9.43.3.5 Size Translations

Often it is desirable to write code in an operand size agnostic manner. as provides support for this via operand size opcode translations. Translations are supported for loads, stores, shifts, compare-and-swap atomics, and the ‘clr’ synthetic instruction.

If generating 32-bit code, as will generate the 32-bit opcode. Whereas if 64-bit code is being generated, the 64-bit opcode will be emitted. For example ldn will be transformed into ld for 32-bit code and ldx for 64-bit code.

Here is an example meant to demonstrate all the supported opcode translations:

     ldn   [%o0], %o1
     ldna  [%o0] %asi, %o2
     stn   %o1, [%o0]
     stna  %o2, [%o0] %asi
     slln  %o3, 3, %o3
     srln  %o4, 8, %o4
     sran  %o5, 12, %o5
     casn  [%o0], %o1, %o2
     casna [%o0] %asi, %o1, %o2
     clrn  %g1

In 32-bit mode as will emit:

     ld   [%o0], %o1
     lda  [%o0] %asi, %o2
     st   %o1, [%o0]
     sta  %o2, [%o0] %asi
     sll  %o3, 3, %o3
     srl  %o4, 8, %o4
     sra  %o5, 12, %o5
     cas  [%o0], %o1, %o2
     casa [%o0] %asi, %o1, %o2
     clr  %g1

And in 64-bit mode as will emit:

     ldx   [%o0], %o1
     ldxa  [%o0] %asi, %o2
     stx   %o1, [%o0]
     stxa  %o2, [%o0] %asi
     sllx  %o3, 3, %o3
     srlx  %o4, 8, %o4
     srax  %o5, 12, %o5
     casx  [%o0], %o1, %o2
     casxa [%o0] %asi, %o1, %o2
     clrx  %g1

Finally, the ‘.nword’ translating directive is supported as well. It is documented in the section on Sparc machine directives.