| Message ID | 1364876610-3933-18-git-send-email-rth@twiddle.net |
|---|---|
| State | New |
| Headers | show |
On 02.04.2013, at 06:23, Richard Henderson wrote: > Reviewed-by: Aurelien Jarno <aurelien@aurel32.net> > Signed-off-by: Richard Henderson <rth@twiddle.net> Is this faster than a load/store with std/ldbrx? Alex > --- > tcg/ppc64/tcg-target.c | 35 +++++++++++++++++++++++++++++++++++ > tcg/ppc64/tcg-target.h | 2 +- > 2 files changed, 36 insertions(+), 1 deletion(-) > > diff --git a/tcg/ppc64/tcg-target.c b/tcg/ppc64/tcg-target.c > index d8131ec..1806364 100644 > --- a/tcg/ppc64/tcg-target.c > +++ b/tcg/ppc64/tcg-target.c > @@ -1706,6 +1706,40 @@ static void tcg_out_op (TCGContext *s, TCGOpcode opc, const TCGArg *args, > } > break; > > + case INDEX_op_bswap64_i64: > + a0 = args[0], a1 = args[1], a2 = 0; > + if (a0 == a1) { > + a0 = 0; > + a2 = a1; > + } > + > + /* a1 = # abcd efgh */ > + /* a0 = rl32(a1, 8) # 0000 fghe */ > + tcg_out_rlw(s, RLWINM, a0, a1, 8, 0, 31); > + /* a0 = dep(a0, rl32(a1, 24), 0xff000000) # 0000 hghe */ > + tcg_out_rlw(s, RLWIMI, a0, a1, 24, 0, 7); > + /* a0 = dep(a0, rl32(a1, 24), 0x0000ff00) # 0000 hgfe */ > + tcg_out_rlw(s, RLWIMI, a0, a1, 24, 16, 23); > + > + /* a0 = rl64(a0, 32) # hgfe 0000 */ > + /* a2 = rl64(a1, 32) # efgh abcd */ > + tcg_out_rld(s, RLDICL, a0, a0, 32, 0); > + tcg_out_rld(s, RLDICL, a2, a1, 32, 0); > + > + /* a0 = dep(a0, rl32(a2, 8), 0xffffffff) # hgfe bcda */ > + tcg_out_rlw(s, RLWIMI, a0, a2, 8, 0, 31); > + /* a0 = dep(a0, rl32(a2, 24), 0xff000000) # hgfe dcda */ > + tcg_out_rlw(s, RLWIMI, a0, a2, 24, 0, 7); > + /* a0 = dep(a0, rl32(a2, 24), 0x0000ff00) # hgfe dcba */ > + tcg_out_rlw(s, RLWIMI, a0, a2, 24, 16, 23); > + > + if (a0 == 0) { > + tcg_out_mov(s, TCG_TYPE_I64, args[0], a0); > + /* Revert the source rotate that we performed above. */ > + tcg_out_rld(s, RLDICL, a1, a1, 32, 0); > + } > + break; > + > default: > tcg_dump_ops (s); > tcg_abort (); > @@ -1816,6 +1850,7 @@ static const TCGTargetOpDef ppc_op_defs[] = { > { INDEX_op_bswap16_i64, { "r", "r" } }, > { INDEX_op_bswap32_i32, { "r", "r" } }, > { INDEX_op_bswap32_i64, { "r", "r" } }, > + { INDEX_op_bswap64_i64, { "r", "r" } }, > > { -1 }, > }; > diff --git a/tcg/ppc64/tcg-target.h b/tcg/ppc64/tcg-target.h > index bd011b8..d8e1820 100644 > --- a/tcg/ppc64/tcg-target.h > +++ b/tcg/ppc64/tcg-target.h > @@ -102,7 +102,7 @@ typedef enum { > #define TCG_TARGET_HAS_ext32u_i64 1 > #define TCG_TARGET_HAS_bswap16_i64 1 > #define TCG_TARGET_HAS_bswap32_i64 1 > -#define TCG_TARGET_HAS_bswap64_i64 0 > +#define TCG_TARGET_HAS_bswap64_i64 1 > #define TCG_TARGET_HAS_not_i64 1 > #define TCG_TARGET_HAS_neg_i64 1 > #define TCG_TARGET_HAS_andc_i64 0 > -- > 1.8.1.4 >
On 2013-04-01 23:34, Alexander Graf wrote:
> Is this faster than a load/store with std/ldbrx?
Hmm. Almost certainly not. And since we've got stack space
allocated for function calls, we've got scratch space to do it in.
Probably similar for bswap32 too, eh?
I'll do a tiny bit o benchmarking for power7.
r~
Am 02.04.2013 um 15:44 schrieb Richard Henderson <rth@twiddle.net>: > On 2013-04-01 23:34, Alexander Graf wrote: >> Is this faster than a load/store with std/ldbrx? > > Hmm. Almost certainly not. And since we've got stack space > allocated for function calls, we've got scratch space to do it in. > > Probably similar for bswap32 too, eh? Depends - memory load/store doesn't come for free and bswap32 is quite short. > > I'll do a tiny bit o benchmarking for power7. Cool, thanks a bunch :) Alex > > > r~
On 2013-04-02 07:41, Alexander Graf wrote: >> On 2013-04-01 23:34, Alexander Graf wrote: >>> Is this faster than a load/store with std/ldbrx? >> >> Hmm. Almost certainly not. And since we've got stack space >> allocated for function calls, we've got scratch space to do it in. >> >> Probably similar for bswap32 too, eh? > > Depends - memory load/store doesn't come for free and bswap32 is quite short. > >> >> I'll do a tiny bit o benchmarking for power7. > > Cool, thanks a bunch :) Heh. "Almost certainly not" indeed. Unless I've made some silly mistake, going through memory stalls badly. No store buffer forwarding on power7? With the following test case, time reports: f1 2.967s f2 8.930s f3 7.071s f4 7.166s And note that f4 is a normal store/load pair, trying to determine what the store buffer forwarding delay might be. r~
On 04/02/2013 05:12 PM, Richard Henderson wrote: > On 2013-04-02 07:41, Alexander Graf wrote: >>> On 2013-04-01 23:34, Alexander Graf wrote: >>>> Is this faster than a load/store with std/ldbrx? >>> >>> Hmm. Almost certainly not. And since we've got stack space >>> allocated for function calls, we've got scratch space to do it in. >>> >>> Probably similar for bswap32 too, eh? >> >> Depends - memory load/store doesn't come for free and bswap32 is >> quite short. >> >>> >>> I'll do a tiny bit o benchmarking for power7. >> >> Cool, thanks a bunch :) > > Heh. "Almost certainly not" indeed. Unless I've made some silly > mistake, > going through memory stalls badly. No store buffer forwarding on power7? > > With the following test case, time reports: > > f1 2.967s > f2 8.930s > f3 7.071s > f4 7.166s > > And note that f4 is a normal store/load pair, trying to determine what > the > store buffer forwarding delay might be. Yeah, doesn't look like it makes any sense at all to do a load/store cycle then. What a shame :). Keep in mind that this tests icache hot cycles. However, you might get bad icache penalties due to the long bswap64 sequence. So all the memory latency you see here might also affect the instruction stream when it gets executed. But then again we only care about performance of cache hot sequences in the first place.... Alex
diff --git a/tcg/ppc64/tcg-target.c b/tcg/ppc64/tcg-target.c index d8131ec..1806364 100644 --- a/tcg/ppc64/tcg-target.c +++ b/tcg/ppc64/tcg-target.c @@ -1706,6 +1706,40 @@ static void tcg_out_op (TCGContext *s, TCGOpcode opc, const TCGArg *args, } break; + case INDEX_op_bswap64_i64: + a0 = args[0], a1 = args[1], a2 = 0; + if (a0 == a1) { + a0 = 0; + a2 = a1; + } + + /* a1 = # abcd efgh */ + /* a0 = rl32(a1, 8) # 0000 fghe */ + tcg_out_rlw(s, RLWINM, a0, a1, 8, 0, 31); + /* a0 = dep(a0, rl32(a1, 24), 0xff000000) # 0000 hghe */ + tcg_out_rlw(s, RLWIMI, a0, a1, 24, 0, 7); + /* a0 = dep(a0, rl32(a1, 24), 0x0000ff00) # 0000 hgfe */ + tcg_out_rlw(s, RLWIMI, a0, a1, 24, 16, 23); + + /* a0 = rl64(a0, 32) # hgfe 0000 */ + /* a2 = rl64(a1, 32) # efgh abcd */ + tcg_out_rld(s, RLDICL, a0, a0, 32, 0); + tcg_out_rld(s, RLDICL, a2, a1, 32, 0); + + /* a0 = dep(a0, rl32(a2, 8), 0xffffffff) # hgfe bcda */ + tcg_out_rlw(s, RLWIMI, a0, a2, 8, 0, 31); + /* a0 = dep(a0, rl32(a2, 24), 0xff000000) # hgfe dcda */ + tcg_out_rlw(s, RLWIMI, a0, a2, 24, 0, 7); + /* a0 = dep(a0, rl32(a2, 24), 0x0000ff00) # hgfe dcba */ + tcg_out_rlw(s, RLWIMI, a0, a2, 24, 16, 23); + + if (a0 == 0) { + tcg_out_mov(s, TCG_TYPE_I64, args[0], a0); + /* Revert the source rotate that we performed above. */ + tcg_out_rld(s, RLDICL, a1, a1, 32, 0); + } + break; + default: tcg_dump_ops (s); tcg_abort (); @@ -1816,6 +1850,7 @@ static const TCGTargetOpDef ppc_op_defs[] = { { INDEX_op_bswap16_i64, { "r", "r" } }, { INDEX_op_bswap32_i32, { "r", "r" } }, { INDEX_op_bswap32_i64, { "r", "r" } }, + { INDEX_op_bswap64_i64, { "r", "r" } }, { -1 }, }; diff --git a/tcg/ppc64/tcg-target.h b/tcg/ppc64/tcg-target.h index bd011b8..d8e1820 100644 --- a/tcg/ppc64/tcg-target.h +++ b/tcg/ppc64/tcg-target.h @@ -102,7 +102,7 @@ typedef enum { #define TCG_TARGET_HAS_ext32u_i64 1 #define TCG_TARGET_HAS_bswap16_i64 1 #define TCG_TARGET_HAS_bswap32_i64 1 -#define TCG_TARGET_HAS_bswap64_i64 0 +#define TCG_TARGET_HAS_bswap64_i64 1 #define TCG_TARGET_HAS_not_i64 1 #define TCG_TARGET_HAS_neg_i64 1 #define TCG_TARGET_HAS_andc_i64 0