fix(asm): close the oracle parity gaps in frame addressing and calls

testdata/verify/bigframe_riscv64.s

@@ -0,0 +1,25 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Large frame offsets and tail calls, byte-parity-checked against go tool asm.
+
+#include "textflag.h"
+
+TEXT ·bigframe(SB), $9000-32
+	MOV x+0(FP), X5
+	MOV y+8(FP), X6
+	MOV X5, z+24(FP)
+	MOV $77, X7
+	MOV X7, w+8992(FP)
+	RET
+
+TEXT ·oddsp(SB), $16-8
+	MOV X5, x-9000(SP)
+	MOV X5, ret+0(FP)
+	RET
+
+TEXT ·tail(SB), $0-0
+	JMP ·other(SB)
+
+TEXT ·other(SB), NOSPLIT, $0
+	RET