[wasm] Initialize the root register for WASM tests.

The root register is needed (at least on x64) to access
ExternalReferences.

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/1641153003

Cr-Commit-Position: refs/heads/master@{#33631}

src/compiler/c-linkage.cc

@@ -133,7 +133,7 @@ LinkageLocation regloc(Register reg) {
 
 // General code uses the above configuration data.
 CallDescriptor* Linkage::GetSimplifiedCDescriptor(
-    Zone* zone, const MachineSignature* msig) {
+    Zone* zone, const MachineSignature* msig, bool set_initialize_root_flag) {
   LocationSignature::Builder locations(zone, msig->return_count(),
                                        msig->parameter_count());
 #if 0  // TODO(titzer): instruction selector tests break here.
@@ -220,7 +220,9 @@ CallDescriptor* Linkage::GetSimplifiedCDescriptor(
       Operator::kNoProperties,       // properties
       kCalleeSaveRegisters,          // callee-saved registers
       kCalleeSaveFPRegisters,        // callee-saved fp regs
-      CallDescriptor::kNoFlags,      // flags
+      set_initialize_root_flag ?     // flags
+          CallDescriptor::kInitializeRootRegister
+                               : CallDescriptor::kNoFlags,
       "c-call");
 }
 

src/compiler/code-generator.cc

@@ -78,10 +78,12 @@ Handle<Code> CodeGenerator::GenerateCode() {
   if (linkage()->GetIncomingDescriptor()->IsJSFunctionCall()) {
     ProfileEntryHookStub::MaybeCallEntryHook(masm());
   }
-
   // Architecture-specific, linkage-specific prologue.
   info->set_prologue_offset(masm()->pc_offset());
   AssemblePrologue();
+  if (linkage()->GetIncomingDescriptor()->InitializeRootRegister()) {
+    masm()->InitializeRootRegister();
+  }
 
   // Define deoptimization literals for all inlined functions.
   DCHECK_EQ(0u, deoptimization_literals_.size());

src/compiler/linkage.h

@@ -157,6 +157,8 @@ class CallDescriptor final : public ZoneObject {
     kUseNativeStack = 1u << 7,
     // (arm64 only) call instruction has to restore JSSP.
     kRestoreJSSP = 1u << 8,
+    // Causes the code generator to initialize the root register.
+    kInitializeRootRegister = 1u << 9,
     kPatchableCallSiteWithNop = kPatchableCallSite | kNeedsNopAfterCall
   };
   typedef base::Flags<Flag> Flags;
@@ -223,6 +225,9 @@ class CallDescriptor final : public ZoneObject {
   bool NeedsFrameState() const { return flags() & kNeedsFrameState; }
   bool SupportsTailCalls() const { return flags() & kSupportsTailCalls; }
   bool UseNativeStack() const { return flags() & kUseNativeStack; }
+  bool InitializeRootRegister() const {
+    return flags() & kInitializeRootRegister;
+  }
 
   LinkageLocation GetReturnLocation(size_t index) const {
     return location_sig_->GetReturn(index);
@@ -327,8 +332,9 @@ class Linkage : public ZoneObject {
   // for the host platform. This simplified calling convention only supports
   // integers and pointers of one word size each, i.e. no floating point,
   // structs, pointers to members, etc.
-  static CallDescriptor* GetSimplifiedCDescriptor(Zone* zone,
-                                                  const MachineSignature* sig);
+  static CallDescriptor* GetSimplifiedCDescriptor(
+      Zone* zone, const MachineSignature* sig,
+      bool set_initialize_root_flag = false);
 
   // Creates a call descriptor for interpreter handler code stubs. These are not
   // intended to be called directly but are instead dispatched to by the

src/ia32/macro-assembler-ia32.h

@@ -271,6 +271,9 @@ class MacroAssembler: public Assembler {
   void StoreToSafepointRegisterSlot(Register dst, Immediate src);
   void LoadFromSafepointRegisterSlot(Register dst, Register src);
 
+  // Nop, because ia32 does not have a root register.
+  void InitializeRootRegister() {}
+
   void LoadHeapObject(Register result, Handle<HeapObject> object);
   void CmpHeapObject(Register reg, Handle<HeapObject> object);
   void PushHeapObject(Handle<HeapObject> object);

src/x87/macro-assembler-x87.h

@@ -271,6 +271,9 @@ class MacroAssembler: public Assembler {
   void StoreToSafepointRegisterSlot(Register dst, Immediate src);
   void LoadFromSafepointRegisterSlot(Register dst, Register src);
 
+  // Nop, because x87 does not have a root register.
+  void InitializeRootRegister() {}
+
   void LoadHeapObject(Register result, Handle<HeapObject> object);
   void CmpHeapObject(Register reg, Handle<HeapObject> object);
   void PushHeapObject(Handle<HeapObject> object);

test/cctest/compiler/codegen-tester.h

@@ -35,7 +35,8 @@ class RawMachineAssemblerTester : public HandleAndZoneScope,
             Linkage::GetSimplifiedCDescriptor(
                 main_zone(),
                 CSignature::New(main_zone(), MachineTypeForC<ReturnType>(), p0,
-                                p1, p2, p3, p4)),
+                                p1, p2, p3, p4),
+                true),
             MachineType::PointerRepresentation(),
             InstructionSelector::SupportedMachineOperatorFlags()) {}