Bug 1827914 - Add debug logging around self-hosted JIT code cache r=iain

Differential Revision: https://phabricator.services.mozilla.com/D237812

Author: bthrall

js/src/frontend/Stencil.cpp

@@ -52,6 +52,7 @@
 #include "vm/BindingKind.h"  // BindingKind
 #include "vm/EnvironmentObject.h"
 #include "vm/GeneratorAndAsyncKind.h"  // GeneratorKind, FunctionAsyncKind
+#include "vm/JSAtomUtils.h"            // AtomToPrintableString
 #include "vm/JSContext.h"              // JSContext
 #include "vm/JSFunction.h"  // JSFunction, GetFunctionPrototype, NewFunctionWithProto
 #include "vm/JSObject.h"      // JSObject, TenuredObject
@@ -2945,9 +2946,17 @@ bool CompilationStencil::delazifySelfHostedFunction(
     // JitCode for reuse across the runtime. If the cache already contains an
     // entry for this function, update the JitScript. If not, compile it now and
     // store it in the cache.
+    UniqueChars nameStr;
+    if (JS_SHOULD_LOG(selfHosted, Debug)) {
+      nameStr = AtomToPrintableString(cx, name);
+    }
     auto& jitCache = cx->runtime()->selfHostJitCache.ref();
     auto v = jitCache.readonlyThreadsafeLookup(jitCacheKey);
     if (v && v->value()->method()) {
+      JS_LOG(selfHosted, Debug,
+             "self_hosted_cache: reusing JIT code for script '%s'",
+             nameStr.get());
+
       if (!cx->zone()->ensureJitZoneExists(cx)) {
         return false;
       }
@@ -2973,6 +2982,10 @@ bool CompilationStencil::delazifySelfHostedFunction(
     } else if (jit::IsBaselineJitEnabled(cx) && script->canBaselineCompile() &&
                !script->hasBaselineScript() &&
                jit::CanBaselineInterpretScript(script)) {
+      JS_LOG(selfHosted, Debug,
+             "self_hosted_cache: new JIT code entry for script '%s'",
+             nameStr.get());
+
       if (!cx->zone()->ensureJitZoneExists(cx)) {
         return false;
       }
@@ -2999,6 +3012,11 @@ bool CompilationStencil::delazifySelfHostedFunction(
       if (!jitCache.put(jitCacheKey, baselineScript)) {
         return false;
       }
+    } else {
+      JS_LOG(selfHosted, Debug,
+             "self_hosted_cache: script '%s' is not eligible for Baseline "
+             "compilation",
+             nameStr.get());
     }
   }
 

js/src/vm/Logging.h

@@ -91,6 +91,7 @@ class LogModule {
   _(thenable)             /* Thenable on standard proto*/                    \
   _(startup)              /* engine startup logging */                       \
   _(teleporting)          /* Shape Teleporting */                            \
+  _(selfHosted)           /* self-hosted script logging */                   \
   JITSPEW_CHANNEL_LIST(_) /* A module for each JitSpew channel. */
 
 // Declare Log modules
@@ -106,6 +107,9 @@ FOR_EACH_JS_LOG_MODULE(DECLARE_MODULE);
 
 // The core logging macro for the JS Engine.
 #ifdef JS_LOGGING
+#  define JS_SHOULD_LOG(name, log_level) \
+    name##Module.shouldLog(LogLevel::log_level)
+
 #  define JS_LOG(name, log_level, ...)                                     \
     do {                                                                   \
       if (name##Module.shouldLog(LogLevel::log_level)) {                   \