[wasm] Backoff implementation for F64Trunc using std::trunc.

test/cctest/compiler/test-run-machops.cc

 // Copyright 2014 the V8 project authors. All rights reserved. Use of this
 // source code is governed by a BSD-style license that can be found in the
 // LICENSE file.
 
 #include <cmath>
 #include <functional>
 #include <limits>
 
 #include "src/base/bits.h"
 #include "src/base/utils/random-number-generator.h"
@@ skipping 5570 matching lines @@
       MachineType::Int32(), MachineType::Int32(), MachineType::Int32(),
       MachineType::Int32(), MachineType::Int32(), MachineType::Int32(),
       function, param, param, param, param, param, param, param, param));
   FOR_INT32_INPUTS(i) {
     int32_t const x = *i;
     CHECK_EQ(x * 8, m.Call(x));
   }
 }
 #endif  // USE_SIMULATOR
 
+TEST(RunCallExternalReferenceF64Trunc) {
+  BufferedRawMachineAssemblerTester<double> m(MachineType::Float64());
+  Node* stack_slot = m.StackSlot(MachineRepresentation::kFloat64);
+  m.Store(MachineRepresentation::kFloat64, stack_slot, m.Parameter(0),
+          WriteBarrierKind::kNoWriteBarrier);
+  Node* function = m.ExternalConstant(
+      ExternalReference::trunc64_wrapper_function(m.isolate()));
+  m.CallCFunction1(MachineType::Pointer(), MachineType::Pointer(), function,
+                   stack_slot);
+  m.Return(m.Load(MachineType::Float64(), stack_slot));
+  FOR_FLOAT64_INPUTS(i) { CheckDoubleEq(trunc(*i), m.Call(*i)); }
+}
+
 #if V8_TARGET_ARCH_64_BIT
 // TODO(titzer): run int64 tests on all platforms when supported.
 TEST(RunCheckedLoadInt64) {
   int64_t buffer[] = {0x66bbccddeeff0011LL, 0x1122334455667788LL};
   RawMachineAssemblerTester<int64_t> m(MachineType::Int32());
   Node* base = m.PointerConstant(buffer);
   Node* index = m.Parameter(0);
   Node* length = m.Int32Constant(16);
   Node* load = m.AddNode(m.machine()->CheckedLoad(MachineType::Int64()), base,
                          index, length);
@@ skipping 484 matching lines @@
   Node* call = r.AddNode(r.common()->Call(desc), phi);
   r.Return(call);
 
   CHECK_EQ(33, r.Call(1));
   CHECK_EQ(44, r.Call(0));
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8