feat(asm): the operand forms and defines GOROOT writes

Assisted-by: GLM 5.3 Flash

testdata/verify/forms_amd64.s

@@ -0,0 +1,36 @@
+// Kernel: the operand forms the GOROOT campaign surfaced — numeric
+// PC-relative jumps, symbol-immediate materialisation (the toolchain rewrites
+// MOVQ $sym(SB) into a RIP-relative LEA) and the negated constant-expression
+// ADJSP the cgo ABI macros write.  Bytes are pinned against go tool asm by
+// TestDifferentialKernels.
+#include "textflag.h"
+
+DATA sd<>(SB)/4, $7
+GLOBL sd<>(SB), RODATA, $4
+
+// func Jumps(flag int64) int64
+TEXT ·Jumps(SB), NOSPLIT, $0-16
+	MOVQ	flag+0(FP), AX
+	TESTQ	AX, AX
+	JEQ	2(PC)
+	MOVQ	$1, AX
+	JMP	3(PC)
+	MOVQ	$2, AX
+	MOVQ	AX, ret+0(FP)
+	RET
+
+// func SymImm() int64
+TEXT ·SymImm(SB), NOSPLIT, $0-16
+	MOVQ	$sd<>(SB), AX
+	MOVQ	$·SymImm(SB), CX
+	MOVQ	AX, ret+0(FP)
+	RET
+
+// func Frame()
+TEXT ·Frame(SB), NOSPLIT, $0
+	PUSHFQ
+	CLD
+	ADJSP	$(64 - 8)
+	ADJSP	$-(64 - 8)
+	POPFQ
+	RET