[Profiler] NFC: Rename assignCounter -> assignKnownCounter

Make it clearer that we expect an existing counter
to have been assigned by MapRegionCounters.

Author: hamishknight

lib/SIL/IR/SILProfiler.cpp

@@ -757,8 +757,9 @@ struct CoverageMapping : public ASTWalker {
       Res.first->second = std::move(Expr);
   }
 
-  /// Create a counter expression referencing \c Node's own counter.
-  CounterExpr assignCounter(ASTNode Node) {
+  /// Create a counter expression referencing \c Node's own counter. This must
+  /// have been previously mapped by MapRegionCounters.
+  CounterExpr assignKnownCounter(ASTNode Node) {
     auto Counter = CounterExpr::Leaf(Node);
     assignCounter(Node, Counter);
     return Counter;
@@ -966,10 +967,10 @@ struct CoverageMapping : public ASTWalker {
   PreWalkAction walkToDeclPre(Decl *D) override {
     if (auto *AFD = dyn_cast<AbstractFunctionDecl>(D)) {
       return visitFunctionDecl(*this, AFD, [&] {
-        assignCounter(AFD->getBody());
+        assignKnownCounter(AFD->getBody());
       });
     } else if (auto *TLCD = dyn_cast<TopLevelCodeDecl>(D)) {
-      assignCounter(TLCD->getBody());
+      assignKnownCounter(TLCD->getBody());
       ImplicitTopLevelBody = TLCD->getBody();
       return Action::Continue();
     }
@@ -1005,15 +1006,15 @@ struct CoverageMapping : public ASTWalker {
 
       // We emit a counter for the then block, and define the else block in
       // terms of it.
-      auto ThenCounter = assignCounter(IS->getThenStmt());
+      auto ThenCounter = assignKnownCounter(IS->getThenStmt());
       if (IS->getElseStmt()) {
         auto ElseCounter =
             CounterExpr::Sub(getCurrentCounter(), ThenCounter, CounterAlloc);
         assignCounter(IS->getElseStmt(), ElseCounter);
       }
     } else if (auto *GS = dyn_cast<GuardStmt>(S)) {
       assignCounter(GS, CounterExpr::Zero());
-      assignCounter(GS->getBody());
+      assignKnownCounter(GS->getBody());
 
     } else if (auto *WS = dyn_cast<WhileStmt>(S)) {
       // The counter for the while statement itself tracks the number of jumps
@@ -1022,22 +1023,22 @@ struct CoverageMapping : public ASTWalker {
 
       if (auto *E = getConditionNode(WS->getCond()))
         assignCounter(E, getCurrentCounter());
-      assignCounter(WS->getBody());
+      assignKnownCounter(WS->getBody());
 
     } else if (auto *RWS = dyn_cast<RepeatWhileStmt>(S)) {
       // The counter for the while statement itself tracks the number of jumps
       // to it by break and continue statements.
       assignCounter(RWS, CounterExpr::Zero());
 
-      auto BodyCounter = assignCounter(RWS->getBody());
+      auto BodyCounter = assignKnownCounter(RWS->getBody());
       assignCounter(RWS->getCond(), BodyCounter);
       RepeatWhileStack.push_back(RWS);
 
     } else if (auto *FES = dyn_cast<ForEachStmt>(S)) {
       // The counter for the for statement itself tracks the number of jumps
       // to it by break and continue statements.
       assignCounter(FES, CounterExpr::Zero());
-      assignCounter(FES->getBody());
+      assignKnownCounter(FES->getBody());
 
     } else if (auto *SS = dyn_cast<SwitchStmt>(S)) {
       // The counter for the switch statement itself tracks the number of jumps
@@ -1049,7 +1050,7 @@ struct CoverageMapping : public ASTWalker {
 
       // Assign counters for cases so they're available for fallthrough.
       for (CaseStmt *Case : SS->getCases())
-        assignCounter(Case);
+        assignKnownCounter(Case);
 
     } else if (auto caseStmt = dyn_cast<CaseStmt>(S)) {
       if (caseStmt->getParentKind() == CaseParentKind::Switch)
@@ -1066,7 +1067,7 @@ struct CoverageMapping : public ASTWalker {
       assignCounter(DCS->getBody(), getCurrentCounter());
 
       for (CaseStmt *Catch : DCS->getCatches())
-        assignCounter(Catch->getBody());
+        assignKnownCounter(Catch->getBody());
 
       // Initialize the exit count of the do-catch to the entry count, then
       // subtract off non-local exits as they are visited.
@@ -1183,19 +1184,19 @@ struct CoverageMapping : public ASTWalker {
     if (Parent.isNull()) {
       assert(RegionStack.empty() &&
              "Mapped a region before visiting the root?");
-      assignCounter(E);
+      assignKnownCounter(E);
     }
 
     if (isa<LazyInitializerExpr>(E))
-      assignCounter(E);
+      assignKnownCounter(E);
 
     if (hasCounter(E))
       pushRegion(E);
 
     assert(!RegionStack.empty() && "Must be within a region");
 
     if (auto *IE = dyn_cast<TernaryExpr>(E)) {
-      auto ThenCounter = assignCounter(IE->getThenExpr());
+      auto ThenCounter = assignKnownCounter(IE->getThenExpr());
       auto ElseCounter =
           CounterExpr::Sub(getCurrentCounter(), ThenCounter, CounterAlloc);
       assignCounter(IE->getElseExpr(), ElseCounter);