Commit 23b7aa1d authored by Pranith Kumar's avatar Pranith Kumar Committed by Richard Henderson
Browse files

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.

CC: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: default avatarRichard Henderson <rth@twiddle.net>
Signed-off-by: default avatarPranith Kumar <bobby.prani@gmail.com>
Message-Id: <20170630143614.31059-1-bobby.prani@gmail.com>
Signed-off-by: default avatarRichard Henderson <rth@twiddle.net>
parent b1136586

tcg/aarch64/tcg-target.inc.c

+13 −2
Original line number Diff line number Diff line
@@ -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;