interpreter: fixes V128FloatPromote to use lower 64-bits. (#709)

Signed-off-by: Takeshi Yoneda <takeshi@tetrate.io>

internal/engine/interpreter/interpreter.go

@@ -3826,9 +3826,9 @@ func (ce *callEngine) callNativeFunc(ctx context.Context, callCtx *wasm.CallCont
 			ce.pushValue(retHi)
 			frame.pc++
 		case wazeroir.OperationKindV128FloatPromote:
-			hi, lo := ce.popValue(), ce.popValue()
-			ce.pushValue(math.Float64bits(float64(math.Float32frombits(uint32(lo)))))
-			ce.pushValue(math.Float64bits(float64(math.Float32frombits(uint32(hi)))))
+			_, toPromote := ce.popValue(), ce.popValue()
+			ce.pushValue(math.Float64bits(float64(math.Float32frombits(uint32(toPromote)))))
+			ce.pushValue(math.Float64bits(float64(math.Float32frombits(uint32(toPromote >> 32)))))
 			frame.pc++
 		case wazeroir.OperationKindV128FloatDemote:
 			hi, lo := ce.popValue(), ce.popValue()

internal/integration_test/fuzzcases/fuzzcases_test.go

@@ -25,6 +25,8 @@ var (
 	case704 []byte
 	//go:embed testdata/708.wasm
 	case708 []byte
+	//go:embed testdata/709.wasm
+	case709 []byte
 )
 
 func newRuntimeCompiler() wazero.Runtime {
@@ -193,3 +195,32 @@ func Test708(t *testing.T) {
 		})
 	}
 }
+
+func Test709(t *testing.T) {
+	if !platform.CompilerSupported() {
+		return
+	}
+
+	for _, tc := range []struct {
+		name string
+		r    wazero.Runtime
+	}{
+		{name: "compiler", r: newRuntimeCompiler()},
+		{name: "interpreter", r: newRuntimeInterpreter()},
+	} {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			defer tc.r.Close(ctx)
+			mod, err := tc.r.InstantiateModuleFromBinary(ctx, case709)
+			require.NoError(t, err)
+
+			f := mod.ExportedFunction("f64x2.promote_low_f32x4")
+			require.NotNil(t, f)
+			res, err := f.Call(ctx)
+			require.NoError(t, err)
+
+			require.NotEqual(t, uint64(0), res[0])
+			require.NotEqual(t, uint64(0), res[1])
+		})
+	}
+}

internal/integration_test/fuzzcases/testdata/709.wat

@@ -0,0 +1,9 @@
+(module
+  (func (result v128)
+    v128.const i32x4 0xffffffff 0xffffffff 0 0
+    ;; This should promote two 32-bit floats on the lower 64-bits (0xffffffff x2)
+    ;; Therefore, the returned vector must have non zero lower and higher 64-bits.
+    f64x2.promote_low_f32x4
+  )
+  (export "f64x2.promote_low_f32x4" (func 0))
+)

internal/wazeroir/operations.go

@@ -2722,6 +2722,8 @@ func (OperationV128ExtAddPairwise) Kind() OperationKind {
 // OperationV128FloatPromote implements Operation.
 //
 // This corresponds to wasm.OpcodeVecF64x2PromoteLowF32x4ZeroName
+// This discards the higher 64-bit of a vector, and promotes two
+// 32-bit floats in the lower 64-bit as two 64-bit floats.
 type OperationV128FloatPromote struct{}
 
 // Kind implements Operation.Kind.