[wasm] Remove dead handling of RUNTIME_ENTRY relocations.

The RelocInfo::RUNTIME_ENTRY relocation mode is only used for deopt
points in JavaScript code and should never appear in WebAssembly code.

R=titzer@chromium.org

Change-Id: Ied1d61e2b1eb886565d13448442dd6a6ed35d3f0
Reviewed-on: https://chromium-review.googlesource.com/1070197Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53340}

src/wasm/wasm-code-manager.cc

@@ -255,6 +255,39 @@ void WasmCode::LogCode(Isolate* isolate) const {
   }
 }
 
+void WasmCode::Validate() const {
+#ifdef DEBUG
+  // We expect certain relocation info modes to never appear in {WasmCode}
+  // objects or to be restricted to a small set of valid values. Hence the
+  // iteration below does not use a mask, but visits all relocation data.
+  for (RelocIterator it(instructions(), reloc_info(), constant_pool());
+       !it.done(); it.next()) {
+    RelocInfo::Mode mode = it.rinfo()->rmode();
+    switch (mode) {
+      case RelocInfo::CODE_TARGET:
+      // TODO(mstarzinger): Validate that we go through a trampoline.
+      case RelocInfo::WASM_CODE_TABLE_ENTRY:
+      case RelocInfo::WASM_GLOBAL_HANDLE:
+      case RelocInfo::WASM_CALL:
+      case RelocInfo::JS_TO_WASM_CALL:
+      case RelocInfo::EXTERNAL_REFERENCE:
+      case RelocInfo::COMMENT:
+      case RelocInfo::CONST_POOL:
+      case RelocInfo::VENEER_POOL:
+        // These are OK to appear.
+        break;
+      case RelocInfo::EMBEDDED_OBJECT: {
+        HeapObject* o = it.rinfo()->target_object();
+        DCHECK(o->IsUndefined(o->GetIsolate()) || o->IsNull(o->GetIsolate()));
+        break;
+      }
+      default:
+        FATAL("Unexpected mode: %d", mode);
+    }
+  }
+#endif
+}
+
 void WasmCode::Print(Isolate* isolate) const {
   OFStream os(stdout);
   Disassemble(nullptr, isolate, os);
@@ -550,7 +583,6 @@ WasmCode* NativeModule::AddCode(
   // TODO(mtrofin): this is a copy and paste from Code::CopyFrom.
   int mode_mask = RelocInfo::kCodeTargetMask |
                   RelocInfo::ModeMask(RelocInfo::EMBEDDED_OBJECT) |
-                  RelocInfo::ModeMask(RelocInfo::RUNTIME_ENTRY) |
                   RelocInfo::kApplyMask;
   // Needed to find target_object and runtime_entry on X64
 
@@ -570,10 +602,6 @@ WasmCode* NativeModule::AddCode(
       Code* code = Code::cast(*p);
       it.rinfo()->set_target_address(GetLocalAddressFor(handle(code)),
                                      SKIP_WRITE_BARRIER, SKIP_ICACHE_FLUSH);
-    } else if (RelocInfo::IsRuntimeEntry(mode)) {
-      Address p = it.rinfo()->target_runtime_entry(origin);
-      it.rinfo()->set_target_runtime_entry(p, SKIP_WRITE_BARRIER,
-                                           SKIP_ICACHE_FLUSH);
     } else {
       intptr_t delta = ret->instructions().start() - desc.buffer;
       it.rinfo()->apply(delta);
@@ -583,6 +611,7 @@ WasmCode* NativeModule::AddCode(
   // made while iterating over the RelocInfo above.
   Assembler::FlushICache(ret->instructions().start(),
                          ret->instructions().size());
+  ret->Validate();
   return ret;
 }
 

src/wasm/wasm-code-manager.h

@@ -135,6 +135,7 @@ class V8_EXPORT_PRIVATE WasmCode final {
   // trap_handler_index.
   void RegisterTrapHandlerData();
 
+  void Validate() const;
   void Print(Isolate* isolate) const;
   void Disassemble(const char* name, Isolate* isolate, std::ostream& os,
                    Address current_pc = kNullAddress) const;

src/wasm/wasm-serialization.cc

@@ -316,7 +316,6 @@ void NativeModuleSerializer::WriteCode(const WasmCode* code, Writer* writer) {
   // Relocate the code.
   int mask = RelocInfo::ModeMask(RelocInfo::CODE_TARGET) |
              RelocInfo::ModeMask(RelocInfo::WASM_CALL) |
-             RelocInfo::ModeMask(RelocInfo::RUNTIME_ENTRY) |
              RelocInfo::ModeMask(RelocInfo::EXTERNAL_REFERENCE);
   RelocIterator orig_iter(code->instructions(), code->reloc_info(),
                           code->constant_pool(), mask);
@@ -337,13 +336,6 @@ void NativeModuleSerializer::WriteCode(const WasmCode* code, Writer* writer) {
         uint32_t tag = wasm_targets_lookup_[orig_target];
         SetWasmCalleeTag(iter.rinfo(), tag);
       } break;
-      case RelocInfo::RUNTIME_ENTRY: {
-        Address orig_target = orig_iter.rinfo()->target_address();
-        auto ref_iter = reference_table_lookup_.find(orig_target);
-        DCHECK(ref_iter != reference_table_lookup_.end());
-        uint32_t tag = ref_iter->second;
-        SetWasmCalleeTag(iter.rinfo(), tag);
-      } break;
       case RelocInfo::EXTERNAL_REFERENCE: {
         Address orig_target = orig_iter.rinfo()->target_external_reference();
         auto ref_iter = reference_table_lookup_.find(orig_target);
@@ -491,7 +483,6 @@ bool NativeModuleDeserializer::ReadCode(uint32_t fn_index, Reader* reader) {
   // now relocate the code
   int mask = RelocInfo::ModeMask(RelocInfo::EMBEDDED_OBJECT) |
              RelocInfo::ModeMask(RelocInfo::CODE_TARGET) |
-             RelocInfo::ModeMask(RelocInfo::RUNTIME_ENTRY) |
              RelocInfo::ModeMask(RelocInfo::EXTERNAL_REFERENCE) |
              RelocInfo::ModeMask(RelocInfo::WASM_CODE_TABLE_ENTRY);
   for (RelocIterator iter(ret->instructions(), ret->reloc_info(),
@@ -512,14 +503,6 @@ bool NativeModuleDeserializer::ReadCode(uint32_t fn_index, Reader* reader) {
                                          SKIP_ICACHE_FLUSH);
         break;
       }
-      case RelocInfo::RUNTIME_ENTRY: {
-        uint32_t tag = GetWasmCalleeTag(iter.rinfo());
-        Address address =
-            isolate_->heap()->external_reference_table()->address(tag);
-        iter.rinfo()->set_target_runtime_entry(address, SKIP_WRITE_BARRIER,
-                                               SKIP_ICACHE_FLUSH);
-        break;
-      }
       case RelocInfo::EXTERNAL_REFERENCE: {
         uint32_t tag = GetWasmCalleeTag(iter.rinfo());
         Address address =