linux-kernel - Re: [PATCH] powerpc/xmon: replace sizeof calculations with ARRAY

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Message-ID: <8381a142d72f3cd0e92de4dac6acfc0241a87365.camel@aol.com>
Date: Thu, 31 Jul 2025 17:40:05 +0100
From: Ruben Wauters <rubenru09@....com>
To: Christophe Leroy <christophe.leroy@...roup.eu>, Madhavan Srinivasan	
 <maddy@...ux.ibm.com>, Michael Ellerman <mpe@...erman.id.au>, Nicholas
 Piggin	 <npiggin@...il.com>
Cc: linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org, 
	kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] powerpc/xmon: replace sizeof calculations with
 ARRAY_SIZE macro

On Wed, 2025-07-30 at 08:14 +0200, Christophe Leroy wrote:
> 
> 
> Le 20/07/2025 à 00:43, Ruben Wauters a écrit :
> > [Vous ne recevez pas souvent de courriers de rubenru09@....com.
> > Découvrez pourquoi ceci est important à
> > https://aka.ms/LearnAboutSenderIdentification ]
> > 
> > The calculations for operand/opcode/macro numbers are done in an
> > identical manner to the already existing ARRAY_SIZE macro in
> > linux/array_size.h
> > 
> > This patch replaces the sizeof calculations with the macro to make
> > the
> > code cleaner and more immediately obvious what it is doing.
> > 
> > Signed-off-by: Ruben Wauters <rubenru09@....com>
> > ---
> >   arch/powerpc/xmon/ppc-opc.c | 16 ++++++----------
> 
> This file is mostly taken from binutils, refer commit 08d96e0b127e 
> ("powerpc/xmon: Apply binutils changes to upgrade disassembly").
> 
> I think your change should be done in binutils then backported to the
> kernel. The more we diverge from binutils the worse it is

While this is somewhat reasonable, the header (linux/array_size.h) is
linux specific, and is included through kernel.h

I can probably see if binutils has a similar header, or if they would
accept an equivalent header to make the file equivalent, but I'm unsure
if they would

Ruben

> Christophe
> 
> 
> >   1 file changed, 6 insertions(+), 10 deletions(-)
> > 
> > diff --git a/arch/powerpc/xmon/ppc-opc.c b/arch/powerpc/xmon/ppc-
> > opc.c
> > index 0774d711453e..de9b4236728c 100644
> > --- a/arch/powerpc/xmon/ppc-opc.c
> > +++ b/arch/powerpc/xmon/ppc-opc.c
> > @@ -954,8 +954,7 @@ const struct powerpc_operand powerpc_operands[]
> > =
> >     { 0xff, 11, NULL, NULL, PPC_OPERAND_SIGNOPT },
> >   };
> > 
> > -const unsigned int num_powerpc_operands = (sizeof
> > (powerpc_operands)
> > -                                          / sizeof
> > (powerpc_operands[0]));
> > +const unsigned int num_powerpc_operands =
> > ARRAY_SIZE(powerpc_operands);
> > 
> >   /* The functions used to insert and extract complicated
> > operands.  */
> > 
> > @@ -6968,9 +6967,8 @@ const struct powerpc_opcode powerpc_opcodes[]
> > = {
> >   {"fcfidu.",    XRC(63,974,1),  XRA_MASK, POWER7|PPCA2,
> > PPCVLE,         {FRT, FRB}},
> >   };
> > 
> > -const int powerpc_num_opcodes =
> > -  sizeof (powerpc_opcodes) / sizeof (powerpc_opcodes[0]);
> > -
> > +const int powerpc_num_opcodes = ARRAY_SIZE(powerpc_opcodes);
> > +
> >   /* The VLE opcode table.
> > 
> >      The format of this opcode table is the same as the main opcode
> > table.  */
> > @@ -7207,9 +7205,8 @@ const struct powerpc_opcode vle_opcodes[] = {
> >   {"se_bl",      BD8(58,0,1),    BD8_MASK,       PPCVLE,
> > 0,              {B8}},
> >   };
> > 
> > -const int vle_num_opcodes =
> > -  sizeof (vle_opcodes) / sizeof (vle_opcodes[0]);
> > -
> > +const int vle_num_opcodes = ARRAY_SIZE(vle_opcodes);
> > +
> >   /* The macro table.  This is only used by the assembler.  */
> > 
> >   /* The expressions of the form (-x ! 31) & (x | 31) have the
> > value 0
> > @@ -7276,5 +7273,4 @@ const struct powerpc_macro powerpc_macros[] =
> > {
> >   {"e_clrlslwi",4, PPCVLE, "e_rlwinm %0,%1,%3,(%2)-(%3),31-(%3)"},
> >   };
> > 
> > -const int powerpc_num_macros =
> > -  sizeof (powerpc_macros) / sizeof (powerpc_macros[0]);
> > +const int powerpc_num_macros = ARRAY_SIZE(powerpc_macros);
> > --
> > 2.49.1
> >