[assembler] Simplify {PatchingAssembler} cache flushing.

R=clemensh@chromium.org

Change-Id: Icfe73151ddc0d6a8afaed89004614e1a7c4e9416
Reviewed-on: https://chromium-review.googlesource.com/909531
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51221}

src/arm/assembler-arm.cc

@@ -5479,10 +5479,6 @@ void PatchingAssembler::Emit(Address addr) {
   emit(reinterpret_cast<Instr>(addr));
 }
 
-void PatchingAssembler::FlushICache(Isolate* isolate) {
-  Assembler::FlushICache(buffer_, buffer_size_ - kGap);
-}
-
 UseScratchRegisterScope::UseScratchRegisterScope(Assembler* assembler)
     : assembler_(assembler),
       old_available_(*assembler->GetScratchRegisterList()),

src/arm/assembler-arm.h

@@ -1787,7 +1787,6 @@ class PatchingAssembler : public Assembler {
   ~PatchingAssembler();
 
   void Emit(Address addr);
-  void FlushICache(Isolate* isolate);
 };
 
 // This scope utility allows scratch registers to be managed safely. The

src/arm64/assembler-arm64.h

@@ -3677,18 +3677,9 @@ class PatchingAssembler : public Assembler {
   // 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.
-
-  // This version will flush at destruction.
-  PatchingAssembler(Isolate* isolate, byte* start, unsigned count)
-      : PatchingAssembler(IsolateData(isolate), start, count) {
-    CHECK_NOT_NULL(isolate);
-    isolate_ = isolate;
-  }
-
-  // This version will not flush.
+  // Note that the instruction cache will not be flushed.
   PatchingAssembler(IsolateData isolate_data, byte* start, unsigned count)
-      : Assembler(isolate_data, start, count * kInstructionSize + kGap),
-        isolate_(nullptr) {
+      : Assembler(isolate_data, start, count * kInstructionSize + kGap) {
     // Block constant pool emission.
     StartBlockPools();
   }
@@ -3701,18 +3692,12 @@ class PatchingAssembler : public Assembler {
     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;
-    if (isolate_ != nullptr) Assembler::FlushICache(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_;
 };
 
 

src/ppc/assembler-ppc.cc

@@ -2150,10 +2150,6 @@ PatchingAssembler::~PatchingAssembler() {
   DCHECK_EQ(reloc_info_writer.pos(), buffer_ + buffer_size_);
 }
 
-void PatchingAssembler::FlushICache(Isolate* isolate) {
-  Assembler::FlushICache(buffer_, buffer_size_ - kGap);
-}
-
 }  // namespace internal
 }  // namespace v8
 

src/ppc/assembler-ppc.h

@@ -1658,8 +1658,6 @@ class PatchingAssembler : public Assembler {
  public:
   PatchingAssembler(IsolateData isolate_data, byte* address, int instructions);
   ~PatchingAssembler();
-
-  void FlushICache(Isolate* isolate);
 };
 
 }  // namespace internal