[wasm] Load jump table start from the instance

This makes js-to-wasm wrappers module-independent, so that we can
eventually share them isolate-wide.

R=mstarzinger@chromium.org

Bug: chromium:862123
Change-Id: I3d9571cf247b95330ffb17f41901278a5dfacca0
Reviewed-on: https://chromium-review.googlesource.com/1131187
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54363}

src/compiler/wasm-compiler.cc

@@ -4404,8 +4404,7 @@ class WasmWrapperGraphBuilder : public WasmGraphBuilder {
     return function_index;
   }
 
-  void BuildJSToWasmWrapper(Address jump_table_start, bool is_import,
-                            uint32_t num_imported_functions) {
+  void BuildJSToWasmWrapper(bool is_import) {
     const int wasm_count = static_cast<int>(sig_->parameter_count());
 
     // Build the start and the JS parameter nodes.
@@ -4466,13 +4465,10 @@ class WasmWrapperGraphBuilder : public WasmGraphBuilder {
     } else {
       // Call to a wasm function defined in this module.
       // The call target is the jump table slot for that function. This is
-      // {jump_table + (func_index - num_imports) * kJumpTableSlotSize}.
-      // Compute as
-      //   jump_table_adjusted (static) := jump_table - num_imports * kJTSS.
-      //   call_target := jump_table_adjusted + func_index * kJTSS.
-      Node* jump_table_adjusted = mcgraph()->IntPtrConstant(
-          jump_table_start - num_imported_functions *
-                                 wasm::JumpTableAssembler::kJumpTableSlotSize);
+      // {jump_table + (func_index - num_imports) * kJumpTableSlotSize}
+      // == {jump_table_adjusted + func_index * kJumpTableSlotSize}.
+      Node* jump_table_adjusted =
+          LOAD_INSTANCE_FIELD(JumpTableAdjustedStart, MachineType::Pointer());
       Node* jump_table_offset = graph()->NewNode(
           mcgraph()->machine()->IntMul(), Uint32ToUintptr(function_index),
           mcgraph()->IntPtrConstant(
@@ -4828,8 +4824,7 @@ MaybeHandle<Code> CompileJSToWasmWrapper(
                                   StubCallMode::kCallOnHeapBuiltin);
   builder.set_control_ptr(&control);
   builder.set_effect_ptr(&effect);
-  builder.BuildJSToWasmWrapper(native_module->jump_table_start(), is_import,
-                               module->num_imported_functions);
+  builder.BuildJSToWasmWrapper(is_import);
 
   //----------------------------------------------------------------------------
   // Run the compilation pipeline.

src/compiler/wasm-compiler.h

@@ -116,9 +116,11 @@ MaybeHandle<Code> CompileWasmToJSWrapper(Isolate*, Handle<JSReceiver> target,
 
 // Creates a code object calling a wasm function with the given signature,
 // callable from JS.
+// TODO(clemensh): Remove the {UseTrapHandler} parameter to make js-to-wasm
+// wrappers sharable across instances.
 V8_EXPORT_PRIVATE MaybeHandle<Code> CompileJSToWasmWrapper(
     Isolate*, const wasm::NativeModule*, wasm::FunctionSig*, bool is_import,
-    wasm::UseTrapHandler use_trap_handler);
+    wasm::UseTrapHandler);
 
 // Compiles a stub that redirects a call to a wasm function to the wasm
 // interpreter. It's ABI compatible with the compiled wasm function.

src/wasm/wasm-objects-inl.h

@@ -156,6 +156,8 @@ PRIMITIVE_ACCESSORS(WasmInstanceObject, indirect_function_table_sig_ids,
                     uint32_t*, kIndirectFunctionTableSigIdsOffset)
 PRIMITIVE_ACCESSORS(WasmInstanceObject, indirect_function_table_targets,
                     Address*, kIndirectFunctionTableTargetsOffset)
+PRIMITIVE_ACCESSORS(WasmInstanceObject, jump_table_adjusted_start, Address,
+                    kJumpTableAdjustedStartOffset)
 
 ACCESSORS(WasmInstanceObject, module_object, WasmModuleObject,
           kModuleObjectOffset)

src/wasm/wasm-objects.cc

@@ -13,6 +13,7 @@
 #include "src/objects-inl.h"
 #include "src/objects/debug-objects-inl.h"
 #include "src/trap-handler/trap-handler.h"
+#include "src/wasm/jump-table-assembler.h"
 #include "src/wasm/module-compiler.h"
 #include "src/wasm/module-decoder.h"
 #include "src/wasm/wasm-code-manager.h"
@@ -1263,6 +1264,10 @@ Handle<WasmInstanceObject> WasmInstanceObject::New(
   instance->set_module_object(*module_object);
   instance->set_undefined_value(ReadOnlyRoots(isolate).undefined_value());
   instance->set_null_value(ReadOnlyRoots(isolate).null_value());
+  instance->set_jump_table_adjusted_start(
+      module_object->native_module()->jump_table_start() -
+      wasm::JumpTableAssembler::kJumpTableSlotSize *
+          module->num_imported_functions);
 
   // Insert the new instance into the modules weak list of instances.
   // TODO(mstarzinger): Allow to reuse holes in the {WeakArrayList} below.

src/wasm/wasm-objects.h

@@ -401,6 +401,7 @@ class WasmInstanceObject : public JSObject {
   DECL_PRIMITIVE_ACCESSORS(indirect_function_table_size, uint32_t)
   DECL_PRIMITIVE_ACCESSORS(indirect_function_table_sig_ids, uint32_t*)
   DECL_PRIMITIVE_ACCESSORS(indirect_function_table_targets, Address*)
+  DECL_PRIMITIVE_ACCESSORS(jump_table_adjusted_start, Address)
 
   // Dispatched behavior.
   DECL_PRINTER(WasmInstanceObject)
@@ -435,6 +436,7 @@ class WasmInstanceObject : public JSObject {
   V(kImportedMutableGlobalsOffset, kPointerSize)         /* untagged */ \
   V(kIndirectFunctionTableSigIdsOffset, kPointerSize)    /* untagged */ \
   V(kIndirectFunctionTableTargetsOffset, kPointerSize)   /* untagged */ \
+  V(kJumpTableAdjustedStartOffset, kPointerSize)         /* untagged */ \
   V(kIndirectFunctionTableSizeOffset, kUInt32Size)       /* untagged */ \
   V(k64BitArchPaddingOffset, kPointerSize - kUInt32Size) /* padding */  \
   V(kSize, 0)