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tcg/aarch64: Introduce and use long branch to register

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

CC: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Message-Id: <20170630143614.31059-1-bobby.prani@gmail.com>
Signed-off-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Pranith Kumar 2017-06-30 10:36:12 -04:00 committed by Richard Henderson
parent b113658675
commit 23b7aa1d2a
1 changed files with 13 additions and 2 deletions
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15
tcg/aarch64/tcg-target.inc.c
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@ -819,6 +819,17 @@ 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
@ -1364,10 +1375,10 @@ 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;