[js] Remove pointless MakeMRegExpHoistable optimization.

It's a lot of code with no measurable effect.

6 files changed, 4 insertions, 302 deletions

diff --git a/js/src/jit/Ion.cpp b/js/src/jit/Ion.cpp
index 9337f6150..aa0ba8e3d 100644
--- a/js/src/jit/Ion.cpp
+++ b/js/src/jit/Ion.cpp
@@ -1497,14 +1497,6 @@ OptimizeMIR(MIRGenerator* mir)
     if (mir->shouldCancel("Start"))
         return false;
 
-    if (!mir->compilingWasm()) {
-        if (!MakeMRegExpHoistable(mir, graph))
-            return false;
-
-        if (mir->shouldCancel("Make MRegExp Hoistable"))
-            return false;
-    }
-
     gs.spewPass("BuildSSA");
     AssertBasicGraphCoherency(graph);
 
diff --git a/js/src/jit/IonAnalysis.cpp b/js/src/jit/IonAnalysis.cpp
index 8bad8ba9c..a78ef232c 100644
--- a/js/src/jit/IonAnalysis.cpp
+++ b/js/src/jit/IonAnalysis.cpp
@@ -1975,274 +1975,6 @@ jit::ApplyTypeInformation(MIRGenerator* mir, MIRGraph& graph)
     return true;
 }
 
-// Check if `def` is only the N-th operand of `useDef`.
-static inline size_t
-IsExclusiveNthOperand(MDefinition* useDef, size_t n, MDefinition* def)
-{
-    uint32_t num = useDef->numOperands();
-    if (n >= num || useDef->getOperand(n) != def)
-        return false;
-
-    for (uint32_t i = 0; i < num; i++) {
-        if (i == n)
-            continue;
-        if (useDef->getOperand(i) == def)
-            return false;
-    }
-
-    return true;
-}
-
-static size_t
-IsExclusiveThisArg(MCall* call, MDefinition* def)
-{
-    return IsExclusiveNthOperand(call, MCall::IndexOfThis(), def);
-}
-
-static size_t
-IsExclusiveFirstArg(MCall* call, MDefinition* def)
-{
-    return IsExclusiveNthOperand(call, MCall::IndexOfArgument(0), def);
-}
-
-static bool
-IsRegExpHoistableCall(MCall* call, MDefinition* def)
-{
-    if (call->isConstructing())
-        return false;
-
-    JSAtom* name;
-    if (WrappedFunction* fun = call->getSingleTarget()) {
-        if (!fun->isSelfHostedBuiltin())
-            return false;
-        name = GetSelfHostedFunctionName(fun->rawJSFunction());
-    } else {
-        MDefinition* funDef = call->getFunction();
-        if (funDef->isDebugCheckSelfHosted())
-            funDef = funDef->toDebugCheckSelfHosted()->input();
-        if (funDef->isTypeBarrier())
-            funDef = funDef->toTypeBarrier()->input();
-
-        if (!funDef->isCallGetIntrinsicValue())
-            return false;
-        name = funDef->toCallGetIntrinsicValue()->name();
-    }
-
-    // Hoistable only if the RegExp is the first argument of RegExpBuiltinExec.
-    CompileRuntime* runtime = GetJitContext()->runtime;
-    if (name == runtime->names().RegExpBuiltinExec ||
-        name == runtime->names().UnwrapAndCallRegExpBuiltinExec ||
-        name == runtime->names().RegExpMatcher ||
-        name == runtime->names().RegExpTester ||
-        name == runtime->names().RegExpSearcher)
-    {
-        return IsExclusiveFirstArg(call, def);
-    }
-
-    if (name == runtime->names().RegExp_prototype_Exec)
-        return IsExclusiveThisArg(call, def);
-
-    return false;
-}
-
-static bool
-CanCompareRegExp(MCompare* compare, MDefinition* def)
-{
-    MDefinition* value;
-    if (compare->lhs() == def) {
-        value = compare->rhs();
-    } else {
-        MOZ_ASSERT(compare->rhs() == def);
-        value = compare->lhs();
-    }
-
-    // Comparing two regexp that weren't cloned will give different result
-    // than if they were cloned.
-    if (value->mightBeType(MIRType::Object))
-        return false;
-
-    // Make sure @@toPrimitive is not called which could notice
-    // the difference between a not cloned/cloned regexp.
-
-    JSOp op = compare->jsop();
-    // Strict equality comparison won't invoke @@toPrimitive.
-    if (op == JSOP_STRICTEQ || op == JSOP_STRICTNE)
-        return true;
-
-    if (op != JSOP_EQ && op != JSOP_NE) {
-        // Relational comparison always invoke @@toPrimitive.
-        MOZ_ASSERT(op == JSOP_GT || op == JSOP_GE || op == JSOP_LT || op == JSOP_LE);
-        return false;
-    }
-
-    // Loose equality comparison can invoke @@toPrimitive.
-    if (value->mightBeType(MIRType::Boolean) || value->mightBeType(MIRType::String) ||
-        value->mightBeType(MIRType::Int32) ||
-        value->mightBeType(MIRType::Double) || value->mightBeType(MIRType::Float32) ||
-        value->mightBeType(MIRType::Symbol))
-    {
-        return false;
-    }
-
-    return true;
-}
-
-static inline void
-SetNotInWorklist(MDefinitionVector& worklist)
-{
-    for (size_t i = 0; i < worklist.length(); i++)
-        worklist[i]->setNotInWorklist();
-}
-
-static bool
-IsRegExpHoistable(MIRGenerator* mir, MDefinition* regexp, MDefinitionVector& worklist,
-                  bool* hoistable)
-{
-    MOZ_ASSERT(worklist.length() == 0);
-
-    if (!worklist.append(regexp))
-        return false;
-    regexp->setInWorklist();
-
-    for (size_t i = 0; i < worklist.length(); i++) {
-        MDefinition* def = worklist[i];
-        if (mir->shouldCancel("IsRegExpHoistable outer loop"))
-            return false;
-
-        for (MUseIterator use = def->usesBegin(); use != def->usesEnd(); use++) {
-            if (mir->shouldCancel("IsRegExpHoistable inner loop"))
-                return false;
-
-            // Ignore resume points. At this point all uses are listed.
-            // No DCE or GVN or something has happened.
-            if (use->consumer()->isResumePoint())
-                continue;
-
-            MDefinition* useDef = use->consumer()->toDefinition();
-
-            // Step through a few white-listed ops.
-            if (useDef->isPhi() || useDef->isFilterTypeSet() || useDef->isGuardShape()) {
-                if (useDef->isInWorklist())
-                    continue;
-
-                if (!worklist.append(useDef))
-                    return false;
-                useDef->setInWorklist();
-                continue;
-            }
-
-            // Instructions that doesn't invoke unknown code that may modify
-            // RegExp instance or pass it to elsewhere.
-            if (useDef->isRegExpMatcher() || useDef->isRegExpTester() ||
-                useDef->isRegExpSearcher())
-            {
-                if (IsExclusiveNthOperand(useDef, 0, def))
-                    continue;
-            } else if (useDef->isLoadFixedSlot() || useDef->isTypeOf()) {
-                continue;
-            } else if (useDef->isCompare()) {
-                if (CanCompareRegExp(useDef->toCompare(), def))
-                    continue;
-            }
-            // Instructions that modifies `lastIndex` property.
-            else if (useDef->isStoreFixedSlot()) {
-                if (IsExclusiveNthOperand(useDef, 0, def)) {
-                    MStoreFixedSlot* store = useDef->toStoreFixedSlot();
-                    if (store->slot() == RegExpObject::lastIndexSlot())
-                        continue;
-                }
-            } else if (useDef->isSetPropertyCache()) {
-                if (IsExclusiveNthOperand(useDef, 0, def)) {
-                    MSetPropertyCache* setProp = useDef->toSetPropertyCache();
-                    if (setProp->idval()->isConstant()) {
-                        Value propIdVal = setProp->idval()->toConstant()->toJSValue();
-                        if (propIdVal.isString()) {
-                            CompileRuntime* runtime = GetJitContext()->runtime;
-                            if (propIdVal.toString() == runtime->names().lastIndex)
-                                continue;
-                        }
-                    }
-                }
-            }
-            // MCall is safe only for some known safe functions.
-            else if (useDef->isCall()) {
-                if (IsRegExpHoistableCall(useDef->toCall(), def))
-                    continue;
-            }
-
-            // Everything else is unsafe.
-            SetNotInWorklist(worklist);
-            worklist.clear();
-            *hoistable = false;
-
-            return true;
-        }
-    }
-
-    SetNotInWorklist(worklist);
-    worklist.clear();
-    *hoistable = true;
-    return true;
-}
-
-bool
-jit::MakeMRegExpHoistable(MIRGenerator* mir, MIRGraph& graph)
-{
-    // If we are compiling try blocks, regular expressions may be observable
-    // from catch blocks (which Ion does not compile). For now just disable the
-    // pass in this case.
-    if (graph.hasTryBlock())
-        return true;
-
-    MDefinitionVector worklist(graph.alloc());
-
-    for (ReversePostorderIterator block(graph.rpoBegin()); block != graph.rpoEnd(); block++) {
-        if (mir->shouldCancel("MakeMRegExpHoistable outer loop"))
-            return false;
-
-        for (MDefinitionIterator iter(*block); iter; iter++) {
-            if (!*iter)
-                MOZ_CRASH("confirm bug 1263794.");
-
-            if (mir->shouldCancel("MakeMRegExpHoistable inner loop"))
-                return false;
-
-            if (!iter->isRegExp())
-                continue;
-
-            MRegExp* regexp = iter->toRegExp();
-
-            bool hoistable = false;
-            if (!IsRegExpHoistable(mir, regexp, worklist, &hoistable))
-                return false;
-
-            if (!hoistable)
-                continue;
-
-            // Make MRegExp hoistable
-            regexp->setMovable();
-            regexp->setDoNotClone();
-
-            // That would be incorrect for global/sticky, because lastIndex
-            // could be wrong.  Therefore setting the lastIndex to 0. That is
-            // faster than a not movable regexp.
-            RegExpObject* source = regexp->source();
-            if (source->sticky() || source->global()) {
-                if (!graph.alloc().ensureBallast())
-                    return false;
-                MConstant* zero = MConstant::New(graph.alloc(), Int32Value(0));
-                regexp->block()->insertAfter(regexp, zero);
-
-                MStoreFixedSlot* lastIndex =
-                    MStoreFixedSlot::New(graph.alloc(), regexp, RegExpObject::lastIndexSlot(), zero);
-                regexp->block()->insertAfter(zero, lastIndex);
-            }
-        }
-    }
-
-    return true;
-}
-
 void
 jit::RenumberBlocks(MIRGraph& graph)
 {
diff --git a/js/src/jit/IonAnalysis.h b/js/src/jit/IonAnalysis.h
index 49bc0b591..673c797bd 100644
--- a/js/src/jit/IonAnalysis.h
+++ b/js/src/jit/IonAnalysis.h
@@ -56,9 +56,6 @@ EliminateDeadCode(MIRGenerator* mir, MIRGraph& graph);
 MOZ_MUST_USE bool
 ApplyTypeInformation(MIRGenerator* mir, MIRGraph& graph);
 
-MOZ_MUST_USE bool
-MakeMRegExpHoistable(MIRGenerator* mir, MIRGraph& graph);
-
 void
 RenumberBlocks(MIRGraph& graph);
 
diff --git a/js/src/jit/Lowering.cpp b/js/src/jit/Lowering.cpp
index 19266bae8..f9b0b2157 100644
--- a/js/src/jit/Lowering.cpp
+++ b/js/src/jit/Lowering.cpp
@@ -2297,14 +2297,9 @@ LIRGenerator::visitToObjectOrNull(MToObjectOrNull* ins)
 void
 LIRGenerator::visitRegExp(MRegExp* ins)
 {
-    if (ins->mustClone()) {
-        LRegExp* lir = new(alloc()) LRegExp();
-        defineReturn(lir, ins);
-        assignSafepoint(lir, ins);
-    } else {
-        RegExpObject* source = ins->source();
-        define(new(alloc()) LPointer(source), ins);
-    }
+    LRegExp* lir = new(alloc()) LRegExp();
+    defineReturn(lir, ins);
+    assignSafepoint(lir, ins);
 }
 
 void
diff --git a/js/src/jit/MIR.h b/js/src/jit/MIR.h
index af0abc695..81662a9be 100644
--- a/js/src/jit/MIR.h
+++ b/js/src/jit/MIR.h
@@ -8102,11 +8102,9 @@ class MDefFun
 class MRegExp : public MNullaryInstruction
 {
     CompilerGCPointer<RegExpObject*> source_;
-    bool mustClone_;
 
     MRegExp(CompilerConstraintList* constraints, RegExpObject* source)
-      : source_(source),
-        mustClone_(true)
+      : source_(source)
     {
         setResultType(MIRType::Object);
         setResultTypeSet(MakeSingletonTypeSet(constraints, source));
@@ -8116,12 +8114,6 @@ class MRegExp : public MNullaryInstruction
     INSTRUCTION_HEADER(RegExp)
     TRIVIAL_NEW_WRAPPERS
 
-    void setDoNotClone() {
-        mustClone_ = false;
-    }
-    bool mustClone() const {
-        return mustClone_;
-    }
     RegExpObject* source() const {
         return source_;
     }
diff --git a/js/src/vm/CommonPropertyNames.h b/js/src/vm/CommonPropertyNames.h
index 6a8afb56b..420ee7535 100644
--- a/js/src/vm/CommonPropertyNames.h
+++ b/js/src/vm/CommonPropertyNames.h
@@ -281,13 +281,8 @@
     macro(proxy, proxy, "proxy") \
     macro(raw, raw, "raw") \
     macro(reason, reason, "reason") \
-    macro(RegExpBuiltinExec, RegExpBuiltinExec, "RegExpBuiltinExec") \
     macro(RegExpFlagsGetter, RegExpFlagsGetter, "RegExpFlagsGetter") \
-    macro(RegExpMatcher, RegExpMatcher, "RegExpMatcher") \
-    macro(RegExpSearcher, RegExpSearcher, "RegExpSearcher") \
     macro(RegExpStringIterator, RegExpStringIterator, "RegExp String Iterator") \
-    macro(RegExpTester, RegExpTester, "RegExpTester") \
-    macro(RegExp_prototype_Exec, RegExp_prototype_Exec, "RegExp_prototype_Exec") \
     macro(Reify, Reify, "Reify") \
     macro(reject, reject, "reject") \
     macro(rejected, rejected, "rejected") \
@@ -360,7 +355,6 @@
     macro(uninitialized, uninitialized, "uninitialized") \
     macro(unsized, unsized, "unsized") \
     macro(unwatch, unwatch, "unwatch") \
-    macro(UnwrapAndCallRegExpBuiltinExec, UnwrapAndCallRegExpBuiltinExec, "UnwrapAndCallRegExpBuiltinExec") \
     macro(url, url, "url") \
     macro(usage, usage, "usage") \
     macro(useAsm, useAsm, "use asm") \