Bug 1805337 - Remove use of increment on volatile data r=sfink

This removes a custom version of AutoSuppressGCAnalysis that wasn't really
needed and replaces increment with assignment in gbd-tests.cpp.

Differential Revision: https://phabricator.services.mozilla.com/D164576

js/src/gdb/gdb-tests.cpp

@@ -23,7 +23,7 @@ static const JSClass global_class = {"global", JSCLASS_GLOBAL_FLAGS,
 
 static volatile int dontOptimizeMeAway = 0;
 
-void usePointer(const void* ptr) { dontOptimizeMeAway++; }
+void usePointer(const void* ptr) { dontOptimizeMeAway = 1; }
 
 template <typename T>
 static inline T* checkPtr(T* ptr) {

js/src/gdb/gdb-tests.h

@@ -33,15 +33,6 @@ void use(const T& thing) {
   usePointer(&thing);
 }
 
-struct AutoSuppressHazardsForTest {
-  int dummy;
-  AutoSuppressHazardsForTest() : dummy(3) {}
-  ~AutoSuppressHazardsForTest() {
-    // Need nontrivial destructor.
-    usePointer(&dummy);
-  }
-} JS_HAZ_GC_SUPPRESSED;
-
 struct GDBFragment {
   GDBFragment() {
     next = allFragments;

js/src/gdb/tests/test-JSObject.cpp

@@ -4,8 +4,6 @@
 #include "js/Object.h"  // JS::GetClass
 
 FRAGMENT(JSObject, simple) {
-  AutoSuppressHazardsForTest noanalysis;
-
   JS::Rooted<JSObject*> glob(cx, JS::CurrentGlobalOrNull(cx));
   JS::Rooted<JSObject*> plain(cx, JS_NewPlainObject(cx));
   JS::Rooted<JSObject*> objectProto(cx, JS::GetRealmObjectPrototype(cx));
@@ -17,18 +15,19 @@ FRAGMENT(JSObject, simple) {
   JS::Rooted<JSFunction*> funcPtr(
       cx, JS_NewFunction(cx, (JSNative)1, 0, 0, "formFollows"));
 
-  JSObject& plainRef = *plain;
-  JSFunction& funcRef = *funcPtr;
-  JSObject* plainRaw = plain;
-  JSObject* funcRaw = func;
-
   // JS_NewObject will now assert if you feed it a bad class name, so mangle
   // the name after construction.
   char namebuf[20] = "goodname";
   static JSClass cls{namebuf};
   JS::RootedObject badClassName(cx, JS_NewObject(cx, &cls));
+  MOZ_RELEASE_ASSERT(badClassName);
   strcpy(namebuf, "\xc7X");
 
+  JSObject& plainRef = *plain;
+  JSFunction& funcRef = *funcPtr;
+  JSObject* plainRaw = plain;
+  JSObject* funcRaw = func;
+
   breakpoint();
 
   use(glob);

js/src/gdb/tests/test-JSString.cpp

@@ -6,8 +6,6 @@
 #include "vm/StringType.h"
 
 FRAGMENT(JSString, simple) {
-  AutoSuppressHazardsForTest noanalysis;
-
   JS::Rooted<JSString*> empty(cx, JS_NewStringCopyN(cx, nullptr, 0));
   JS::Rooted<JSString*> x(cx, JS_NewStringCopyN(cx, "x", 1));
   JS::Rooted<JSString*> z(cx, JS_NewStringCopyZ(cx, "z"));
@@ -41,8 +39,6 @@ FRAGMENT(JSString, simple) {
 }
 
 FRAGMENT(JSString, null) {
-  AutoSuppressHazardsForTest noanalysis;
-
   JS::Rooted<JSString*> null(cx, nullptr);
   JSString* nullRaw = null;
 

js/src/jsapi-tests/testGCStoreBufferRemoval.cpp

@@ -6,18 +6,14 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "gc/Barrier.h"
+#include "js/GCAPI.h"
 #include "jsapi-tests/tests.h"
 
 using namespace JS;
 using namespace js;
 
-struct AutoIgnoreRootingHazards {
-  // Force a nontrivial destructor so the compiler sees the whole RAII scope
-  static volatile int depth;
-  AutoIgnoreRootingHazards() { depth++; }
-  ~AutoIgnoreRootingHazards() { depth--; }
-} JS_HAZ_GC_SUPPRESSED;
-volatile int AutoIgnoreRootingHazards::depth = 0;
+// Name this constant without creating a GC hazard.
+#define BAD_OBJECT_PTR reinterpret_cast<JSObject*>(1)
 
 BEGIN_TEST(testGCStoreBufferRemoval) {
   // Sanity check - objects start in the nursery and then become tenured.
@@ -28,33 +24,29 @@ BEGIN_TEST(testGCStoreBufferRemoval) {
   CHECK(!js::gc::IsInsideNursery(obj.get()));
   JS::RootedObject tenuredObject(cx, obj);
 
-  // Hide the horrors herein from the static rooting analysis.
-  AutoIgnoreRootingHazards ignore;
-
   // Test removal of store buffer entries added by HeapPtr<T>.
   {
-    JSObject* badObject = reinterpret_cast<JSObject*>(1);
     JSObject* punnedPtr = nullptr;
     HeapPtr<JSObject*>* relocPtr =
         reinterpret_cast<HeapPtr<JSObject*>*>(&punnedPtr);
     new (relocPtr) HeapPtr<JSObject*>;
     *relocPtr = NurseryObject();
     relocPtr->~HeapPtr<JSObject*>();
-    punnedPtr = badObject;
+    punnedPtr = BAD_OBJECT_PTR;
     JS_GC(cx);
 
     new (relocPtr) HeapPtr<JSObject*>;
     *relocPtr = NurseryObject();
     *relocPtr = tenuredObject;
     relocPtr->~HeapPtr<JSObject*>();
-    punnedPtr = badObject;
+    punnedPtr = BAD_OBJECT_PTR;
     JS_GC(cx);
 
     new (relocPtr) HeapPtr<JSObject*>;
     *relocPtr = NurseryObject();
     *relocPtr = nullptr;
     relocPtr->~HeapPtr<JSObject*>();
-    punnedPtr = badObject;
+    punnedPtr = BAD_OBJECT_PTR;
     JS_GC(cx);
   }
 
@@ -86,27 +78,26 @@ BEGIN_TEST(testGCStoreBufferRemoval) {
 
   // Test removal of store buffer entries added by Heap<T>.
   {
-    JSObject* badObject = reinterpret_cast<JSObject*>(1);
     JSObject* punnedPtr = nullptr;
     Heap<JSObject*>* heapPtr = reinterpret_cast<Heap<JSObject*>*>(&punnedPtr);
     new (heapPtr) Heap<JSObject*>;
     *heapPtr = NurseryObject();
     heapPtr->~Heap<JSObject*>();
-    punnedPtr = badObject;
+    punnedPtr = BAD_OBJECT_PTR;
     JS_GC(cx);
 
     new (heapPtr) Heap<JSObject*>;
     *heapPtr = NurseryObject();
     *heapPtr = tenuredObject;
     heapPtr->~Heap<JSObject*>();
-    punnedPtr = badObject;
+    punnedPtr = BAD_OBJECT_PTR;
     JS_GC(cx);
 
     new (heapPtr) Heap<JSObject*>;
     *heapPtr = NurseryObject();
     *heapPtr = nullptr;
     heapPtr->~Heap<JSObject*>();
-    punnedPtr = badObject;
+    punnedPtr = BAD_OBJECT_PTR;
     JS_GC(cx);
   }
 
@@ -115,3 +106,5 @@ BEGIN_TEST(testGCStoreBufferRemoval) {
 
 JSObject* NurseryObject() { return JS_NewPlainObject(cx); }
 END_TEST(testGCStoreBufferRemoval)
+
+#undef BAD_OBJECT_PTR