Merge pull request #41557 from atrick/addrlower-update

Update and reimplement AddressLowering pass (for SIL opaque values).

Author: atrick

docs/SIL.rst

@@ -2193,6 +2193,26 @@ parts::
        return %1 : $Klass
      }
 
+Forwarding Address-Only Values
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Address-only values are potentially unmovable when borrowed. This
+means that they cannot be forwarded with guaranteed ownership unless
+the forwarded value has the same representation as in the original
+value and can reuse the same storage. Non-destructive projection is
+allowed, such as `struct_extract`. Aggregation, such as `struct`, and
+destructive disaggregation, such as `switch_enum` is not allowed. This
+is an invariant for OSSA with opaque SIL values for these reasons:
+
+1. To avoid implicit semantic copies. For move-only values, this allows
+complete diagnostics. And in general, it makes it impossible for SIL
+passes to "accidentally" create copies.
+
+2. To reuse borrowed storage. This allows the optimizer to share the same
+storage for multiple exclusive reads of the same variable, avoiding
+copies. It may also be necessary to support native Swift atomics, which
+will be unmovable-when-borrowed.
+
 Borrowed Object based Safe Interior Pointers
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

include/swift/AST/SILOptions.h

@@ -140,6 +140,9 @@ class SILOptions {
   /// If this is disabled we do not serialize in OSSA form when optimizing.
   bool EnableOSSAModules = false;
 
+  /// If set to true, compile with the SIL Opaque Values enabled.
+  bool EnableSILOpaqueValues = false;
+
   // The kind of function bodies to skip emitting.
   FunctionBodySkipping SkipFunctionBodies = FunctionBodySkipping::None;
 

include/swift/Basic/LangOptions.h

@@ -379,11 +379,6 @@ namespace swift {
     /// [TODO: Clang-type-plumbing] Turn on for feature rollout.
     bool UseClangFunctionTypes = false;
 
-    /// If set to true, compile with the SIL Opaque Values enabled.
-    /// This is for bootstrapping. It can't be in SILOptions because the
-    /// TypeChecker uses it to set resolve the ParameterConvention.
-    bool EnableSILOpaqueValues = false;
-
     /// If set to true, the diagnosis engine can assume the emitted diagnostics
     /// will be used in editor. This usually leads to more aggressive fixit.
     bool DiagnosticsEditorMode = false;

include/swift/Option/FrontendOptions.td

@@ -507,9 +507,6 @@ def disable_sil_ownership_verifier : Flag<["-"], "disable-sil-ownership-verifier
 def suppress_static_exclusivity_swap : Flag<["-"], "suppress-static-exclusivity-swap">,
   HelpText<"Suppress static violations of exclusive access with swap()">;
 
-def enable_sil_opaque_values : Flag<["-"], "enable-sil-opaque-values">,
-  HelpText<"Enable SIL Opaque Values">;
-  
 def enable_experimental_static_assert :
   Flag<["-"], "enable-experimental-static-assert">,
   HelpText<"Enable experimental #assert">;
@@ -1022,6 +1019,9 @@ def enable_ossa_modules : Flag<["-"], "enable-ossa-modules">,
   HelpText<"Always serialize SIL in ossa form. If this flag is not passed in, "
            "when optimizing ownership will be lowered before serializing SIL">;
 
+def enable_sil_opaque_values : Flag<["-"], "enable-sil-opaque-values">,
+  HelpText<"Enable SIL Opaque Values">;
+
 def new_driver_path
   : Separate<["-"], "new-driver-path">, MetaVarName<"<path>">,
   HelpText<"Path of the new driver to be used">;

include/swift/SIL/ApplySite.h

@@ -585,9 +585,9 @@ class FullApplySite : public ApplySite {
   }
 
   /// Get the SIL value that represents all of the given call's results. For a
-  /// single direct result, returns the result. For multiple results, returns a
-  /// fake tuple value. The tuple has no storage of its own. The real results
-  /// must be extracted from it.
+  /// single direct result, returns the actual result. For multiple results,
+  /// returns a pseudo-result tuple. The tuple has no storage of its own. The
+  /// real results must be extracted from it.
   ///
   /// For ApplyInst, returns the single-value instruction itself.
   ///
@@ -596,7 +596,7 @@ class FullApplySite : public ApplySite {
   /// For BeginApplyInst, returns an invalid value. For coroutines, there is no
   /// single value representing all results. Yielded values are generally
   /// handled differently since they have the convention of incoming arguments.
-  SILValue getPseudoResult() const {
+  SILValue getResult() const {
     switch (getKind()) {
     case FullApplySiteKind::ApplyInst:
       return SILValue(cast<ApplyInst>(getInstruction()));

include/swift/SIL/SILBuilder.h

@@ -266,11 +266,10 @@ class SILBuilder {
   void clearInsertionPoint() { BB = nullptr; }
 
   /// setInsertionPoint - Set the insertion point.
-  void setInsertionPoint(SILBasicBlock *BB, SILBasicBlock::iterator InsertPt) {
+  void setInsertionPoint(SILBasicBlock *BB, SILBasicBlock::iterator insertPt) {
     this->BB = BB;
-    this->InsertPt = InsertPt;
-    if (InsertPt == BB->end())
-      return;
+    this->InsertPt = insertPt;
+    assert(insertPt == BB->end() || insertPt->getParent() == BB);
   }
 
   /// setInsertionPoint - Set the insertion point to insert before the specified

include/swift/SIL/SILModule.h

@@ -307,6 +307,12 @@ class SILModule {
   /// The stage of processing this module is at.
   SILStage Stage;
 
+  /// True if SIL conventions force address-only to be passed by address.
+  ///
+  /// Used for bootstrapping the AddressLowering pass. This should eventually
+  /// be inferred from the SIL stage to be true only when Stage == Lowered.
+  bool loweredAddresses;
+
   /// The set of deserialization notification handlers.
   DeserializationNotificationHandlerSet deserializationNotificationHandlers;
 
@@ -806,6 +812,11 @@ class SILModule {
     Stage = s;
   }
 
+  /// True if SIL conventions force address-only to be passed by address.
+  bool useLoweredAddresses() const { return loweredAddresses; }
+
+  void setLoweredAddresses(bool val) { loweredAddresses = val; }
+
   llvm::IndexedInstrProfReader *getPGOReader() const { return PGOReader.get(); }
 
   void setPGOReader(std::unique_ptr<llvm::IndexedInstrProfReader> IPR) {
@@ -972,15 +983,13 @@ inline bool SILOptions::supportsLexicalLifetimes(const SILModule &mod) const {
     // entirely.
     return LexicalLifetimes != LexicalLifetimesOption::Off;
   case SILStage::Canonical:
+  case SILStage::Lowered:
     // In Canonical SIL, lexical markers are used to ensure that object
     // lifetimes do not get observably shortened from the end of a lexical
     // scope.  That behavior only occurs when lexical lifetimes is (fully)
     // enabled.  (When only diagnostic markers are enabled, the markers are
     // stripped as part of lowering from raw to canonical SIL.)
     return LexicalLifetimes == LexicalLifetimesOption::On;
-  case SILStage::Lowered:
-    // We do not support OSSA in Lowered SIL, so this is always false.
-    return false;
   }
 }
 

lib/Frontend/CompilerInvocation.cpp

@@ -770,7 +770,6 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
   Opts.EnableObjCInterop =
       Args.hasFlag(OPT_enable_objc_interop, OPT_disable_objc_interop,
                    Target.isOSDarwin());
-  Opts.EnableSILOpaqueValues |= Args.hasArg(OPT_enable_sil_opaque_values);
 
   Opts.VerifyAllSubstitutionMaps |= Args.hasArg(OPT_verify_all_substitution_maps);
 
@@ -1678,6 +1677,7 @@ static bool ParseSILArgs(SILOptions &Opts, ArgList &Args,
   Opts.EnableARCOptimizations &= !Args.hasArg(OPT_disable_arc_opts);
   Opts.EnableOSSAModules |= Args.hasArg(OPT_enable_ossa_modules);
   Opts.EnableOSSAOptimizations &= !Args.hasArg(OPT_disable_ossa_opts);
+  Opts.EnableSILOpaqueValues |= Args.hasArg(OPT_enable_sil_opaque_values);
   Opts.EnableSpeculativeDevirtualization |= Args.hasArg(OPT_enable_spec_devirt);
   Opts.EnableActorDataRaceChecks |= Args.hasFlag(
       OPT_enable_actor_data_race_checks,

lib/SIL/IR/SILModule.cpp

@@ -91,8 +91,8 @@ class SILModule::SerializationCallback final
 
 SILModule::SILModule(llvm::PointerUnion<FileUnit *, ModuleDecl *> context,
                      Lowering::TypeConverter &TC, const SILOptions &Options)
-    : Stage(SILStage::Raw), indexTrieRoot(new IndexTrieNode()),
-      Options(Options), serialized(false),
+    : Stage(SILStage::Raw), loweredAddresses(!Options.EnableSILOpaqueValues),
+      indexTrieRoot(new IndexTrieNode()), Options(Options), serialized(false),
       regDeserializationNotificationHandlerForNonTransparentFuncOME(false),
       regDeserializationNotificationHandlerForAllFuncOME(false),
       prespecializedFunctionDeclsImported(false), SerializeSILAction(),

lib/SIL/IR/SILType.cpp

@@ -506,10 +506,7 @@ SILResultInfo::getOwnershipKind(SILFunction &F,
 }
 
 SILModuleConventions::SILModuleConventions(SILModule &M)
-    : M(&M),
-      loweredAddresses(!M.getASTContext().LangOpts.EnableSILOpaqueValues
-                       || M.getStage() == SILStage::Lowered)
-{}
+    : M(&M), loweredAddresses(M.useLoweredAddresses()) {}
 
 bool SILModuleConventions::isReturnedIndirectlyInSIL(SILType type,
                                                      SILModule &M) {