Bug 1700771 - Create pref for inlining maximum function size. r=iain

Differential Revision: https://phabricator.services.mozilla.com/D110350

js/src/jsapi.cpp

@@ -5283,6 +5283,13 @@ JS_PUBLIC_API void JS_SetGlobalJitCompilerOption(JSContext* cx,
         JitSpew(js::jit::JitSpew_IonScripts, "Disable offthread compilation");
       }
       break;
+    case JSJITCOMPILER_INLINING_BYTECODE_MAX_LENGTH:
+      if (value == uint32_t(-1)) {
+        jit::DefaultJitOptions defaultValues;
+        value = defaultValues.smallFunctionMaxBytecodeLength;
+      }
+      jit::JitOptions.smallFunctionMaxBytecodeLength = value;
+      break;
     case JSJITCOMPILER_JUMP_THRESHOLD:
       if (value == uint32_t(-1)) {
         jit::DefaultJitOptions defaultValues;
@@ -5364,6 +5371,9 @@ JS_PUBLIC_API bool JS_GetGlobalJitCompilerOption(JSContext* cx,
     case JSJITCOMPILER_ION_FREQUENT_BAILOUT_THRESHOLD:
       *valueOut = jit::JitOptions.frequentBailoutThreshold;
       break;
+    case JSJITCOMPILER_INLINING_BYTECODE_MAX_LENGTH:
+      *valueOut = jit::JitOptions.smallFunctionMaxBytecodeLength;
+      break;
     case JSJITCOMPILER_BASELINE_INTERPRETER_ENABLE:
       *valueOut = jit::JitOptions.baselineInterpreter;
       break;

js/src/jsapi.h

@@ -2632,6 +2632,7 @@ extern JS_PUBLIC_API void JS_SetOffthreadIonCompilationEnabled(JSContext* cx,
   Register(JIT_TRUSTEDPRINCIPALS_ENABLE, "jit_trustedprincipals.enable") \
   Register(ION_CHECK_RANGE_ANALYSIS, "ion.check-range-analysis") \
   Register(ION_FREQUENT_BAILOUT_THRESHOLD, "ion.frequent-bailout-threshold") \
+  Register(INLINING_BYTECODE_MAX_LENGTH, "inlining.bytecode-max-length") \
   Register(BASELINE_INTERPRETER_ENABLE, "blinterp.enable") \
   Register(BASELINE_ENABLE, "baseline.enable") \
   Register(OFFTHREAD_COMPILATION_ENABLE, "offthread-compilation.enable")  \

js/xpconnect/src/XPCJSContext.cpp

@@ -885,6 +885,10 @@ static void LoadStartupJSPrefs(XPCJSContext* xpccx) {
       cx, JSJITCOMPILER_ION_FREQUENT_BAILOUT_THRESHOLD,
       StaticPrefs::
           javascript_options_ion_frequent_bailout_threshold_DoNotUseDirectly());
+  JS_SetGlobalJitCompilerOption(
+      cx, JSJITCOMPILER_INLINING_BYTECODE_MAX_LENGTH,
+      StaticPrefs::
+          javascript_options_inlining_bytecode_max_length_DoNotUseDirectly());
 
 #ifdef DEBUG
   JS_SetGlobalJitCompilerOption(

modules/libpref/init/StaticPrefList.yaml

@@ -5454,6 +5454,17 @@
   mirror: always  # LoadStartupJSPrefs
   do_not_use_directly: true
 
+# A threshold for Warp to decide whether a function can be inlined.
+# If the size of a function is smaller than this threshold, then it
+# may be inlined. 
+#
+# NOTE: These must match JitOptions defaults.
+- name: javascript.options.inlining_bytecode_max_length
+  type: uint32_t
+  value: 130
+  mirror: always
+  do_not_use_directly: true
+
 - name: javascript.options.compact_on_user_inactive
   type: bool
   value: true