Disentangle assembler from isolate.

src/arm64/assembler-arm64.h

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_ARM64_ASSEMBLER_ARM64_H_
 #define V8_ARM64_ASSEMBLER_ARM64_H_
 
 #include <deque>
 #include <list>
 #include <map>
@@ skipping 699 matching lines @@
   // for a detailed comment on the layout (globals.h).
   //
   // If the provided buffer is NULL, the assembler allocates and grows its own
   // buffer, and buffer_size determines the initial buffer size. The buffer is
   // owned by the assembler and deallocated upon destruction of the assembler.
   //
   // If the provided buffer is not NULL, the assembler uses the provided buffer
   // for code generation and assumes its size to be buffer_size. If the buffer
   // is too small, a fatal error occurs. No deallocation of the buffer is done
   // upon destruction of the assembler.
-  Assembler(Isolate* arg_isolate, void* buffer, int buffer_size);
+  Assembler(Isolate* isolate, void* buffer, int buffer_size)
+      : Assembler(IsolateData(isolate), buffer, buffer_size) {}
+  Assembler(IsolateData isolate_data, void* buffer, int buffer_size);
 
   virtual ~Assembler();
 
   virtual void AbortedCodeGeneration() {
     constpool_.Clear();
   }
 
   // System functions ---------------------------------------------------------
   // Start generating code from the beginning of the buffer, discarding any code
   // and data that has already been emitted into the buffer.
@@ skipping 30 matching lines @@
   // RelocInfo and pools ------------------------------------------------------
 
   // Record relocation information for current pc_.
   void RecordRelocInfo(RelocInfo::Mode rmode, intptr_t data = 0);
 
   // Return the address in the constant pool of the code target address used by
   // the branch/call instruction at pc.
   inline static Address target_pointer_address_at(Address pc);
 
   // Read/Modify the code target address in the branch/call instruction at pc.
+  // The isolate argument is unused (and may be nullptr) when skipping flushing.
   inline static Address target_address_at(Address pc, Address constant_pool);
   inline static void set_target_address_at(
       Isolate* isolate, Address pc, Address constant_pool, Address target,
       ICacheFlushMode icache_flush_mode = FLUSH_ICACHE_IF_NEEDED);
   static inline Address target_address_at(Address pc, Code* code);
   static inline void set_target_address_at(
       Isolate* isolate, Address pc, Code* code, Address target,
       ICacheFlushMode icache_flush_mode = FLUSH_ICACHE_IF_NEEDED);
 
   // Return the code target address at a call site from the return address of
@@ skipping 1257 matching lines @@
   int const_pool_blocked_nesting_;  // Block emission if this is not zero.
   int no_const_pool_before_;  // Block emission before this pc offset.
 
   // Emission of the veneer pools may be blocked in some code sequences.
   int veneer_pool_blocked_nesting_;  // Block emission if this is not zero.
 
   // Relocation info generation
   // Each relocation is encoded as a variable size value
   static constexpr int kMaxRelocSize = RelocInfoWriter::kMaxSize;
   RelocInfoWriter reloc_info_writer;
+
   // Internal reference positions, required for (potential) patching in
   // GrowBuffer(); contains only those internal references whose labels
   // are already bound.
   std::deque<int> internal_reference_positions_;
 
   // Relocation info records are also used during code generation as temporary
   // containers for constants and code target addresses until they are emitted
   // to the constant pool. These pending relocation info records are temporarily
   // stored in a separate buffer until a constant pool is emitted.
   // If every instruction in a long sequence is accessing the pool, we need one
@@ skipping 91 matching lines @@
 class PatchingAssembler : public Assembler {
  public:
   // Create an Assembler with a buffer starting at 'start'.
   // The buffer size is
   //   size of instructions to patch + kGap
   // Where kGap is the distance from which the Assembler tries to grow the
   // buffer.
   // If more or fewer instructions than expected are generated or if some
   // relocation information takes space in the buffer, the PatchingAssembler
   // will crash trying to grow the buffer.
-  PatchingAssembler(Isolate* isolate, Instruction* start, unsigned count)
-      : Assembler(isolate, reinterpret_cast<byte*>(start),
-                  count * kInstructionSize + kGap) {
-    StartBlockPools();
+
+  // This version will flush at destruction.
+  PatchingAssembler(Isolate* isolate, byte* start, unsigned count)
+      : PatchingAssembler(IsolateData(isolate), start, count) {
+    CHECK_NOT_NULL(isolate);
+    isolate_ = isolate;
   }
 
-  PatchingAssembler(Isolate* isolate, byte* start, unsigned count)
-      : Assembler(isolate, start, count * kInstructionSize + kGap) {
+  // This version will not flush.
+  PatchingAssembler(IsolateData isolate_data, byte* start, unsigned count)
+      : Assembler(isolate_data, start, count * kInstructionSize + kGap),
+        isolate_(nullptr) {
     // Block constant pool emission.
     StartBlockPools();
   }
 
   ~PatchingAssembler() {
     // Const pool should still be blocked.
     DCHECK(is_const_pool_blocked());
     EndBlockPools();
     // Verify we have generated the number of instruction we expected.
     DCHECK((pc_offset() + kGap) == buffer_size_);
     // Verify no relocation information has been emitted.
     DCHECK(IsConstPoolEmpty());
     // Flush the Instruction cache.
     size_t length = buffer_size_ - kGap;
-    Assembler::FlushICache(isolate(), buffer_, length);
+    if (isolate_ != nullptr) Assembler::FlushICache(isolate_, buffer_, length);
   }
 
   // See definition of PatchAdrFar() for details.
   static constexpr int kAdrFarPatchableNNops = 2;
   static constexpr int kAdrFarPatchableNInstrs = kAdrFarPatchableNNops + 2;
   void PatchAdrFar(int64_t target_offset);
+
+ private:
+  Isolate* isolate_;
 };
 
 
 class EnsureSpace BASE_EMBEDDED {
  public:
   explicit EnsureSpace(Assembler* assembler) {
     assembler->CheckBufferSpace();
   }
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_ARM64_ASSEMBLER_ARM64_H_