Messages in this thread | | | Subject | Re: [PATCH 2/2] powerpc: cleanup hw_irq.h | From | Christophe Leroy <> | Date | Tue, 27 Aug 2019 20:33:45 +0200 |
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Le 27/08/2019 à 20:26, Segher Boessenkool a écrit : > On Tue, Aug 27, 2019 at 07:36:35PM +0200, Christophe Leroy wrote: >> Le 27/08/2019 à 19:29, Segher Boessenkool a écrit : >>> On Tue, Aug 27, 2019 at 10:48:24PM +1000, Nicholas Piggin wrote: >>>> Christophe Leroy's on August 27, 2019 6:13 pm: >>>>> +#define wrtee(val) asm volatile("wrtee %0" : : "r" (val) : "memory") >>>>> +#define wrteei(val) asm volatile("wrteei %0" : : "i" (val) : >>>>> "memory") >>>> >>>> Can you implement just one macro that uses __builtin_constant_p to >>>> select between the imm and reg versions? I forgot if there's some >>>> corner cases that prevent that working with inline asm i constraints. >>> >>> static inline void wrtee(long val) >>> { >>> asm volatile("wrtee%I0 %0" : : "n"(val) : "memory"); >>> } >> >> Great, didn't know that possibility. >> >> Can it be used with any insn, for instance with add/addi ? >> Or with mr/li ? > > Any instruction, yes. %I<n> simply outputs an "i" if operand n is a > constant integer, and nothing otherwise.
Thinking about it once more, I'm not sure this form is possible, because wrteei expect 0 or 1. If someone calls wrtee(MSR_EE); (or any constant containing MSR_EE) wrteei 1 is expected. And any constant with MSR_EE cleared should result in wrteei 0.
> > So > asm("add%I2 %0,%1,%2" : "=r"(dst) : "r"(src1), "ri"(src1));
"ri", not "n" as for wrtee ?
Christophe
> works well. I don't see how you would use it for li/mr... You can do > asm("add%I1 %0,0,%1" : "=r"(dst) : "ri"(src)); > I suppose, but that is not really an mr. > >>> (This output modifier goes back to the dark ages, some 2.4 or something). >> >> Hope Clang support it ... > > I don't know, sorry. But it is used all over the place, see sfp-machine.h > for example, so maybe? > > > Segher >
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