @@ struct FunctionPassContext : MutatingContext {
     _bridged.asNotificationHandler().notifyChanges(.effectsChanged)
   }
 
-  func optimizeMemoryAccesses(in function: Function) -> Bool {
-    if _bridged.optimizeMemoryAccesses(function.bridged) {
-      notifyInstructionsChanged()
-      return true
-    }
-    return false
-  }
-
   func eliminateDeadAllocations(in function: Function) -> Bool {
     if _bridged.eliminateDeadAllocations(function.bridged) {
       notifyInstructionsChanged()

include/swift/SILOptimizer/OptimizerBridging.h

@@ -259,7 +259,6 @@ struct BridgedPassContext {
                                                             BridgedLinkage linkage, bool isLet) const;
   void inlineFunction(BridgedInstruction apply, bool mandatoryInline) const;
   SWIFT_IMPORT_UNSAFE BRIDGED_INLINE BridgedValue getSILUndef(BridgedType type) const;
-  BRIDGED_INLINE bool optimizeMemoryAccesses(BridgedFunction f) const;
   BRIDGED_INLINE bool eliminateDeadAllocations(BridgedFunction f) const;
 
   BRIDGED_INLINE bool shouldExpand(BridgedType type) const;

include/swift/SILOptimizer/OptimizerBridgingImpl.h

@@ -260,9 +260,6 @@ BridgedValue BridgedPassContext::getSILUndef(BridgedType type) const {
   return {swift::SILUndef::get(invocation->getFunction(), type.unbridged())};
 }
 
-bool BridgedPassContext::optimizeMemoryAccesses(BridgedFunction f) const {
-  return swift::optimizeMemoryAccesses(f.getFunction());
-}
 bool BridgedPassContext::eliminateDeadAllocations(BridgedFunction f) const {
   return swift::eliminateDeadAllocations(f.getFunction(),
                                          this->getDomTree().di);