Merge pull request #21231 from DougGregor/simd-operator-type-check-perf-hack

[Constraint solver] De-prioritize SIMD operators.

Author: DougGregor

lib/Sema/CSStep.cpp

@@ -490,6 +490,27 @@ bool DisjunctionStep::shouldStopAt(const DisjunctionChoice &choice) const {
           shortCircuitDisjunctionAt(choice, lastChoice));
 }
 
+bool swift::isSIMDOperator(ValueDecl *value) {
+  if (!value)
+    return false;
+
+  auto func = dyn_cast<FuncDecl>(value);
+  if (!func)
+    return false;
+
+  if (!func->isOperator())
+    return false;
+
+  auto nominal = func->getDeclContext()->getSelfNominalTypeDecl();
+  if (!nominal)
+    return false;
+
+  if (nominal->getName().empty())
+    return false;
+
+  return nominal->getName().str().startswith_lower("simd");
+}
+
 bool DisjunctionStep::shortCircuitDisjunctionAt(
     Constraint *currentChoice, Constraint *lastSuccessfulChoice) const {
   auto &ctx = CS.getASTContext();
@@ -535,6 +556,16 @@ bool DisjunctionStep::shortCircuitDisjunctionAt(
   if (currentChoice->getKind() == ConstraintKind::CheckedCast)
     return true;
 
+  // If we have an operator from the SIMDOperators module, and the prior
+  // choice was not from the SIMDOperators module, we're done.
+  if (currentChoice->getKind() == ConstraintKind::BindOverload &&
+      isSIMDOperator(currentChoice->getOverloadChoice().getDecl()) &&
+      lastSuccessfulChoice->getKind() == ConstraintKind::BindOverload &&
+      !isSIMDOperator(lastSuccessfulChoice->getOverloadChoice().getDecl()) &&
+      !ctx.LangOpts.SolverEnableOperatorDesignatedTypes) {
+    return true;
+  }
+
   return false;
 }
 

lib/Sema/ConstraintSystem.cpp

@@ -1443,6 +1443,40 @@ static void tryOptimizeGenericDisjunction(ConstraintSystem &cs,
   }
 }
 
+/// If there are any SIMD operators in the overload set, partition the set so
+/// that the SIMD operators come at the end.
+static ArrayRef<OverloadChoice> partitionSIMDOperators(
+                                  ArrayRef<OverloadChoice> choices,
+                                  SmallVectorImpl<OverloadChoice> &scratch) {
+  // If the first element isn't an operator, none of them are.
+  if (!choices[0].isDecl() ||
+      !isa<FuncDecl>(choices[0].getDecl()) ||
+      !cast<FuncDecl>(choices[0].getDecl())->isOperator() ||
+      choices[0].getDecl()->getASTContext().LangOpts
+        .SolverEnableOperatorDesignatedTypes)
+    return choices;
+
+  // Check whether we have any SIMD operators.
+  bool foundSIMDOperator = false;
+  for (const auto &choice : choices) {
+    if (isSIMDOperator(choice.getDecl())) {
+      foundSIMDOperator = true;
+      break;
+    }
+  }
+
+  if (!foundSIMDOperator)
+    return choices;
+
+  scratch.assign(choices.begin(), choices.end());
+  std::stable_partition(scratch.begin(), scratch.end(),
+                        [](const OverloadChoice &choice) {
+                          return !isSIMDOperator(choice.getDecl());
+                        });
+
+  return scratch;
+}
+
 void ConstraintSystem::addOverloadSet(Type boundType,
                                       ArrayRef<OverloadChoice> choices,
                                       DeclContext *useDC,
@@ -1459,6 +1493,9 @@ void ConstraintSystem::addOverloadSet(Type boundType,
 
   tryOptimizeGenericDisjunction(*this, choices, favoredChoice);
 
+  SmallVector<OverloadChoice, 4> scratchChoices;
+  choices = partitionSIMDOperators(choices, scratchChoices);
+
   SmallVector<Constraint *, 4> overloads;
 
   // As we do for other favored constraints, if a favored overload has been

lib/Sema/ConstraintSystem.h

@@ -3829,6 +3829,9 @@ bool exprNeedsParensOutsideFollowingOperator(
     TypeChecker &TC, DeclContext *DC, Expr *expr, Expr *rootExpr,
     PrecedenceGroupDecl *followingPG);
 
+/// Determine whether this is a SIMD operator.
+bool isSIMDOperator(ValueDecl *value);
+
 } // end namespace swift
 
 #endif // LLVM_SWIFT_SEMA_CONSTRAINT_SYSTEM_H

validation-test/Sema/type_checker_perf/fast/rdar46541800.swift

@@ -0,0 +1,62 @@
+// RUN: %target-typecheck-verify-swift
+// RUN: %target-typecheck-verify-swift -solver-enable-operator-designated-types
+// REQUIRES: OS=macosx
+
+import simd
+import CoreGraphics
+import Foundation
+
+class SomeView {
+  func layoutSubviews() {
+    let descriptionTextViewFrame = CGRect.zero
+    let availableBounds = CGRect()
+    let descriptionLabelProperties = SomeView.descriptionTextViewLabelProperties()
+    let textSize = descriptionTextView.sizeThatFits(availableBounds.size)
+    let textInset = descriptionTextView.textInset(forBounds: CGRect(origin: .zero, size: textSize))
+    let descriptionTextBaselineOffset: CGFloat = CGFloat()
+    let displayScale: CGFloat = CGFloat()
+    let _ = (descriptionTextViewFrame.height 
+             + (-descriptionTextView.lastBaselineOffsetFromBottom - textInset.bottom + descriptionLabelProperties.lastBaselineOffsetFromBottom)
+            + (-descriptionTextView.firstBaselineOffsetFromTop - textInset.top + descriptionTextBaselineOffset).ceilingValue(scale: displayScale)
+            )
+  }
+
+  static func descriptionTextViewLabelProperties() -> FontDescriptorBaselineProperties {
+      fatalError()
+  }
+  
+  lazy var descriptionTextView: SomeOtherView = SomeOtherView()
+}
+
+class SomeOtherView {
+  init() { }
+  func sizeThatFits(_ size: CGSize) -> CGSize { return size }
+}
+
+
+struct FontDescriptorBaselineProperties {
+ //   let fontDescriptor: MPUFontDescriptor
+    let defaultFirstBaselineOffsetFromTop: CGFloat
+    let defaultLastBaselineOffsetFromBottom: CGFloat
+    var firstBaselineOffsetFromTop: CGFloat { fatalError() }    
+    var lastBaselineOffsetFromBottom: CGFloat {
+        fatalError()
+    }
+}
+
+struct EdgeInsets {
+  var top: CGFloat
+  var bottom: CGFloat
+}
+
+extension SomeOtherView {
+    func textInset(forBounds bounds: CGRect) -> EdgeInsets { fatalError() }
+    var firstBaselineOffsetFromTop: CGFloat { fatalError() }    
+    var lastBaselineOffsetFromBottom: CGFloat {
+        fatalError()
+    }
+}
+
+extension CGFloat {
+    public func ceilingValue(scale: CGFloat) -> CGFloat { fatalError() }
+}