[wasm] Remove obsolete i-cache flushes.

Now that we no longer use code specialization to patch WasmCode after it
was generated, we no longer need to flush the instruction cache after
instance building finishes.

R=clemensh@chromium.org

Change-Id: I4ce31876dde9c6dcc4ad945e024641b72330fe4f
Reviewed-on: https://chromium-review.googlesource.com/1128975Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54333}

src/wasm/module-compiler.cc

@@ -6,7 +6,6 @@
 
 #include "src/api.h"
 #include "src/asmjs/asm-js.h"
-#include "src/assembler-inl.h"
 #include "src/base/optional.h"
 #include "src/base/template-utils.h"
 #include "src/base/utils/random-number-generator.h"
@@ -389,8 +388,6 @@ wasm::WasmCode* LazyCompileFunction(Isolate* isolate,
   auto counters = isolate->counters();
   counters->wasm_lazily_compiled_functions()->Increment();
 
-  Assembler::FlushICache(wasm_code->instructions().start(),
-                         wasm_code->instructions().size());
   counters->wasm_generated_code_size()->Increment(
       static_cast<int>(wasm_code->instructions().size()));
   counters->wasm_reloc_size()->Increment(
@@ -426,17 +423,6 @@ bool compile_lazy(const WasmModule* module) {
          (FLAG_asm_wasm_lazy_compilation && module->origin == kAsmJsOrigin);
 }
 
-void FlushICache(const wasm::NativeModule* native_module) {
-  for (uint32_t i = native_module->num_imported_functions(),
-                e = native_module->num_functions();
-       i < e; ++i) {
-    const wasm::WasmCode* code = native_module->code(i);
-    if (code == nullptr) continue;
-    Assembler::FlushICache(code->instructions().start(),
-                           code->instructions().size());
-  }
-}
-
 byte* raw_buffer_ptr(MaybeHandle<JSArrayBuffer> buffer, int offset) {
   return static_cast<byte*>(buffer.ToHandleChecked()->backing_store()) + offset;
 }
@@ -1211,11 +1197,6 @@ MaybeHandle<WasmInstanceObject> InstanceBuilder::Build() {
     LoadDataSegments(instance);
   }
 
-  //--------------------------------------------------------------------------
-  // Flush the processors instruction cache.
-  //--------------------------------------------------------------------------
-  FlushICache(native_module);
-
   //--------------------------------------------------------------------------
   // Install a finalizer on the new instance object.
   //--------------------------------------------------------------------------