[BackwardReachability] Enforce correct API usage.

nate-chandler · nate-chandler · commit 9cc4a97b6b7f · 2022-05-21T12:56:50.000-07:00
diff --git a/include/swift/SILOptimizer/Analysis/Reachability.h b/include/swift/SILOptimizer/Analysis/Reachability.h
@@ -65,6 +65,7 @@ class BackwardReachability {
   SILFunction *function;
   BlockReachability &reachableBlocks;
   BasicBlockWorklist cfgWorklist;
+  bool solved = false;
 
 public:
   BackwardReachability(SILFunction *function,
@@ -74,6 +75,7 @@ class BackwardReachability {
 
   // Initialize data flow starting points before running solveBackward.
   void initLastUse(SILInstruction *lastUsePoint) {
+    assert(!solved && "adding last use after solving!?");
     auto *lastUseBlock = lastUsePoint->getParent();
     auto *previous = lastUsePoint->getPreviousInstruction();
     if (!previous || canReachBlockBegin(previous)) {
@@ -93,6 +95,7 @@ class BackwardReachability {
         pushPreds(block);
       }
     }
+    solved = true;
   }
 
 protected:

Original file line number	Diff line number	Diff line change
`@@ -65,6 +65,7 @@ class BackwardReachability {`
`65`	`65`	`SILFunction *function;`
`66`	`66`	`BlockReachability &reachableBlocks;`
`67`	`67`	`BasicBlockWorklist cfgWorklist;`
	`68`	`+ bool solved = false;`
`68`	`69`
`69`	`70`	`public:`
`70`	`71`	`BackwardReachability(SILFunction *function,`
`@@ -74,6 +75,7 @@ class BackwardReachability {`
`74`	`75`
`75`	`76`	`// Initialize data flow starting points before running solveBackward.`
`76`	`77`	`void initLastUse(SILInstruction *lastUsePoint) {`
	`78`	`+ assert(!solved && "adding last use after solving!?");`
`77`	`79`	`auto *lastUseBlock = lastUsePoint->getParent();`
`78`	`80`	`auto *previous = lastUsePoint->getPreviousInstruction();`
`79`	`81`	`if (!previous \|\| canReachBlockBegin(previous)) {`
`@@ -93,6 +95,7 @@ class BackwardReachability {`
`93`	`95`	`pushPreds(block);`
`94`	`96`	`}`
`95`	`97`	`}`
	`98`	`+ solved = true;`
`96`	`99`	`}`
`97`	`100`
`98`	`101`	`protected:`