Bug 1331414: Adding javascript.options.jit.full_debug_checks in about:config for people that want to use debug builds for surfing with less slowdown, r=jandem

js/src/jit/CodeGenerator.cpp

@@ -5316,8 +5316,10 @@ CodeGenerator::generateBody()
                 extendTrackedOptimizationsEntry(iter->mirRaw()->trackedOptimizations());
 
 #ifdef DEBUG
-            if (!counts)
-                emitDebugResultChecks(*iter);
+            if (!counts) {
+                if (JitOptions.fullDebugChecks)
+                    emitDebugResultChecks(*iter);
+            }
 #endif
         }
         if (masm.oom())

js/src/jit/Ion.cpp

@@ -1906,6 +1906,7 @@ OptimizeMIR(MIRGenerator* mir)
         if (mir->shouldCancel("Make loops contiguous"))
             return false;
     }
+    AssertExtendedGraphCoherency(graph, /* underValueNumberer = */ false, /* force = */ true);
 
     // Passes after this point must not move instructions; these analyses
     // depend on knowing the final order in which instructions will execute.
@@ -1949,6 +1950,8 @@ OptimizeMIR(MIRGenerator* mir)
         AssertGraphCoherency(graph);
     }
 
+    AssertGraphCoherency(graph, /* force = */ true);
+
     DumpMIRExpressions(graph);
 
     return true;
@@ -1992,8 +1995,10 @@ GenerateLIR(MIRGenerator* mir)
           case RegisterAllocator_Backtracking:
           case RegisterAllocator_Testbed: {
 #ifdef DEBUG
-            if (!integrity.record())
-                return nullptr;
+            if (JitOptions.fullDebugChecks) {
+                if (!integrity.record())
+                    return nullptr;
+            }
 #endif
 
             BacktrackingAllocator regalloc(mir, &lirgen, *lir,
@@ -2002,8 +2007,10 @@ GenerateLIR(MIRGenerator* mir)
                 return nullptr;
 
 #ifdef DEBUG
-            if (!integrity.check(false))
-                return nullptr;
+            if (JitOptions.fullDebugChecks) {
+                if (!integrity.check(false))
+                    return nullptr;
+            }
 #endif
 
             gs.spewPass("Allocate Registers [Backtracking]");

js/src/jit/IonAnalysis.cpp

@@ -2701,9 +2701,12 @@ AssertOperandsBeforeSafeInsertTop(MResumePoint* resume)
 #endif // DEBUG
 
 void
-jit::AssertBasicGraphCoherency(MIRGraph& graph)
+jit::AssertBasicGraphCoherency(MIRGraph& graph, bool force)
 {
 #ifdef DEBUG
+    if (!JitOptions.fullDebugChecks && !force)
+        return;
+
     MOZ_ASSERT(graph.entryBlock()->numPredecessors() == 0);
     MOZ_ASSERT(graph.entryBlock()->phisEmpty());
     MOZ_ASSERT(!graph.entryBlock()->unreachable());
@@ -2886,12 +2889,14 @@ AssertDominatorTree(MIRGraph& graph)
 #endif
 
 void
-jit::AssertGraphCoherency(MIRGraph& graph)
+jit::AssertGraphCoherency(MIRGraph& graph, bool force)
 {
 #ifdef DEBUG
     if (!JitOptions.checkGraphConsistency)
         return;
-    AssertBasicGraphCoherency(graph);
+    if (!JitOptions.fullDebugChecks && !force)
+        return;
+    AssertBasicGraphCoherency(graph, force);
     AssertReversePostorder(graph);
 #endif
 }
@@ -2975,7 +2980,7 @@ AssertResumePointDominatedByOperands(MResumePoint* resume)
 #endif // DEBUG
 
 void
-jit::AssertExtendedGraphCoherency(MIRGraph& graph, bool underValueNumberer)
+jit::AssertExtendedGraphCoherency(MIRGraph& graph, bool underValueNumberer, bool force)
 {
     // Checks the basic GraphCoherency but also other conditions that
     // do not hold immediately (such as the fact that critical edges
@@ -2984,8 +2989,10 @@ jit::AssertExtendedGraphCoherency(MIRGraph& graph, bool underValueNumberer)
 #ifdef DEBUG
     if (!JitOptions.checkGraphConsistency)
         return;
+    if (!JitOptions.fullDebugChecks && !force)
+        return;
 
-    AssertGraphCoherency(graph);
+    AssertGraphCoherency(graph, force);
 
     AssertDominatorTree(graph);
 

js/src/jit/IonAnalysis.h

@@ -85,13 +85,13 @@ MOZ_MUST_USE bool
 BuildPhiReverseMapping(MIRGraph& graph);
 
 void
-AssertBasicGraphCoherency(MIRGraph& graph);
+AssertBasicGraphCoherency(MIRGraph& graph, bool force = false);
 
 void
-AssertGraphCoherency(MIRGraph& graph);
+AssertGraphCoherency(MIRGraph& graph, bool force = false);
 
 void
-AssertExtendedGraphCoherency(MIRGraph& graph, bool underValueNumberer = false);
+AssertExtendedGraphCoherency(MIRGraph& graph, bool underValueNumberer = false, bool force = false);
 
 MOZ_MUST_USE bool
 EliminateRedundantChecks(MIRGraph& graph);

js/src/jit/JitOptions.cpp

@@ -164,6 +164,10 @@ DefaultJitOptions::DefaultJitOptions()
     // JSScript::hadFrequentBailouts and invalidate.
     SET_DEFAULT(frequentBailoutThreshold, 10);
 
+    // Whether to run all debug checks in debug builds.
+    // Disabling might make it more enjoyable to run JS in debug builds.
+    SET_DEFAULT(fullDebugChecks, true);
+
     // How many actual arguments are accepted on the C stack.
     SET_DEFAULT(maxStackArgs, 4096);
 

js/src/jit/JitOptions.h

@@ -68,6 +68,7 @@ struct DefaultJitOptions
     bool disableSink;
     bool eagerCompilation;
     bool forceInlineCaches;
+    bool fullDebugChecks;
     bool limitScriptSize;
     bool osr;
     bool asmJSAtomicsEnable;

js/src/jit/MIR.h

@@ -359,7 +359,7 @@ class MNode : public TempObject
 
   protected:
     // Need visibility on getUseFor to avoid O(n^2) complexity.
-    friend void AssertBasicGraphCoherency(MIRGraph& graph);
+    friend void AssertBasicGraphCoherency(MIRGraph& graph, bool force);
 
     // Gets the MUse corresponding to given operand.
     virtual MUse* getUseFor(size_t index) = 0;
@@ -12923,7 +12923,7 @@ class MResumePoint final :
 
   private:
     friend class MBasicBlock;
-    friend void AssertBasicGraphCoherency(MIRGraph& graph);
+    friend void AssertBasicGraphCoherency(MIRGraph& graph, bool force);
 
     // List of stack slots needed to reconstruct the frame corresponding to the
     // function which is compiled by IonBuilder.

js/src/jsapi.cpp

@@ -6423,6 +6423,11 @@ JS_SetGlobalJitCompilerOption(JSContext* cx, JSJitCompilerOption opt, uint32_t v
       case JSJITCOMPILER_ION_INTERRUPT_WITHOUT_SIGNAL:
         jit::JitOptions.ionInterruptWithoutSignals = !!value;
         break;
+#ifdef DEBUG
+      case JSJITCOMPILER_FULL_DEBUG_CHECKS:
+        jit::JitOptions.fullDebugChecks = !!value;
+        break;
+#endif
       default:
         break;
     }
@@ -6470,6 +6475,11 @@ JS_GetGlobalJitCompilerOption(JSContext* cx, JSJitCompilerOption opt, uint32_t*
       case JSJITCOMPILER_ION_INTERRUPT_WITHOUT_SIGNAL:
         *valueOut = jit::JitOptions.ionInterruptWithoutSignals ? 1 : 0;
         break;
+#ifdef DEBUG
+      case JSJITCOMPILER_FULL_DEBUG_CHECKS:
+        *valueOut = jit::JitOptions.fullDebugChecks ? 1 : 0;
+        break;
+#endif
       default:
         return false;
     }

js/src/jsapi.h

@@ -5847,6 +5847,7 @@ JS_SetOffthreadIonCompilationEnabled(JSContext* cx, bool enabled);
     Register(ION_CHECK_RANGE_ANALYSIS, "ion.check-range-analysis")         \
     Register(BASELINE_ENABLE, "baseline.enable")                           \
     Register(OFFTHREAD_COMPILATION_ENABLE, "offthread-compilation.enable") \
+    Register(FULL_DEBUG_CHECKS, "jit.full-debug-checks")                   \
     Register(JUMP_THRESHOLD, "jump-threshold")                             \
     Register(ASMJS_ATOMICS_ENABLE, "asmjs.atomics.enable")                 \
     Register(WASM_TEST_MODE, "wasm.test-mode")                             \

js/xpconnect/src/XPCJSContext.cpp

@@ -1449,6 +1449,7 @@ ReloadPrefsCallback(const char* pref, void* data)
     bool useBaselineEager = Preferences::GetBool(JS_OPTIONS_DOT_STR
                                                  "baselinejit.unsafe_eager_compilation");
     bool useIonEager = Preferences::GetBool(JS_OPTIONS_DOT_STR "ion.unsafe_eager_compilation");
+    bool fullJitDebugChecks = Preferences::GetBool(JS_OPTIONS_DOT_STR "jit.full_debug_checks");
 
     int32_t baselineThreshold = Preferences::GetInt(JS_OPTIONS_DOT_STR "baselinejit.threshold", -1);
     int32_t ionThreshold = Preferences::GetInt(JS_OPTIONS_DOT_STR "ion.threshold", -1);
@@ -1509,6 +1510,9 @@ ReloadPrefsCallback(const char* pref, void* data)
                                   useBaselineEager ? 0 : baselineThreshold);
     JS_SetGlobalJitCompilerOption(cx, JSJITCOMPILER_ION_WARMUP_TRIGGER,
                                   useIonEager ? 0 : ionThreshold);
+#ifdef DEBUG
+    JS_SetGlobalJitCompilerOption(cx, JSJITCOMPILER_FULL_DEBUG_CHECKS, fullJitDebugChecks);
+#endif
 }
 
 XPCJSContext::~XPCJSContext()

modules/libpref/init/all.js

@@ -1259,6 +1259,9 @@ pref("javascript.options.asyncstack",       false);
 #endif
 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);
+#endif
 // This preference instructs the JS engine to discard the
 // source of any privileged JS after compilation. This saves
 // memory, but makes things like Function.prototype.toSource()