Mars assembly: Use atoms rather than variable names

[Matt Giuca]

In the Mars assembly code, all instructions refer to variable names. This means expressions with integer literals or constructor names need to be compiled into ld_intlit/ld_ctor instructions (to temporary variables), and then variable references. It would make assembly code much shorter and easier to read (by humans, anyway) if all instructions used *atoms* rather than variable names, where an atom is a variable name, constructor name, or int literal.

[Matt Giuca (mgiuca)]

Milestoning; it will be good to simplify the assembly representation, especially for string literals.

[Matt Giuca (mgiuca)]

Note: There is no longer a ld_ctor instruction. It has been replaced by ld_ctorsym (for constructor symbols/constants) and new_closure (for constructor functions). Clearly, constructor function names should no longer be atoms (as we always treat access to global objects with an explicit instruction now). But constructor symbols might be good candidates for atoms.

Therefore, let an atom refer to an integer or constructor symbol name (not a function), and replace the ld_intlit and ld_ctorsym instructions.

[Matt Giuca (mgiuca)]

This is now addressed in branch 'atom' r1265. It needs to be merged.

[Matt Giuca (mgiuca)]

Fixed in trunk r1262.