tcg/aarch64: Introduce and use long branch to register

We can use a branch to register instruction for exit_tb for offsets
greater than 128MB.

Backports commit 23b7aa1d2af04ba57cc94f74d9f0ab25dce72fa0 from qemu
This commit is contained in:
Pranith Kumar 2018-03-03 21:59:52 -05:00 committed by Lioncash
parent 1e0745b31a
commit 0998ba8259
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@ -823,6 +823,17 @@ static inline void tcg_out_goto(TCGContext *s, tcg_insn_unit *target)
tcg_out_insn(s, 3206, B, offset);
}
static inline void tcg_out_goto_long(TCGContext *s, tcg_insn_unit *target)
{
ptrdiff_t offset = target - s->code_ptr;
if (offset == sextract64(offset, 0, 26)) {
tcg_out_insn(s, 3206, BL, offset);
} else {
tcg_out_movi(s, TCG_TYPE_I64, TCG_REG_TMP, (intptr_t)target);
tcg_out_insn(s, 3207, BR, TCG_REG_TMP);
}
}
static inline void tcg_out_goto_noaddr(TCGContext *s)
{
/* We pay attention here to not modify the branch target by reading from
@ -1379,10 +1390,10 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc,
case INDEX_op_exit_tb:
/* Reuse the zeroing that exists for goto_ptr. */
if (a0 == 0) {
tcg_out_goto(s, s->code_gen_epilogue);
tcg_out_goto_long(s, s->code_gen_epilogue);
} else {
tcg_out_movi(s, TCG_TYPE_I64, TCG_REG_X0, a0);
tcg_out_goto(s, tb_ret_addr);
tcg_out_goto_long(s, tb_ret_addr);
}
break;