Assignments can only exist at the top level instruction stream; the
residual value is handled by assigning the value to a temporary and
returning an ir_dereference_variable of that temporary.
This is quite a large patch because breaking it into smaller pieces
would result in the tree being intermitently broken. The big changes
are:
* Add the ir_var_temporary variable mode
* Change the ir_variable constructor to take the mode as a
parameter and correctly specify the mode for all ir_varables.
* Change the linker to not cross validate ir_var_temporary
variables.
* Change the linker to pull all ir_var_temporary variables from
global scope into 'main'.
This currently involves an ugly hack so that every link doesn't result
in all the built-in functions showing up as multiply defined. As soon
as the built-in functions are stored in a separate compilation unit,
ir_function_signature::is_built_in can be removed.
_mesa_glsl_parse_state should be the parent for all temporary allocation
done while compiling a shader. glsl_shader should only be used as the
parent for the shader's final IR---the _result_ of compilation.
Since many IR instructions may be added or discarded during optimization
passes, IR should not ever be allocated to glsl_shader directly.
Done via sed -i s/talloc_parent(state)/state/g and s/talloc_parent(st)/st/g.
This also removes a ton of talloc_parent calls, which may help performance.
