wasm: remove -wasm-abi= flag

This flag controls whether to convert external i64 parameters for use in
a browser-like environment.

This flag was needed in the past because back then we only supported
wasm on browsers but no WASI. Now, I can't think of a reason why anybody
would want to change the default. For `-target=wasm` (used for
browser-like environments), the wasm_exec.js file expects this
i64-via-stack ABI. For WASI, there is no limitation on i64 values and
`-wasm-abi=generic` is the default.

compileopts/config.go

@@ -511,12 +511,8 @@ 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
+// WasmAbi returns the WASM ABI which is specified in the target JSON file.
 func (c *Config) WasmAbi() string {
-	if c.Options.WasmAbi != "" {
-		return c.Options.WasmAbi
-	}
 	return c.Target.WasmAbi
 }
 

compileopts/options.go

@@ -42,7 +42,6 @@ type Options struct {
 	PrintAllocs     *regexp.Regexp // regexp string
 	PrintStacks     bool
 	Tags            []string
-	WasmAbi         string
 	GlobalValues    map[string]map[string]string // map[pkgpath]map[varname]value
 	TestConfig      TestConfig
 	Programmer      string