Merge pull request swiftlang#30307 from hborla/merge-partial-solutions-too-complex

[ConstraintSystem] Respect the constraint solver performance thresholds,

Author: hborla

lib/Sema/CSStep.cpp

@@ -220,6 +220,7 @@ bool SplitterStep::mergePartialSolutions() const {
   ArrayRef<unsigned> counts = countsVec;
   SmallVector<unsigned, 2> indices(numComponents, 0);
   bool anySolutions = false;
+  size_t solutionMemory = 0;
   do {
     // Create a new solver scope in which we apply all of the relevant partial
     // solutions.
@@ -236,13 +237,20 @@ bool SplitterStep::mergePartialSolutions() const {
     if (!CS.worseThanBestSolution()) {
       // Finalize this solution.
       auto solution = CS.finalize();
+      solutionMemory += solution.getTotalMemory();
       if (isDebugMode())
         getDebugLogger() << "(composed solution " << CS.CurrentScore << ")\n";
 
       // Save this solution.
       Solutions.push_back(std::move(solution));
       anySolutions = true;
     }
+
+    // Since merging partial solutions can go exponential, make sure we didn't
+    // pass the "too complex" thresholds including allocated memory and time.
+    if (CS.getExpressionTooComplex(solutionMemory))
+      return false;
+
   } while (nextCombination(counts, indices));
 
   return anySolutions;

lib/Sema/ConstraintSystem.h

@@ -4469,14 +4469,11 @@ class ConstraintSystem {
   /// Determine if we've already explored too many paths in an
   /// attempt to solve this expression.
   bool isExpressionAlreadyTooComplex = false;
-  bool getExpressionTooComplex(SmallVectorImpl<Solution> const &solutions) {
+  bool getExpressionTooComplex(size_t solutionMemory) {
     if (isExpressionAlreadyTooComplex)
       return true;
 
-    auto used = getASTContext().getSolverMemory();
-    for (auto const& s : solutions) {
-      used += s.getTotalMemory();
-    }
+    auto used = getASTContext().getSolverMemory() + solutionMemory;
     MaxMemory = std::max(used, MaxMemory);
     auto threshold = getASTContext().TypeCheckerOpts.SolverMemoryThreshold;
     if (MaxMemory > threshold) {
@@ -4503,6 +4500,14 @@ class ConstraintSystem {
     return false;
   }
 
+  bool getExpressionTooComplex(SmallVectorImpl<Solution> const &solutions) {
+    size_t solutionMemory = 0;
+    for (auto const& s : solutions) {
+      solutionMemory += s.getTotalMemory();
+    }
+    return getExpressionTooComplex(solutionMemory);
+  }
+
   // Utility class that can collect information about the type of an
   // argument in an apply.
   //

validation-test/Sema/type_checker_perf/slow/rdar53589951.swift

@@ -0,0 +1,27 @@
+// RUN: %target-typecheck-verify-swift -solver-expression-time-threshold=1
+// REQUIRES: tools-release,no_asan
+
+class Color {
+  init(hue: Double, saturation: Double, brightness: Double, alpha: Double) {}
+  init(red: Double, green: Double, blue: Double, alpha: Double) {}
+}
+
+// expected-error@+1 {{reasonable time}}
+let _: [Color] = [
+    Color(r: 3, g: 72, b: 14, a: 48),
+    Color(r: 0, g: 240, b: 64, a: 77),
+    Color(r: 0, g: 255, b: 0, a: 160),
+    Color(r: 0, g: 168, b: 0, a: 255),
+    Color(r: 0, g: 140, b: 0, a: 255),
+    Color(r: 0, g: 112, b: 0, a: 255),
+    Color(r: 255, g: 255, b: 0, a: 255),
+    Color(r: 184, g: 184, b: 0, a: 255),
+    Color(r: 224, g: 112, b: 0, a: 255),
+    Color(r: 255, g: 0, b: 0, a: 255),
+    Color(r: 184, g: 0, b: 0, a: 255),
+    Color(r: 112, g: 0, b: 0, a: 255),
+    Color(r: 255, g: 0, b: 255, a: 255),
+    Color(r: 255, g: 0, b: 255, a: 255),
+    Color(r: 255, g: 0, b: 255, a: 255),
+    Color(r: 0, g: 0, b: 0, a: 0),
+]