[Qemu-devel] [RFC v1 19/23] riscv: tcg-target: Add the prologue generation

[Alistair Francis]

Signed-off-by: Alistair Francis <address@hidden>
Signed-off-by: Michael Clark <address@hidden>
---
 tcg/riscv/tcg-target.inc.c | 66 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)

diff --git a/tcg/riscv/tcg-target.inc.c b/tcg/riscv/tcg-target.inc.c
index bf3b04f7dc..4b8f65f367 100644
--- a/tcg/riscv/tcg-target.inc.c
+++ b/tcg/riscv/tcg-target.inc.c
@@ -1575,6 +1575,72 @@ static const TCGTargetOpDef *tcg_target_op_def(TCGOpcode 
op)
     }
 }
 
+static const int tcg_target_callee_save_regs[] = {
+    TCG_REG_S0,       /* used for the global env (TCG_AREG0) */
+    TCG_REG_S1,
+    TCG_REG_S2,
+    TCG_REG_S3,
+    TCG_REG_S4,
+    TCG_REG_S5,
+    TCG_REG_S6,
+    TCG_REG_S7,
+    TCG_REG_S8,
+    TCG_REG_S9,
+    TCG_REG_S10,
+    TCG_REG_S11,
+    TCG_REG_RA,       /* should be last for ABI compliance */
+};
+
+/* Stack frame parameters.  */
+#define REG_SIZE   (TCG_TARGET_REG_BITS / 8)
+#define SAVE_SIZE  ((int)ARRAY_SIZE(tcg_target_callee_save_regs) * REG_SIZE)
+#define TEMP_SIZE  (CPU_TEMP_BUF_NLONGS * (int)sizeof(long))
+#define FRAME_SIZE ((TCG_STATIC_CALL_ARGS_SIZE + TEMP_SIZE + SAVE_SIZE \
+                     + TCG_TARGET_STACK_ALIGN - 1) \
+                    & -TCG_TARGET_STACK_ALIGN)
+#define SAVE_OFS   (TCG_STATIC_CALL_ARGS_SIZE + TEMP_SIZE)
+
+/* We're expecting to be able to use an immediate for frame allocation.  */
+QEMU_BUILD_BUG_ON(FRAME_SIZE > 0x7ff);
+
+/* Generate global QEMU prologue and epilogue code */
+static void tcg_target_qemu_prologue(TCGContext *s)
+{
+    int i;
+
+    tcg_set_frame(s, TCG_REG_SP, TCG_STATIC_CALL_ARGS_SIZE, TEMP_SIZE);
+
+    /* TB prologue */
+    tcg_out_opc_imm(s, OPC_ADDI, TCG_REG_SP, TCG_REG_SP, -FRAME_SIZE);
+    for (i = 0; i < ARRAY_SIZE(tcg_target_callee_save_regs); i++) {
+        tcg_out_st(s, TCG_TYPE_REG, tcg_target_callee_save_regs[i],
+                   TCG_REG_SP, SAVE_OFS + i * REG_SIZE);
+    }
+
+#if !defined(CONFIG_SOFTMMU)
+    tcg_out_movi(s, TCG_TYPE_PTR, TCG_GUEST_BASE_REG, guest_base);
+    tcg_regset_set_reg(s->reserved_regs, TCG_GUEST_BASE_REG);
+#endif
+
+    /* Call generated code */
+    tcg_out_mov(s, TCG_TYPE_PTR, TCG_AREG0, tcg_target_call_iarg_regs[0]);
+    tcg_out_opc_imm(s, OPC_JALR, TCG_REG_ZERO, tcg_target_call_iarg_regs[1], 
0);
+
+    /* Return path for goto_ptr. Set return value to 0 */
+    s->code_gen_epilogue = s->code_ptr;
+    tcg_out_mov(s, TCG_TYPE_REG, TCG_REG_A0, TCG_REG_ZERO);
+
+    /* TB epilogue */
+    tb_ret_addr = s->code_ptr;
+    for (i = 0; i < ARRAY_SIZE(tcg_target_callee_save_regs); i++) {
+        tcg_out_ld(s, TCG_TYPE_REG, tcg_target_callee_save_regs[i],
+                   TCG_REG_SP, SAVE_OFS + i * REG_SIZE);
+    }
+
+    tcg_out_opc_imm(s, OPC_ADDI, TCG_REG_SP, TCG_REG_SP, FRAME_SIZE);
+    tcg_out_opc_imm(s, OPC_JALR, TCG_REG_ZERO, TCG_REG_RA, 0);
+}
+
 void tb_target_set_jmp_target(uintptr_t tc_ptr, uintptr_t jmp_addr,
                               uintptr_t addr)
 {
-- 
2.19.1