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Re: [Qemu-devel] [PATCH 04/11] target-mips: convert bitfield ops to TCG
From: |
Aurelien Jarno |
Subject: |
Re: [Qemu-devel] [PATCH 04/11] target-mips: convert bitfield ops to TCG |
Date: |
Sat, 8 Nov 2008 20:13:23 +0100 |
User-agent: |
Mutt/1.5.18 (2008-05-17) |
On Sat, Nov 08, 2008 at 01:57:21PM +0100, Laurent Desnogues wrote:
> On Sat, Nov 8, 2008 at 9:34 AM, Aurelien Jarno <address@hidden> wrote:
> > Bitfield operations can be written with very few TCG instructions
> > (between 2 and 5), so it is worth converting them to TCG.
> >
> > Signed-off-by: Aurelien Jarno <address@hidden>
> > ---
> > target-mips/helper.h | 6 +----
> > target-mips/op_helper.c | 26 +------------------------
> > target-mips/translate.c | 49
> > +++++++++++++++++++++++++++++++++++++---------
> > 3 files changed, 41 insertions(+), 40 deletions(-)
> [...]
> > diff --git a/target-mips/translate.c b/target-mips/translate.c
> > index af01f73..2cd1868 100644
> > --- a/target-mips/translate.c
> > +++ b/target-mips/translate.c
> > @@ -2682,57 +2682,86 @@ static void gen_compute_branch (DisasContext *ctx,
> > uint32_t opc,
> > static void gen_bitops (DisasContext *ctx, uint32_t opc, int rt,
> > int rs, int lsb, int msb)
> > {
> > - TCGv t0 = tcg_temp_local_new(TCG_TYPE_TL);
> > - TCGv t1 = tcg_temp_local_new(TCG_TYPE_TL);
> > + TCGv t0 = tcg_temp_new(TCG_TYPE_TL);
> > + TCGv t1 = tcg_temp_new(TCG_TYPE_TL);
> > + target_ulong mask;
> >
> > gen_load_gpr(t1, rs);
> > switch (opc) {
> > case OPC_EXT:
> > if (lsb + msb > 31)
> > goto fail;
> > - tcg_gen_helper_1_1ii(do_ext, t0, t1, lsb, msb + 1);
> > + tcg_gen_shri_tl(t0, t1, lsb);
> > + if (msb + 1 < 32) {
>
> Given the above restriction of lsb + msb <= 31, this test can
> be rewritten as:
>
> if (msb != 31)
>
> I find this more readable, but that's personal taste :-)
Fixed.
> > + tcg_gen_andi_tl(t0, t0, (1 << (msb + 1)) - 1);
> > + } else {
> > + tcg_gen_ext32s_tl(t0, t0);
> > + }
> > break;
> > #if defined(TARGET_MIPS64)
> > case OPC_DEXTM:
> > if (lsb + msb > 63)
> > goto fail;
>
> Can this really happen? lsb and msb are 5 bit wide as far
> as I could see.
Not it can't. It comes for the previous code, and I forget to "optimize"
this part.
> > - tcg_gen_helper_1_1ii(do_dext, t0, t1, lsb, msb + 1 + 32);
> > + tcg_gen_shri_tl(t0, t1, lsb);
> > + if (msb + 1 + 32 < 64) {
>
> This can be rewritten as
>
> if (msb != 31)
Fixed.
> > + tcg_gen_andi_tl(t0, t0, (1ULL << (msb + 1 + 32)) - 1);
> > + }
> > break;
> > case OPC_DEXTU:
> > if (lsb + msb > 63)
> > goto fail;
>
> Same as above.
Fixed.
> > - tcg_gen_helper_1_1ii(do_dext, t0, t1, lsb + 32, msb + 1);
> > + tcg_gen_shri_tl(t0, t1, lsb + 32);
> > + tcg_gen_andi_tl(t0, t0, (1ULL << (msb + 1)) - 1);
> > break;
> > case OPC_DEXT:
> > if (lsb + msb > 63)
> > goto fail;
>
> Same as above.
>
Fixed.
>
> Laurent
>
>
>
--
.''`. Aurelien Jarno | GPG: 1024D/F1BCDB73
: :' : Debian developer | Electrical Engineer
`. `' address@hidden | address@hidden
`- people.debian.org/~aurel32 | www.aurel32.net
- [Qemu-devel] [PATCH 0/11] target-mips: optimizations, Aurelien Jarno, 2008/11/08
- [Qemu-devel] [PATCH 01/11] target-mips: optimize gen_save_pc(), Aurelien Jarno, 2008/11/08
- [Qemu-devel] [PATCH 02/11] target-mips: optimize gen_op_addr_add() (1/2), Aurelien Jarno, 2008/11/08
- [Qemu-devel] [PATCH 03/11] target-mips: optimize gen_op_addr_add() (2/2), Aurelien Jarno, 2008/11/08
- [Qemu-devel] [PATCH 04/11] target-mips: convert bitfield ops to TCG, Aurelien Jarno, 2008/11/08
- [Qemu-devel] [PATCH 05/11] target-mips: convert bit shuffle ops to TCG, Aurelien Jarno, 2008/11/08
- [Qemu-devel] [PATCH 06/11] target-mips: optimize gen_arith()/gen_arith_imm(), Aurelien Jarno, 2008/11/08
- [Qemu-devel] [PATCH 07/11] target-mips: optimize gen_muldiv(), Aurelien Jarno, 2008/11/08
- [Qemu-devel] [PATCH 08/11] target-mips: optimize gen_farith(), Aurelien Jarno, 2008/11/08
- [Qemu-devel] [PATCH 09/11] target-mips: optimize movc*(), Aurelien Jarno, 2008/11/08
- [Qemu-devel] [PATCH 10/11] target-mips: gen_compute_branch1(), Aurelien Jarno, 2008/11/08
- [Qemu-devel] [PATCH 11/11] target-mips: fix temporary variable freeing in op_ldst_##insn(), Aurelien Jarno, 2008/11/08