struct with a field named "type", x._type accesses the field.
C struct fields that cannot be expressed in Go, such as bit fields
or misaligned data, are omitted in the Go struct, replaced by
appropriate padding to reach the next field or the end of the struct.

The standard C numeric types are available under the names
C.char, C.schar (signed char), C.uchar (unsigned char),
C.short, C.ushort (unsigned short), C.int, C.uint (unsigned int),

<p>
"If" statements specify the conditional execution of two branches
according to the value of a boolean expression.  If the expression
evaluates to true, the "if" branch is executed, otherwise, if
present, the "else" branch is executed.
</p>

<pre class="ebnf">
IfStmt = "if" [ SimpleStmt ";" ] Expression Block [ "else" ( IfStmt | Block ) ] .
</pre>

<pre>
if x &gt; max {
	x = max

	for _, patch := range p.toPatch {
		targetProg := p.labels[patch.label]
		if targetProg == nil {
			p.errorf("undefined label %s", patch.label)
			return
		}
		p.branch(patch.addr, targetProg)
	}
	p.toPatch = p.toPatch[:0]
}

func (p *Parser) branch(addr *obj.Addr, target *obj.Prog) {
	*addr = obj.Addr{
		Type:  obj.TYPE_BRANCH,
		Index: 0,
	}
	addr.Val = target
}

<p>
"If" statements specify the conditional execution of two branches
according to the value of a boolean expression.  If the expression
evaluates to true, the "if" branch is executed, otherwise, if
present, the "else" branch is executed.
</p>

<pre class="ebnf">
IfStmt = "if" [ SimpleStmt ";" ] Expression Block [ "else" ( IfStmt | Block ) ] .
</pre>

<pre>
if x &gt; max {
	x = max

	// the real address and updates the immediate, using a trampoline in
	// the case where the address is not directly reachable.
	CALL	asmtest(SB)				// ef000000
	JMP	asmtest(SB)				// 6f000000

	// Branch pseudo-instructions
	BEQZ	X5, 2(PC)				// 63840200
	BGEZ	X5, 2(PC)				// 63d40200
	BGT	X5, X6, 2(PC)				// 63445300
	BGTU	X5, X6, 2(PC)				// 63645300
	BGTZ	X5, 2(PC)				// 63445000
	BLE	X5, X6, 2(PC)				// 63545300