Bug 1677354 - Part 2: Assert all non-top-level scripts are function. …

…r=tcampbell Differential Revision: https://phabricator.services.mozilla.com/D97112
dothq · Dec 12, 2020 · 0712077 · 0712077
1 parent 8cb2349
commit 0712077
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Showing 2 changed files with 22 additions and 10 deletions.
diff --git a/js/src/frontend/CompilationInfo.h b/js/src/frontend/CompilationInfo.h
@@ -343,19 +343,19 @@ class ScriptStencilIterable {
     Iterator(const CompilationStencil& stencil, CompilationGCOutput& gcOutput,
              size_t index)
         : index_(index), stencil_(stencil), gcOutput_(gcOutput) {
-      skipNonFunctions();
+      MOZ_ASSERT(index == stencil.scriptData.length());
     }
 
    public:
     explicit Iterator(const CompilationStencil& stencil,
                       CompilationGCOutput& gcOutput)
         : stencil_(stencil), gcOutput_(gcOutput) {
-      skipNonFunctions();
+      skipTopLevelNonFunction();
     }
 
     Iterator operator++() {
       next();
-      skipNonFunctions();
+      assertFunction();
       return *this;
     }
 
@@ -364,14 +364,19 @@ class ScriptStencilIterable {
       index_++;
     }
 
-    void skipNonFunctions() {
-      size_t length = stencil_.scriptData.length();
-      while (index_ < length) {
-        if (stencil_.scriptData[index_].isFunction()) {
-          return;
-        }
+    void assertFunction() {
+      if (index_ < stencil_.scriptData.length()) {
+        MOZ_ASSERT(stencil_.scriptData[index_].isFunction());
+      }
+    }
 
-        index_++;
+    void skipTopLevelNonFunction() {
+      MOZ_ASSERT(index_ == 0);
+      if (stencil_.scriptData.length()) {
+        if (!stencil_.scriptData[0].isFunction()) {
+          next();
+          assertFunction();
+        }
       }
     }
 

diff --git a/js/src/jit-test/tests/parser/optimized-out-functions.js b/js/src/jit-test/tests/parser/optimized-out-functions.js
@@ -0,0 +1,7 @@
+// Functions optimized out by constant-folding should have correct
+// stencil data.
+// This shouldn't hit any assertion while iterating stencil while instantiation.
+(function() {
+  (function() {
+  });
+});