Commit 43b3952d authored by Richard Henderson's avatar Richard Henderson
Browse files

tcg/arm: Remove mostly unreachable tlb special case 



There was nothing armv7 specific about the bic+cmp sequence, however
looking at the set of guests more closely shows that the 8-bit immediate
operand for the bic can only be satisfied with one guest in tree:
baseline m-profile -- 10-bit pages with aligned 4-byte memory ops.
Therefore it does not seem useful to keep this path.

Acked-by: default avatarAlistair Francis <alistair.francis@wdc.com>
Signed-off-by: default avatarRichard Henderson <richard.henderson@linaro.org>
parent 057b6e37

tcg/arm/tcg-target.inc.c

+12 −11
Original line number Diff line number Diff line
@@ -1290,19 +1290,20 @@ static TCGReg tcg_out_tlb_read(TCGContext *s, TCGReg addrlo, TCGReg addrhi, 
    tcg_out_ld32_12(s, COND_AL, TCG_REG_R1, TCG_REG_R1,

                    offsetof(CPUTLBEntry, addend));



    /* Check alignment, check comparators.  */

    if (use_armv7_instructions) {

    /*

     * Check alignment, check comparators.

     * Do this in no more than 3 insns.  Use MOVW for v7, if possible,

     * to reduce the number of sequential conditional instructions.

     * Almost all guests have at least 4k pages, which means that we need

     * to clear at least 9 bits even for an 8-byte memory, which means it

     * isn't worth checking for an immediate operand for BIC.

     */

    if (use_armv7_instructions && TARGET_PAGE_BITS <= 16) {

        tcg_target_ulong mask = ~(TARGET_PAGE_MASK | ((1 << a_bits) - 1));

        int rot = encode_imm(mask);



        if (rot >= 0) { 

            tcg_out_dat_imm(s, COND_AL, ARITH_BIC, TCG_REG_TMP, addrlo,

                            rotl(mask, rot) | (rot << 7));

        } else {

        tcg_out_movi32(s, COND_AL, TCG_REG_TMP, mask);

        tcg_out_dat_reg(s, COND_AL, ARITH_BIC, TCG_REG_TMP,

                        addrlo, TCG_REG_TMP, 0);

        }

        tcg_out_dat_reg(s, COND_AL, ARITH_CMP, 0, TCG_REG_R2, TCG_REG_TMP, 0);

    } else {

        if (a_bits) {