feat(riscv64,loong64): operand tail, float DATA and honest port classification

Assisted-by: GLM 5.3 Flash

testdata/verify/bookkeep_riscv64.s

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+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Differential kernel for the riscv64 bookkeeping statements and the
+// slot-relative branches: FUNCDATA and PCDATA (the expanded forms of the
+// funcdata.h macros, contributing no bytes), UNDEF (the toolchain's ebreak),
+// and the JMP N(PC) slot jumps including the self-loop and the backward form.
+
+#include "textflag.h"
+
+TEXT ·bookkeep(SB), NOSPLIT, $8-8
+	FUNCDATA $1, marks<>(SB)
+	PCDATA   $1, $-1
+	MOV      ZERO, ret+0(FP)
+	PCDATA   $1, $1
+	UNDEF
+	MOV      $1, X10
+	RET
+
+TEXT ·slots(SB), NOSPLIT, $0-0
+	MOV $1, X10
+	JMP 2(PC)
+	MOV $64, X11
+	MOV $128, X12
+	MOV $2, X11
+	MOV $3, X12
+	BEQ X10, X11, skip
+	JMP -2(PC)
+
+skip:
+	JMP 0(PC)
+
+TEXT ·marksreader(SB), NOSPLIT, $0-8
+	MOV $marks<>(SB), X10
+	MOV (X10), X11
+	MOV X11, ret+0(FP)
+	RET
+
+GLOBL marks<>(SB), RODATA, $8
+DATA marks<>+0(SB)/8, $1234605616436508552