Remove CodeAssembler::LookupExternalReference

Indirections for external references are now handled completely in
macro assemblers, which can produce more efficient code.

Bug: v8:6666
Change-Id: I158f2e2517e2d97a1006cec6e3b4ac3a7ef3fab6
Reviewed-on: https://chromium-review.googlesource.com/1095307
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53666}

src/arm/macro-assembler-arm.cc

@@ -381,9 +381,7 @@ void TurboAssembler::Move(Register dst, Handle<HeapObject> value) {
 
 void TurboAssembler::Move(Register dst, ExternalReference reference) {
 #ifdef V8_EMBEDDED_BUILTINS
-  if (root_array_available_ && isolate()->ShouldLoadConstantsFromRootList() &&
-      reference.address() !=
-          ExternalReference::roots_array_start(isolate()).address()) {
+  if (root_array_available_ && isolate()->ShouldLoadConstantsFromRootList()) {
     IndirectLoadExternalReference(dst, reference);
     return;
   }

src/compiler/arm/code-generator-arm.cc

@@ -3092,6 +3092,8 @@ void CodeGenerator::AssembleMove(InstructionOperand* source,
       } else {
         __ Move(dst, src_object);
       }
+    } else if (src.type() == Constant::kExternalReference) {
+      __ Move(dst, src.ToExternalReference());
     } else {
       __ mov(dst, g.ToImmediate(source));
     }

src/compiler/arm64/code-generator-arm64.cc

@@ -2592,6 +2592,8 @@ void CodeGenerator::AssembleMove(InstructionOperand* source,
       } else {
         __ Move(dst, src_object);
       }
+    } else if (src.type() == Constant::kExternalReference) {
+      __ Mov(dst, src.ToExternalReference());
     } else {
       __ Mov(dst, g.ToImmediate(source));
     }

src/compiler/code-assembler.cc

@@ -6,7 +6,6 @@
 
 #include <ostream>
 
-#include "src/builtins/constants-table-builder.h"
 #include "src/code-factory.h"
 #include "src/compiler/graph.h"
 #include "src/compiler/instruction-selector.h"
@@ -22,7 +21,6 @@
 #include "src/machine-type.h"
 #include "src/macro-assembler.h"
 #include "src/objects-inl.h"
-#include "src/snapshot/serializer-common.h"
 #include "src/utils.h"
 #include "src/zone/zone.h"
 
@@ -259,34 +257,6 @@ void CodeAssembler::GenerateCheckMaybeObjectIsObject(Node* node,
 }
 #endif
 
-#ifdef V8_EMBEDDED_BUILTINS
-// External references are stored in the external reference table.
-TNode<ExternalReference> CodeAssembler::LookupExternalReference(
-    ExternalReference reference) {
-  DCHECK(isolate()->ShouldLoadConstantsFromRootList());
-
-  // Encode as an index into the external reference table stored on the isolate.
-
-  ExternalReferenceEncoder encoder(isolate());
-  ExternalReferenceEncoder::Value v = encoder.Encode(reference.address());
-  CHECK(!v.is_from_api());
-  uint32_t index = v.index();
-
-  // Generate code to load from the external reference table.
-
-  const intptr_t roots_to_external_reference_offset =
-      Heap::roots_to_external_reference_table_offset()
-#ifdef V8_TARGET_ARCH_X64
-      - kRootRegisterBias
-#endif
-      + ExternalReferenceTable::OffsetOfEntry(index);
-
-  return UncheckedCast<ExternalReference>(
-      Load(MachineType::Pointer(), LoadRootsPointer(),
-           IntPtrConstant(roots_to_external_reference_offset)));
-}
-#endif  // V8_EMBEDDED_BUILTINS
-
 TNode<Int32T> CodeAssembler::Int32Constant(int32_t value) {
   return UncheckedCast<Int32T>(raw_assembler()->Int32Constant(value));
 }
@@ -339,11 +309,6 @@ TNode<Oddball> CodeAssembler::BooleanConstant(bool value) {
 
 TNode<ExternalReference> CodeAssembler::ExternalConstant(
     ExternalReference address) {
-#ifdef V8_EMBEDDED_BUILTINS
-  if (isolate()->ShouldLoadConstantsFromRootList()) {
-    return LookupExternalReference(address);
-  }
-#endif  // V8_EMBEDDED_BUILTINS
   return UncheckedCast<ExternalReference>(
       raw_assembler()->ExternalConstant(address));
 }
@@ -504,6 +469,7 @@ Node* CodeAssembler::LoadParentFramePointer() {
   return raw_assembler()->LoadParentFramePointer();
 }
 
+// TODO(jgruber): This can be removed.
 TNode<IntPtrT> CodeAssembler::LoadRootsPointer() {
   return UncheckedCast<IntPtrT>(raw_assembler()->LoadRootsPointer());
 }
@@ -981,6 +947,9 @@ TNode<Object> CodeAssembler::LoadRoot(Heap::RootListIndex root_index) {
     }
   }
 
+  // TODO(jgruber): In theory we could generate better code for this by
+  // letting the macro assembler decide how to load from the roots list. In most
+  // cases, it would boil down to loading from a fixed kRootRegister offset.
   Node* roots_array_start =
       ExternalConstant(ExternalReference::roots_array_start(isolate()));
   return UncheckedCast<Object>(Load(MachineType::AnyTagged(), roots_array_start,

src/compiler/code-assembler.h

@@ -694,10 +694,6 @@ class V8_EXPORT_PRIVATE CodeAssembler {
   void GenerateCheckMaybeObjectIsObject(Node* node, const char* location);
 #endif
 
-#ifdef V8_EMBEDDED_BUILTINS
-  TNode<ExternalReference> LookupExternalReference(ExternalReference reference);
-#endif
-
   // Constants.
   TNode<Int32T> Int32Constant(int32_t value);
   TNode<Int64T> Int64Constant(int64_t value);

src/compiler/mips/code-generator-mips.cc

@@ -3359,7 +3359,7 @@ void CodeGenerator::AssembleMove(InstructionOperand* source,
           __ li(dst, Operand::EmbeddedNumber(src.ToFloat64().value()));
           break;
         case Constant::kExternalReference:
-          __ li(dst, Operand(src.ToExternalReference()));
+          __ li(dst, src.ToExternalReference());
           break;
         case Constant::kHeapObject: {
           Handle<HeapObject> src_object = src.ToHeapObject();

src/compiler/mips64/code-generator-mips64.cc

@@ -3612,7 +3612,7 @@ void CodeGenerator::AssembleMove(InstructionOperand* source,
           __ li(dst, Operand::EmbeddedNumber(src.ToFloat64().value()));
           break;
         case Constant::kExternalReference:
-          __ li(dst, Operand(src.ToExternalReference()));
+          __ li(dst, src.ToExternalReference());
           break;
         case Constant::kHeapObject: {
           Handle<HeapObject> src_object = src.ToHeapObject();

src/ppc/macro-assembler-ppc.cc

@@ -353,9 +353,7 @@ void TurboAssembler::Move(Register dst, Handle<HeapObject> value) {
 
 void TurboAssembler::Move(Register dst, ExternalReference reference) {
 #ifdef V8_EMBEDDED_BUILTINS
-  if (root_array_available_ && isolate()->ShouldLoadConstantsFromRootList() &&
-      reference.address() !=
-          ExternalReference::roots_array_start(isolate()).address()) {
+  if (root_array_available_ && isolate()->ShouldLoadConstantsFromRootList()) {
     IndirectLoadExternalReference(dst, reference);
     return;
   }

src/s390/macro-assembler-s390.cc

@@ -346,9 +346,7 @@ void TurboAssembler::Move(Register dst, Handle<HeapObject> value) {
 
 void TurboAssembler::Move(Register dst, ExternalReference reference) {
 #ifdef V8_EMBEDDED_BUILTINS
-  if (root_array_available_ && isolate()->ShouldLoadConstantsFromRootList() &&
-      reference.address() !=
-          ExternalReference::roots_array_start(isolate()).address()) {
+  if (root_array_available_ && isolate()->ShouldLoadConstantsFromRootList()) {
     IndirectLoadExternalReference(dst, reference);
     return;
   }

src/turbo-assembler.cc

@@ -62,8 +62,6 @@ void TurboAssemblerBase::IndirectLoadConstant(Register destination,
 
 void TurboAssemblerBase::IndirectLoadExternalReference(
     Register destination, ExternalReference reference) {
-  CHECK(reference.address() !=
-        ExternalReference::roots_array_start(isolate()).address());
   CHECK(isolate()->ShouldLoadConstantsFromRootList());
   CHECK(root_array_available_);
 

src/x64/macro-assembler-x64.cc

@@ -1069,9 +1069,7 @@ void TurboAssembler::Move(Register dst, Smi* source) {
 
 void TurboAssembler::Move(Register dst, ExternalReference ext) {
 #ifdef V8_EMBEDDED_BUILTINS
-  if (root_array_available_ && isolate()->ShouldLoadConstantsFromRootList() &&
-      ext.address() !=
-          ExternalReference::roots_array_start(isolate()).address()) {
+  if (root_array_available_ && isolate()->ShouldLoadConstantsFromRootList()) {
     IndirectLoadExternalReference(dst, ext);
     return;
   }