RequirementMachine: Verify loops immediately when they're added to aid debugging

Author: slavapestov

lib/AST/RequirementMachine/HomotopyReduction.cpp

@@ -475,9 +475,6 @@ void RewriteSystem::minimizeRewriteSystem() {
   assert(!Minimized);
   Minimized = 1;
 
-  // Check invariants before homotopy reduction.
-  verifyRewriteLoops();
-
   propagateExplicitBits();
 
   // First pass:
@@ -623,24 +620,7 @@ RewriteSystem::getMinimizedGenericSignatureRules() const {
 void RewriteSystem::verifyRewriteLoops() const {
 #ifndef NDEBUG
   for (const auto &loop : Loops) {
-    RewritePathEvaluator evaluator(loop.Basepoint);
-
-    for (const auto &step : loop.Path) {
-      evaluator.apply(step, *this);
-    }
-
-    if (evaluator.getCurrentTerm() != loop.Basepoint) {
-      llvm::errs() << "Not a loop: ";
-      loop.dump(llvm::errs(), *this);
-      llvm::errs() << "\n";
-      abort();
-    }
-
-    if (evaluator.isInContext()) {
-      llvm::errs() << "Leftover terms on evaluator stack\n";
-      evaluator.dump(llvm::errs());
-      abort();
-    }
+    loop.verify(*this);
   }
 #endif
 }

lib/AST/RequirementMachine/RewriteLoop.cpp

@@ -109,6 +109,29 @@ void RewritePath::dump(llvm::raw_ostream &out,
   }
 }
 
+void RewriteLoop::verify(const RewriteSystem &system) const {
+#ifndef NDEBUG
+  RewritePathEvaluator evaluator(Basepoint);
+
+  for (const auto &step : Path) {
+    evaluator.apply(step, system);
+  }
+
+  if (evaluator.getCurrentTerm() != Basepoint) {
+    llvm::errs() << "Not a loop: ";
+    dump(llvm::errs(), system);
+    llvm::errs() << "\n";
+    abort();
+  }
+
+  if (evaluator.isInContext()) {
+    llvm::errs() << "Leftover terms on evaluator stack\n";
+    evaluator.dump(llvm::errs());
+    abort();
+  }
+#endif
+}
+
 void RewriteLoop::dump(llvm::raw_ostream &out,
                        const RewriteSystem &system) const {
   out << Basepoint << ": ";

lib/AST/RequirementMachine/RewriteLoop.h

@@ -286,6 +286,8 @@ class RewriteLoop {
                           ProtocolConformanceRules, 2> &result,
       const RewriteSystem &system) const;
 
+  void verify(const RewriteSystem &system) const;
+
   void dump(llvm::raw_ostream &out, const RewriteSystem &system) const;
 };
 

lib/AST/RequirementMachine/RewriteSystem.cpp

@@ -628,14 +628,17 @@ bool RewriteSystem::isInMinimizationDomain(
 
 void RewriteSystem::recordRewriteLoop(MutableTerm basepoint,
                                       RewritePath path) {
+  RewriteLoop loop(basepoint, path);
+  loop.verify(*this);
+
   if (!RecordLoops)
     return;
 
   // Ignore the rewrite rule if it is not part of our minimization domain.
   if (!isInMinimizationDomain(basepoint.getRootProtocols()))
     return;
 
-  Loops.emplace_back(basepoint, path);
+  Loops.push_back(loop);
 }
 
 void RewriteSystem::verifyRewriteRules(ValidityPolicy policy) const {