add wasm-abi field in TargetSpec && set generic for WASI by default (#1421)

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

compileopts/config.go

@@ -329,6 +329,15 @@ func (c *Config) RelocationModel() string {
 	return "static"
 }
 
+// WasmAbi returns the WASM ABI which is specified in the target JSON file, and
+// the value is overridden by `-wasm-abi` flag if it is provided
+func (c *Config) WasmAbi() string {
+	if c.Options.WasmAbi != "" {
+		return c.Options.WasmAbi
+	}
+	return c.Target.WasmAbi
+}
+
 type TestConfig struct {
 	CompileTestBinary bool
 	// TODO: Filter the test functions to run, include verbose flag, etc

compileopts/target.go

@@ -55,6 +55,7 @@ type TargetSpec struct {
 	JLinkDevice      string   `json:"jlink-device"`
 	CodeModel        string   `json:"code-model"`
 	RelocationModel  string   `json:"relocation-model"`
+	WasmAbi          string   `json:"wasm-abi"`
 }
 
 // overrideProperties overrides all properties that are set in child into itself using reflection.