Implement f{32,64}.copysign instructions

wasmx · Aug 11, 2020 · 219777c · 219777c
1 parent c0d88e1
commit 219777c
Show file tree

Hide file tree

Showing 2 changed files with 43 additions and 2 deletions.
diff --git a/lib/fizzy/execute.cpp b/lib/fizzy/execute.cpp
@@ -1470,6 +1470,16 @@ ExecutionResult execute(Instance& instance, FuncIdx func_idx, span<const Value>
             binary_op(stack, std::divides<float>{});
             break;
         }
+        case Instr::f32_copysign:
+        {
+            // TODO: This is not optimal implementation. The std::copysign() is inlined, but
+            //       it afects the compiler to still use SSE vectors (probably due to C++ABI)
+            //       while this can be implemented with just generic registers and integer
+            //       instructions: (a & ABS_MASK) | (b & SIGN_MASK).
+            //       https://godbolt.org/z/aPqvfo
+            binary_op(stack, std::copysign<float, float>);
+            break;
+        }
 
         case Instr::f64_add:
         {
@@ -1481,6 +1491,11 @@ ExecutionResult execute(Instance& instance, FuncIdx func_idx, span<const Value>
             binary_op(stack, std::divides<double>{});
             break;
         }
+        case Instr::f64_copysign:
+        {
+            binary_op(stack, std::copysign<double, double>);
+            break;
+        }
 
         case Instr::i32_wrap_i64:
         {
@@ -1586,7 +1601,6 @@ ExecutionResult execute(Instance& instance, FuncIdx func_idx, span<const Value>
         case Instr::f32_mul:
         case Instr::f32_min:
         case Instr::f32_max:
-        case Instr::f32_copysign:
         case Instr::f64_abs:
         case Instr::f64_neg:
         case Instr::f64_ceil:
@@ -1598,7 +1612,6 @@ ExecutionResult execute(Instance& instance, FuncIdx func_idx, span<const Value>
         case Instr::f64_mul:
         case Instr::f64_min:
         case Instr::f64_max:
-        case Instr::f64_copysign:
         case Instr::f32_convert_i32_s:
         case Instr::f32_convert_i32_u:
         case Instr::f32_convert_i64_s:

diff --git a/test/unittests/execute_floating_point_test.cpp b/test/unittests/execute_floating_point_test.cpp
@@ -382,6 +382,34 @@ TYPED_TEST(execute_floating_point_types, div)
     EXPECT_THAT(exec(TypeParam{0xABCD.01p7}, TypeParam{4}), Result(TypeParam{0x1.579A02p20}));
 }
 
+TYPED_TEST(execute_floating_point_types, copysign)
+{
+    using FP = FP<TypeParam>;
+    using Limits = typename FP::Limits;
+
+    auto instance = instantiate(parse(this->get_binop_code(Instr::f32_copysign)));
+    const auto exec = [&](auto arg1, auto arg2) { return execute(*instance, 0, {arg1, arg2}); };
+
+    std::vector p_values(std::begin(this->q_values), std::end(this->q_values));
+    for (const auto x :
+        {TypeParam{0}, Limits::infinity(), FP::nan(FP::canon), FP::nan(FP::canon + 1), FP::nan(1)})
+        p_values.push_back(x);
+
+    for (const auto p1 : p_values)
+    {
+        for (const auto p2 : p_values)
+        {
+            // fcopysign(+-p1, +-p2) = +-p1
+            EXPECT_THAT(exec(p1, p2), Result(p1));
+            EXPECT_THAT(exec(-p1, -p2), Result(-p1));
+
+            // fcopysign(+-p1, -+p2) = -+p1
+            EXPECT_THAT(exec(p1, -p2), Result(-p1));
+            EXPECT_THAT(exec(-p1, p2), Result(p1));
+        }
+    }
+}
+
 
 template <typename SrcT, typename DstT>
 struct ConversionPairWasmTraits;