// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: BSD-3-Clause

#include "textflag.h"

// ABI0 JIT trampoline for RISC-V 64.
//
// enterJIT saves Go SP and RA, switches to the prepared stack, and jumps
// to the JIT function.  When the function RETs (JALR zero, ra, 0), control
// lands in leaveJIT.

// func enterJIT(fn uintptr, stack uintptr)
TEXT ·enterJIT(SB), NOSPLIT, $0-16
	MOV  fn+0(FP), X5 // target function address (T0)
	MOV  X1, savedRA(SB) // save return address
	MOV  X2, savedSP(SB) // save Go stack pointer
	MOV  stack+8(FP), X6 // load prepared stack pointer (T1)
	LD   0(X6), X1 // load leaveJIT address into RA
	MOV  X6, X2 // switch to the prepared stack: SP stays on
	// the leave slot, so the kernel reads its
	// first argument at SP+8
	JALR X0, 0(X5) // jump to JIT function

	// func leaveJIT()
TEXT ·leaveJIT(SB), NOSPLIT, $0-0
	MOV  savedSP(SB), X6 // restore Go stack pointer
	MOV  X6, X2 // restore SP
	MOV  savedRA(SB), X1 // restore return address
	JALR X0, 0(X1) // return to Go caller

GLOBL savedRA(SB), NOPTR, $8

GLOBL savedSP(SB), NOPTR, $8