* [PATCH] rs6000: clz/ctz/ffs improvement (PR78683)
@ 2016-12-09 10:37 Segher Boessenkool
2016-12-09 14:53 ` David Edelsohn
0 siblings, 1 reply; 2+ messages in thread
From: Segher Boessenkool @ 2016-12-09 10:37 UTC (permalink / raw)
To: gcc-patches; +Cc: dje.gcc, Segher Boessenkool
On CPUs that implement popcnt[wd] but not cnttz[wd] we can do better for
the ctz sequences than we do today.
CL[TZ]_DEFINED_VALUE_AT_ZERO can return 2, since we always return the
same fixed value (only dependent on TARGET_* options).
I originally tried to have the generic code handle this; that would be
too much surgery for stage 3 though.
Bootstrapped and tested on powerpc64-linux {-m32,-m64}; also tested
manually with {-m32,-m64} -mcpu=power{4,7,9}. Is this okay for trunk?
Segher
2016-12-09 Segher Boessenkool <segher@kernel.crashing.org>
PR target/78683
* config/rs6000/rs6000.h (CLZ_DEFINED_VALUE_AT_ZERO):
Use GET_MODE_BITSIZE. Return 2.
(CTZ_DEFINED_VALUE_AT_ZERO): Use GET_MODE_BITSIZE. Return 2. Handle
TARGET_POPCNTD the same as TARGET_CTZ.
* config/rs6000/rs6000.md (ctz<mode>2): Reimplement.
(ffs<mode>2): Reimplement.
---
gcc/config/rs6000/rs6000.h | 11 ++++----
gcc/config/rs6000/rs6000.md | 62 +++++++++++++++++++++++----------------------
2 files changed, 38 insertions(+), 35 deletions(-)
diff --git a/gcc/config/rs6000/rs6000.h b/gcc/config/rs6000/rs6000.h
index 5d56927..fe314bf 100644
--- a/gcc/config/rs6000/rs6000.h
+++ b/gcc/config/rs6000/rs6000.h
@@ -2199,14 +2199,15 @@ do { \
/* The cntlzw and cntlzd instructions return 32 and 64 for input of zero. */
#define CLZ_DEFINED_VALUE_AT_ZERO(MODE, VALUE) \
- ((VALUE) = ((MODE) == SImode ? 32 : 64), 1)
+ ((VALUE) = GET_MODE_BITSIZE (MODE), 2)
/* The CTZ patterns that are implemented in terms of CLZ return -1 for input of
- zero. The hardware instructions added in Power9 return 32 or 64. */
+ zero. The hardware instructions added in Power9 and the sequences using
+ popcount return 32 or 64. */
#define CTZ_DEFINED_VALUE_AT_ZERO(MODE, VALUE) \
- ((!TARGET_CTZ) \
- ? ((VALUE) = -1, 1) \
- : ((VALUE) = ((MODE) == SImode ? 32 : 64), 1))
+ (TARGET_CTZ || TARGET_POPCNTD \
+ ? ((VALUE) = GET_MODE_BITSIZE (MODE), 2) \
+ : ((VALUE) = -1, 2))
/* Specify the machine mode that pointers have.
After generation of rtl, the compiler makes no further distinction
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index 4726d73..777b996 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -2220,17 +2220,8 @@ (define_insn "clz<mode>2"
[(set_attr "type" "cntlz")])
(define_expand "ctz<mode>2"
- [(set (match_dup 2)
- (neg:GPR (match_operand:GPR 1 "gpc_reg_operand" "")))
- (set (match_dup 3)
- (and:GPR (match_dup 1)
- (match_dup 2)))
- (set (match_dup 4)
- (clz:GPR (match_dup 3)))
- (parallel [(set (match_operand:GPR 0 "gpc_reg_operand" "")
- (minus:GPR (match_dup 5)
- (match_dup 4)))
- (clobber (reg:GPR CA_REGNO))])]
+ [(set (match_operand:GPR 0 "gpc_reg_operand")
+ (ctz:GPR (match_operand:GPR 1 "gpc_reg_operand")))]
""
{
if (TARGET_CTZ)
@@ -2239,10 +2230,26 @@ (define_expand "ctz<mode>2"
DONE;
}
- operands[2] = gen_reg_rtx (<MODE>mode);
- operands[3] = gen_reg_rtx (<MODE>mode);
- operands[4] = gen_reg_rtx (<MODE>mode);
- operands[5] = GEN_INT (GET_MODE_BITSIZE (<MODE>mode) - 1);
+ rtx tmp1 = gen_reg_rtx (<MODE>mode);
+ rtx tmp2 = gen_reg_rtx (<MODE>mode);
+ rtx tmp3 = gen_reg_rtx (<MODE>mode);
+
+ if (TARGET_POPCNTD)
+ {
+ emit_insn (gen_add<mode>3 (tmp1, operands[1], constm1_rtx));
+ emit_insn (gen_one_cmpl<mode>2 (tmp2, operands[1]));
+ emit_insn (gen_and<mode>3 (tmp3, tmp1, tmp2));
+ emit_insn (gen_popcntd<mode>2 (operands[0], tmp3));
+ }
+ else
+ {
+ emit_insn (gen_neg<mode>2 (tmp1, operands[1]));
+ emit_insn (gen_and<mode>3 (tmp2, operands[1], tmp1));
+ emit_insn (gen_clz<mode>2 (tmp3, tmp2));
+ emit_insn (gen_sub<mode>3 (operands[0], GEN_INT (<bits> - 1), tmp3));
+ }
+
+ DONE;
})
(define_insn "ctz<mode>2_hw"
@@ -2253,23 +2260,18 @@ (define_insn "ctz<mode>2_hw"
[(set_attr "type" "cntlz")])
(define_expand "ffs<mode>2"
- [(set (match_dup 2)
- (neg:GPR (match_operand:GPR 1 "gpc_reg_operand" "")))
- (set (match_dup 3)
- (and:GPR (match_dup 1)
- (match_dup 2)))
- (set (match_dup 4)
- (clz:GPR (match_dup 3)))
- (parallel [(set (match_operand:GPR 0 "gpc_reg_operand" "")
- (minus:GPR (match_dup 5)
- (match_dup 4)))
- (clobber (reg:GPR CA_REGNO))])]
+ [(set (match_operand:GPR 0 "gpc_reg_operand")
+ (ffs:GPR (match_operand:GPR 1 "gpc_reg_operand")))]
""
{
- operands[2] = gen_reg_rtx (<MODE>mode);
- operands[3] = gen_reg_rtx (<MODE>mode);
- operands[4] = gen_reg_rtx (<MODE>mode);
- operands[5] = GEN_INT (GET_MODE_BITSIZE (<MODE>mode));
+ rtx tmp1 = gen_reg_rtx (<MODE>mode);
+ rtx tmp2 = gen_reg_rtx (<MODE>mode);
+ rtx tmp3 = gen_reg_rtx (<MODE>mode);
+ emit_insn (gen_neg<mode>2 (tmp1, operands[1]));
+ emit_insn (gen_and<mode>3 (tmp2, operands[1], tmp1));
+ emit_insn (gen_clz<mode>2 (tmp3, tmp2));
+ emit_insn (gen_sub<mode>3 (operands[0], GEN_INT (<bits>), tmp3));
+ DONE;
})
--
1.9.3
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] rs6000: clz/ctz/ffs improvement (PR78683)
2016-12-09 10:37 [PATCH] rs6000: clz/ctz/ffs improvement (PR78683) Segher Boessenkool
@ 2016-12-09 14:53 ` David Edelsohn
0 siblings, 0 replies; 2+ messages in thread
From: David Edelsohn @ 2016-12-09 14:53 UTC (permalink / raw)
To: Segher Boessenkool; +Cc: GCC Patches
On Fri, Dec 9, 2016 at 2:37 AM, Segher Boessenkool
<segher@kernel.crashing.org> wrote:
> On CPUs that implement popcnt[wd] but not cnttz[wd] we can do better for
> the ctz sequences than we do today.
>
> CL[TZ]_DEFINED_VALUE_AT_ZERO can return 2, since we always return the
> same fixed value (only dependent on TARGET_* options).
>
> I originally tried to have the generic code handle this; that would be
> too much surgery for stage 3 though.
>
> Bootstrapped and tested on powerpc64-linux {-m32,-m64}; also tested
> manually with {-m32,-m64} -mcpu=power{4,7,9}. Is this okay for trunk?
>
>
> Segher
>
>
> 2016-12-09 Segher Boessenkool <segher@kernel.crashing.org>
>
> PR target/78683
> * config/rs6000/rs6000.h (CLZ_DEFINED_VALUE_AT_ZERO):
> Use GET_MODE_BITSIZE. Return 2.
> (CTZ_DEFINED_VALUE_AT_ZERO): Use GET_MODE_BITSIZE. Return 2. Handle
> TARGET_POPCNTD the same as TARGET_CTZ.
> * config/rs6000/rs6000.md (ctz<mode>2): Reimplement.
> (ffs<mode>2): Reimplement.
Okay.
Thanks, David
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2016-12-09 14:53 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-12-09 10:37 [PATCH] rs6000: clz/ctz/ffs improvement (PR78683) Segher Boessenkool
2016-12-09 14:53 ` David Edelsohn
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).