Bug 1736405: Remove MLoadElementHole::needsHoleCheck. r=jandem

`MLoadElementHole::needsHoleCheck` is never set to `false`.

Drive-by change:
- Remove two method declarations without definitions.

Differential Revision: https://phabricator.services.mozilla.com/D128762

js/src/jit/CodeGenerator.cpp

@@ -13081,19 +13081,22 @@ void CodeGenerator::visitLoadElementHole(LLoadElementHole* lir) {
 
   masm.loadValue(BaseObjectElementIndex(elements, index), out);
 
-  // If a hole check is needed, and the value wasn't a hole, we're done.
-  // Otherwise, we'll load undefined.
-  if (lir->mir()->needsHoleCheck()) {
-    masm.branchTestMagic(Assembler::NotEqual, out, &done);
-    masm.moveValue(UndefinedValue(), out);
-  }
-  masm.jump(&done);
+  // If the value wasn't a hole, we're done. Otherwise, we'll load undefined.
+  masm.branchTestMagic(Assembler::NotEqual, out, &done);
 
-  masm.bind(&outOfBounds);
   if (mir->needsNegativeIntCheck()) {
+    Label loadUndefined;
+    masm.jump(&loadUndefined);
+
+    masm.bind(&outOfBounds);
+
     Label negative;
     masm.branch32(Assembler::LessThan, index, Imm32(0), &negative);
     bailoutFrom(&negative, lir->snapshot());
+
+    masm.bind(&loadUndefined);
+  } else {
+    masm.bind(&outOfBounds);
   }
   masm.moveValue(UndefinedValue(), out);
 

js/src/jit/CodeGenerator.h

@@ -234,15 +234,9 @@ class CodeGenerator final : public CodeGeneratorSpecific {
                            const ConstantOrRegister& id,
                            const ConstantOrRegister& value, bool strict);
 
-  [[nodiscard]] bool generateBranchV(const ValueOperand& value, Label* ifTrue,
-                                     Label* ifFalse, FloatRegister fr);
-
   void emitLambdaInit(Register resultReg, Register envChainReg,
                       const LambdaFunctionInfo& info);
 
-  void emitFilterArgumentsOrEval(LInstruction* lir, Register string,
-                                 Register temp1, Register temp2);
-
   template <class IteratorObject, class OrderedHashTable>
   void emitGetNextEntryForIterator(LGetNextEntryForIterator* lir);
 

js/src/jit/MIR.h

@@ -6540,14 +6540,11 @@ class MLoadElementAndUnbox : public MBinaryInstruction,
 // Load a value from the elements vector of a native object. If the index is
 // out-of-bounds, or the indexed slot has a hole, undefined is returned instead.
 class MLoadElementHole : public MTernaryInstruction, public NoTypePolicy::Data {
-  bool needsNegativeIntCheck_;
-  bool needsHoleCheck_;
+  bool needsNegativeIntCheck_ = true;
 
   MLoadElementHole(MDefinition* elements, MDefinition* index,
-                   MDefinition* initLength, bool needsHoleCheck)
-      : MTernaryInstruction(classOpcode, elements, index, initLength),
-        needsNegativeIntCheck_(true),
-        needsHoleCheck_(needsHoleCheck) {
+                   MDefinition* initLength)
+      : MTernaryInstruction(classOpcode, elements, index, initLength) {
     setResultType(MIRType::Value);
     setMovable();
 
@@ -6567,15 +6564,11 @@ class MLoadElementHole : public MTernaryInstruction, public NoTypePolicy::Data {
   NAMED_OPERANDS((0, elements), (1, index), (2, initLength))
 
   bool needsNegativeIntCheck() const { return needsNegativeIntCheck_; }
-  bool needsHoleCheck() const { return needsHoleCheck_; }
   bool congruentTo(const MDefinition* ins) const override {
     if (!ins->isLoadElementHole()) {
       return false;
     }
     const MLoadElementHole* other = ins->toLoadElementHole();
-    if (needsHoleCheck() != other->needsHoleCheck()) {
-      return false;
-    }
     if (needsNegativeIntCheck() != other->needsNegativeIntCheck()) {
       return false;
     }

js/src/jit/WarpCacheIRTranspiler.cpp

@@ -1741,9 +1741,7 @@ bool WarpCacheIRTranspiler::emitLoadDenseElementHoleResult(
   auto* length = MInitializedLength::New(alloc(), elements);
   add(length);
 
-  bool needsHoleCheck = true;
-  auto* load =
-      MLoadElementHole::New(alloc(), elements, index, length, needsHoleCheck);
+  auto* load = MLoadElementHole::New(alloc(), elements, index, length);
   add(load);
 
   pushResult(load);

js/src/jit/shared/LIR-shared.h

@@ -1868,10 +1868,6 @@ class LLoadElementHole : public LInstructionHelper<BOX_PIECES, 3, 0> {
     setOperand(2, initLength);
   }
 
-  const char* extraName() const {
-    return mir()->needsHoleCheck() ? "HoleCheck" : nullptr;
-  }
-
   const MLoadElementHole* mir() const { return mir_->toLoadElementHole(); }
   const LAllocation* elements() { return getOperand(0); }
   const LAllocation* index() { return getOperand(1); }