Bug 1523993: Add JitOptions to disable wasm fast paths; r=luke

This adds a new configure option `--enable-wasm-codegen-debug`, which defaults
to true in debug builds (disable otherwise).

It's a first step so as to be able to use this in both the shell and browser,
using the env variables JIT_OPTION_{JitOption field name}.

Differential Revision: https://phabricator.services.mozilla.com/D18341

--HG--
extra : rebase_source : 37c717f4cc225a9a7d162df3b0312b68e39ad07e

js/moz.configure

@@ -515,3 +515,14 @@ js_option('--enable-cranelift',
 
 set_config('ENABLE_WASM_CRANELIFT', depends_if('--enable-cranelift')(lambda x: True))
 set_define('ENABLE_WASM_CRANELIFT', depends_if('--enable-cranelift')(lambda x: True))
+
+
+# Support for debugging code generated by wasm backends
+# =====================================================
+
+js_option('--enable-wasm-codegen-debug',
+          default=depends(when=moz_debug)(lambda: True),
+          help='{Enable|Disable} debugging for wasm codegen')
+
+set_config('WASM_CODEGEN_DEBUG', depends_if('--enable-wasm-codegen-debug')(lambda x: True))
+set_define('WASM_CODEGEN_DEBUG', depends_if('--enable-wasm-codegen-debug')(lambda x: True))

js/src/jit/JitOptions.cpp

@@ -273,6 +273,12 @@ DefaultJitOptions::DefaultJitOptions() {
   // the traceLogger will not be recording any events.
   SET_DEFAULT(enableTraceLogger, false);
 #endif
+
+#ifdef WASM_CODEGEN_DEBUG
+  SET_DEFAULT(enableWasmJitExit, true);
+  SET_DEFAULT(enableWasmJitEntry, true);
+  SET_DEFAULT(enableWasmIonFastCalls, true);
+#endif
 }
 
 bool DefaultJitOptions::isSmallFunction(JSScript* script) const {

js/src/jit/JitOptions.h

@@ -74,6 +74,11 @@ struct DefaultJitOptions {
   bool wasmDelayTier2;
 #ifdef JS_TRACE_LOGGING
   bool enableTraceLogger;
+#endif
+#ifdef WASM_CODEGEN_DEBUG
+  bool enableWasmJitExit;
+  bool enableWasmJitEntry;
+  bool enableWasmIonFastCalls;
 #endif
   uint32_t baselineWarmUpThreshold;
   uint32_t exceptionBailoutThreshold;

js/src/jit/MCallOptimize.cpp

@@ -4054,7 +4054,12 @@ IonBuilder::InliningResult IonBuilder::inlineWasmCall(CallInfo& callInfo,
   // Check that the function doesn't take or return non-compatible JS
   // argument types before adding nodes to the MIR graph, otherwise they'd be
   // dead code.
-  if (sig.hasI64ArgOrRet() || sig.temporarilyUnsupportedAnyRef()) {
+  if (sig.hasI64ArgOrRet() ||
+      sig.temporarilyUnsupportedAnyRef()
+#ifdef WASM_CODEGEN_DEBUG
+      || !JitOptions.enableWasmIonFastCalls
+#endif
+     ) {
     return InliningStatus_NotInlined;
   }
 

js/src/wasm/WasmInstance.cpp

@@ -154,6 +154,12 @@ bool Instance::callImport(JSContext* cx, uint32_t funcImportIndex,
     return false;
   }
 
+#ifdef WASM_CODEGEN_DEBUG
+  if (!JitOptions.enableWasmJitEntry) {
+    return true;
+  }
+#endif
+
   // The import may already have become optimized.
   for (auto t : code().tiers()) {
     void* jitExitCode = codeBase(t) + fi.jitExitCodeOffset();

js/src/wasm/WasmJS.cpp

@@ -1490,10 +1490,16 @@ static bool EnsureLazyEntryStub(const Instance& instance,
       return false;
     }
 
+    bool disableJitEntry = funcType.temporarilyUnsupportedAnyRef()
+#ifdef WASM_CODEGEN_DEBUG
+      || !JitOptions.enableWasmJitEntry;
+#endif
+    ;
+
     // Functions with anyref don't have jit entries yet, so they should
     // mostly behave like asm.js functions. Pretend it's the case, until
     // jit entries are implemented.
-    JSFunction::Flags flags = funcType.temporarilyUnsupportedAnyRef()
+    JSFunction::Flags flags = disableJitEntry
                                   ? JSFunction::ASMJS_NATIVE
                                   : JSFunction::WASM_FUN;
 
@@ -1504,7 +1510,7 @@ static bool EnsureLazyEntryStub(const Instance& instance,
       return false;
     }
 
-    if (funcType.temporarilyUnsupportedAnyRef()) {
+    if (disableJitEntry) {
       fun->setAsmJSIndex(funcIndex);
     } else {
       fun->setWasmJitEntry(instance.code().getAddressOfJitEntry(funcIndex));