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Re: CPSR changes to ARM binutils in the mainline...


> Philip Blundell wrote:
> > 
> > My preference (for both branch and trunk) would actually be to issue a warning
> > rather than an error for these sorts of instructions.  This is more consistent
> > with how the assembler handles other syntactically correct but invalid
> > instructions.
> 
> The instructions it refuses to compile are not syntactically correct AFAIK.  I
> think earlier assemblers were to lax.

No, to quote from the (old) ARM7 data sheet:

"No attempt shall be made to write an 8 bit immediate value into the whole 
PSR since such an operation cannot preserve the reserved bits."

So it is syntactically correct, but semantically invalid.

R.

[ Note that at the time of the ARM7 Data sheet, there were just two 
methods for writing the CPSR -- CPSR_flg and CPSR_all.  Later processors 
split the flags out further to give access to the 4 separate parts of the 
CPSR. ]


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