Commit eb02cc3f authored by Aurelien Jarno's avatar Aurelien Jarno Committed by Leon Alrae
Browse files

target-mips: simplify LWL/LDL mask generation 



The LWL/LDL instructions mask the GPR with a mask depending on the
address alignement. It is currently computed by doing:

    mask = 0x7fffffffffffffffull >> (t1 ^ 63)

It's simpler to generate it by doing:

    mask = ~(-1 << t1)

It uses one TCG instruction less, and it avoids a 32/64-bit constant
loading which can take a few instructions on RISC hosts.

Cc: Leon Alrae <leon.alrae@imgtec.com>
Signed-off-by: default avatarAurelien Jarno <aurelien@aurel32.net>
Reviewed-by: default avatarRichard Henderson <rth@twiddle.net>
Reviewed-by: default avatarLeon Alrae <leon.alrae@imgtec.com>
Signed-off-by: default avatarLeon Alrae <leon.alrae@imgtec.com>
parent aff2bc6d

target-mips/translate.c

+6 −8
Original line number Diff line number Diff line
@@ -2153,11 +2153,10 @@ static void gen_ld(DisasContext *ctx, uint32_t opc, 
        tcg_gen_andi_tl(t0, t0, ~7);

        tcg_gen_qemu_ld_tl(t0, t0, ctx->mem_idx, MO_TEQ);

        tcg_gen_shl_tl(t0, t0, t1);

        tcg_gen_xori_tl(t1, t1, 63);

        t2 = tcg_const_tl(0x7fffffffffffffffull);

        tcg_gen_shr_tl(t2, t2, t1);

        t2 = tcg_const_tl(-1);

        tcg_gen_shl_tl(t2, t2, t1);

        gen_load_gpr(t1, rt);

        tcg_gen_and_tl(t1, t1, t2);

        tcg_gen_andc_tl(t1, t1, t2);

        tcg_temp_free(t2);

        tcg_gen_or_tl(t0, t0, t1);

        tcg_temp_free(t1);
@@ -2246,11 +2245,10 @@ static void gen_ld(DisasContext *ctx, uint32_t opc, 
        tcg_gen_andi_tl(t0, t0, ~3);

        tcg_gen_qemu_ld_tl(t0, t0, ctx->mem_idx, MO_TEUL);

        tcg_gen_shl_tl(t0, t0, t1);

        tcg_gen_xori_tl(t1, t1, 31);

        t2 = tcg_const_tl(0x7fffffffull);

        tcg_gen_shr_tl(t2, t2, t1);

        t2 = tcg_const_tl(-1);

        tcg_gen_shl_tl(t2, t2, t1);

        gen_load_gpr(t1, rt);

        tcg_gen_and_tl(t1, t1, t2);

        tcg_gen_andc_tl(t1, t1, t2);

        tcg_temp_free(t2);

        tcg_gen_or_tl(t0, t0, t1);

        tcg_temp_free(t1);