Bug 1399471 part 1 - Disable the full_debug_checks jit pref by default in browser builds. r=nbp

js/src/jit/CodeGenerator.cpp

@@ -5159,6 +5159,7 @@ CodeGenerator::emitAssertObjectOrStringResult(Register input, MIRType type, cons
     }
 
     // Check that we have a valid GC pointer.
+    if (JitOptions.fullDebugChecks) {
         saveVolatile();
         masm.setupUnalignedABICall(temp);
         masm.loadJSContext(temp);
@@ -5185,6 +5186,7 @@ CodeGenerator::emitAssertObjectOrStringResult(Register input, MIRType type, cons
 
         masm.callWithABI(callee);
         restoreVolatile();
+    }
 
     masm.bind(&done);
     masm.pop(temp);
@@ -5228,6 +5230,7 @@ CodeGenerator::emitAssertResultV(const ValueOperand input, const TemporaryTypeSe
     }
 
     // Check that we have a valid GC pointer.
+    if (JitOptions.fullDebugChecks) {
         saveVolatile();
 
         masm.pushValue(input);
@@ -5240,6 +5243,7 @@ CodeGenerator::emitAssertResultV(const ValueOperand input, const TemporaryTypeSe
         masm.callWithABI(JS_FUNC_TO_DATA_PTR(void*, AssertValidValue));
         masm.popValue(input);
         restoreVolatile();
+    }
 
     masm.bind(&done);
     masm.pop(temp2);
@@ -5466,10 +5470,8 @@ CodeGenerator::generateBody()
                 extendTrackedOptimizationsEntry(iter->mirRaw()->trackedOptimizations());
 
 #ifdef DEBUG
-            if (!counts) {
-                if (JitOptions.fullDebugChecks)
+            if (!counts)
                 emitDebugResultChecks(*iter);
-            }
 #endif
         }
         if (masm.oom())

modules/libpref/init/all.js

@@ -1437,7 +1437,7 @@ pref("javascript.options.asyncstack",       false);
 pref("javascript.options.throw_on_asmjs_validation_failure", false);
 pref("javascript.options.ion.offthread_compilation", true);
 #ifdef DEBUG
-pref("javascript.options.jit.full_debug_checks", true);
+pref("javascript.options.jit.full_debug_checks", false);
 #endif
 // This preference instructs the JS engine to discard the
 // source of any privileged JS after compilation. This saves