Convert float64 to float32 when coerced with a heapf32 assignment.

src/wasm/asm-wasm-builder.cc

 // Copyright 2015 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 "src/v8.h"
 
 // Required to get M_E etc. in MSVC.
 #if defined(_WIN32)
 #define _USE_MATH_DEFINES
 #endif
@@ skipping 676 matching lines @@
       VariableProxy* effective_value_var = GetLeft(value_op)->AsVariableProxy();
       if (target_var != nullptr && effective_value_var != nullptr &&
           target_var->var() == effective_value_var->var()) {
         block_size_--;
         return;
       }
     }
     is_set_op_ = true;
     RECURSE(Visit(expr->target()));
     DCHECK(!is_set_op_);
+    // Assignment to heapf32 from float64 converts.
+    if (TypeOf(expr->value()) == kAstF64 && expr->target()->IsProperty() &&
+        expr->target()->AsProperty()->obj()->bounds().lower->Is(
+            cache_.kFloat32Array)) {
+      current_function_builder_->Emit(kExprF32ConvertF64);
+    }
     RECURSE(Visit(expr->value()));
     if (in_init) {
       UnLoadInitFunction();
     }
   }
 
   void VisitYield(Yield* expr) { UNREACHABLE(); }
 
   void VisitThrow(Throw* expr) { UNREACHABLE(); }
 
@@ skipping 798 matching lines @@
 // that zone in constructor may be thrown away once wasm module is written.
 WasmModuleIndex* AsmWasmBuilder::Run() {
   AsmWasmBuilderImpl impl(isolate_, zone_, literal_, foreign_, typer_);
   impl.Compile();
   WasmModuleWriter* writer = impl.builder_->Build(zone_);
   return writer->WriteTo(zone_);
 }
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8