diff options
| author | Richard Henderson <richard.henderson@linaro.org> | 2019-05-07 10:33:44 -0700 |
|---|---|---|
| committer | Richard Henderson <richard.henderson@linaro.org> | 2019-06-10 07:03:42 -0700 |
| commit | 43b3952dea0f763ceeaa2f119c473b5cc6d29c90 (patch) | |
| tree | 90697278e6aefd0b91858c403ddb5670f6bdf053 /tcg | |
| parent | 057b6e370b0947613b0e829c0bb0ddf960003d15 (diff) | |
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: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Diffstat (limited to 'tcg')
| -rw-r--r-- | tcg/arm/tcg-target.inc.c | 23 |
1 files changed, 12 insertions, 11 deletions
diff --git a/tcg/arm/tcg-target.inc.c b/tcg/arm/tcg-target.inc.c index 276e843627..ece88dc2eb 100644 --- a/tcg/arm/tcg-target.inc.c +++ b/tcg/arm/tcg-target.inc.c @@ -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_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) { |