RequirementMachine: Right-hand side simplification produces more aesthetically-pleasing 3-cells

Author: slavapestov

lib/AST/RequirementMachine/RewriteSystem.cpp

@@ -345,28 +345,26 @@ void RewriteSystem::simplifyRewriteSystem() {
     assert(oldRuleID == ruleID);
     (void) oldRuleID;
 
-    // Produce a loop at the simplified rhs.
+    // Produce a loop at the original lhs.
     RewritePath loop;
 
-    // (1) First, apply rhsPath in reverse to produce the original rhs.
-    rhsPath.invert();
+    // (1) First, apply the original rule to produce the original rhs.
+    loop.add(RewriteStep::forRewriteRule(/*startOffset=*/0, /*endOffset=*/0,
+                                         ruleID, /*inverse=*/false));
+
+    // (2) Next, apply rhsPath to produce the simplified rhs.
     loop.append(rhsPath);
 
-    // (2) Next, apply the original rule in reverse to produce the
-    // original lhs.
+    // (3) Finally, apply the new rule in reverse to produce the original lhs.
     loop.add(RewriteStep::forRewriteRule(/*startOffset=*/0, /*endOffset=*/0,
-                                         ruleID, /*inverse=*/true));
+                                         newRuleID, /*inverse=*/true));
 
-    // (3) Finally, apply the new rule to produce the simplified rhs.
-    loop.add(RewriteStep::forRewriteRule(/*startOffset=*/0, /*endOffset=*/0,
-                                         newRuleID, /*inverse=*/false));
+    HomotopyGenerators.emplace_back(MutableTerm(lhs), loop);
 
     if (Debug.contains(DebugFlags::Completion)) {
       llvm::dbgs() << "$ Right hand side simplification recorded a loop: ";
-      loop.dump(llvm::dbgs(), rhs, *this);
+      HomotopyGenerators.back().dump(llvm::dbgs(), *this);
     }
-
-    HomotopyGenerators.emplace_back(rhs, loop);
   }
 }