From: Segher Boessenkool <segher@kernel.crashing.org> To: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Paul Mackerras <paulus@samba.org>, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v1 2/2] powerpc/atomics: Use immediate operand when possible Date: Mon, 12 Apr 2021 17:08:22 -0500 [thread overview] Message-ID: <20210412220821.GN26583@gate.crashing.org> (raw) In-Reply-To: <9f50b5fadeb090553e5c2fae025052d04d52f3c7.1617896018.git.christophe.leroy@csgroup.eu> Hi! On Thu, Apr 08, 2021 at 03:33:45PM +0000, Christophe Leroy wrote: > +#define ATOMIC_OP(op, asm_op, dot, sign) \ > static __inline__ void atomic_##op(int a, atomic_t *v) \ > { \ > int t; \ > \ > __asm__ __volatile__( \ > "1: lwarx %0,0,%3 # atomic_" #op "\n" \ > - #asm_op " %0,%2,%0\n" \ > + #asm_op "%I2" dot " %0,%0,%2\n" \ > " stwcx. %0,0,%3 \n" \ > " bne- 1b\n" \ > - : "=&r" (t), "+m" (v->counter) \ > - : "r" (a), "r" (&v->counter) \ > + : "=&b" (t), "+m" (v->counter) \ > + : "r"#sign (a), "r" (&v->counter) \ > : "cc"); \ > } \ You need "b" (instead of "r") only for "addi". You can use "addic" instead, which clobbers XER[CA], but *all* inline asm does, so that is not a downside here (it is also not slower on any CPU that matters). > @@ -238,14 +238,14 @@ static __inline__ int atomic_fetch_add_unless(atomic_t *v, int a, int u) > "1: lwarx %0,0,%1 # atomic_fetch_add_unless\n\ > cmpw 0,%0,%3 \n\ > beq 2f \n\ > - add %0,%2,%0 \n" > + add%I2 %0,%0,%2 \n" > " stwcx. %0,0,%1 \n\ > bne- 1b \n" > PPC_ATOMIC_EXIT_BARRIER > -" subf %0,%2,%0 \n\ > +" sub%I2 %0,%0,%2 \n\ > 2:" > - : "=&r" (t) > - : "r" (&v->counter), "r" (a), "r" (u) > + : "=&b" (t) > + : "r" (&v->counter), "rI" (a), "r" (u) > : "cc", "memory"); Same here. Nice patches! Acked-by: Segher Boessenkool <segher@kernel.crashing.org> Segher
WARNING: multiple messages have this Message-ID (diff)
From: Segher Boessenkool <segher@kernel.crashing.org> To: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>, Paul Mackerras <paulus@samba.org>, Michael Ellerman <mpe@ellerman.id.au>, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v1 2/2] powerpc/atomics: Use immediate operand when possible Date: Mon, 12 Apr 2021 17:08:22 -0500 [thread overview] Message-ID: <20210412220821.GN26583@gate.crashing.org> (raw) In-Reply-To: <9f50b5fadeb090553e5c2fae025052d04d52f3c7.1617896018.git.christophe.leroy@csgroup.eu> Hi! On Thu, Apr 08, 2021 at 03:33:45PM +0000, Christophe Leroy wrote: > +#define ATOMIC_OP(op, asm_op, dot, sign) \ > static __inline__ void atomic_##op(int a, atomic_t *v) \ > { \ > int t; \ > \ > __asm__ __volatile__( \ > "1: lwarx %0,0,%3 # atomic_" #op "\n" \ > - #asm_op " %0,%2,%0\n" \ > + #asm_op "%I2" dot " %0,%0,%2\n" \ > " stwcx. %0,0,%3 \n" \ > " bne- 1b\n" \ > - : "=&r" (t), "+m" (v->counter) \ > - : "r" (a), "r" (&v->counter) \ > + : "=&b" (t), "+m" (v->counter) \ > + : "r"#sign (a), "r" (&v->counter) \ > : "cc"); \ > } \ You need "b" (instead of "r") only for "addi". You can use "addic" instead, which clobbers XER[CA], but *all* inline asm does, so that is not a downside here (it is also not slower on any CPU that matters). > @@ -238,14 +238,14 @@ static __inline__ int atomic_fetch_add_unless(atomic_t *v, int a, int u) > "1: lwarx %0,0,%1 # atomic_fetch_add_unless\n\ > cmpw 0,%0,%3 \n\ > beq 2f \n\ > - add %0,%2,%0 \n" > + add%I2 %0,%0,%2 \n" > " stwcx. %0,0,%1 \n\ > bne- 1b \n" > PPC_ATOMIC_EXIT_BARRIER > -" subf %0,%2,%0 \n\ > +" sub%I2 %0,%0,%2 \n\ > 2:" > - : "=&r" (t) > - : "r" (&v->counter), "r" (a), "r" (u) > + : "=&b" (t) > + : "r" (&v->counter), "rI" (a), "r" (u) > : "cc", "memory"); Same here. Nice patches! Acked-by: Segher Boessenkool <segher@kernel.crashing.org> Segher
next prev parent reply other threads:[~2021-04-12 22:11 UTC|newest] Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-04-08 15:33 [PATCH v1 1/2] powerpc/bitops: Use immediate operand when possible Christophe Leroy 2021-04-08 15:33 ` Christophe Leroy 2021-04-08 15:33 ` [PATCH v1 2/2] powerpc/atomics: " Christophe Leroy 2021-04-08 15:33 ` Christophe Leroy 2021-04-12 22:08 ` Segher Boessenkool [this message] 2021-04-12 22:08 ` Segher Boessenkool 2021-04-13 16:36 ` Christophe Leroy 2021-04-13 16:36 ` Christophe Leroy 2021-04-12 21:54 ` [PATCH v1 1/2] powerpc/bitops: " Segher Boessenkool 2021-04-12 21:54 ` Segher Boessenkool 2021-04-13 16:33 ` Christophe Leroy 2021-04-13 16:33 ` Christophe Leroy 2021-04-13 21:58 ` Segher Boessenkool 2021-04-13 21:58 ` Segher Boessenkool 2021-04-14 2:01 ` Nicholas Piggin 2021-04-14 2:01 ` Nicholas Piggin 2021-04-14 12:24 ` Segher Boessenkool 2021-04-14 12:24 ` Segher Boessenkool 2021-04-14 12:42 ` Christophe Leroy 2021-04-14 12:42 ` Christophe Leroy 2021-04-14 15:19 ` Segher Boessenkool 2021-04-14 15:19 ` Segher Boessenkool 2021-04-14 15:32 ` David Laight 2021-04-14 15:32 ` David Laight 2021-04-14 17:20 ` Segher Boessenkool 2021-04-14 17:20 ` Segher Boessenkool
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