15 So the current compiler instead, in the frontend, generates a directed-acyclic-graph of instructions and basic blocks, which go through various additional passes to eventually schedule and do register assignment.
39     stages to schedule and do register assignment.
93 (after scheduling, etc, but before register assignment).
199 Before register assignment, to group the two components of the texture src together:
220 The frontend sets up the SSA ptrs from ``sam`` source register to the ``collect`` meta instruction, which in turn points to the instructions producing the ``coord.x`` and ``coord.y`` values.  And the grouping_ pass sets up the ``left`` and ``right`` neighbor pointers to the ``collect``\'s sources, used later by the `register assignment`_ pass to assign blocks of scalar registers.
263 Relative addressing of the const file (for example, a uniform array) is relatively simple.  We don't do register assignment of the const file, so all that is required is to schedule things properly.  I.e. the instruction that writes the address register must be scheduled first, and we cannot have two different address register values live at one time.
265 But relative addressing of gpr file (which can be as src or dst) has additional restrictions on register assignment (i.e. the array elements must be assigned to consecutive scalar registers).  And in the case of relative dst, subsequent instructions now depend on both the relative write, as well as the previous instruction which wrote that register, since we do not know at compile time which actual register was written.
345 After the frontend has generated the use-def graph of instructions, they are run through various passes which include scheduling_ and `register assignment`_.  Because inserting ``mov`` instructions after scheduling would also require inserting additional ``nop`` instructions (since it is too late to reschedule to try and fill the bubbles), the earlier stages try to ensure that (at least given an infinite supply of registers) that `register assignment`_ after scheduling_ cannot fail.
375 In the grouping pass, instructions which need to be grouped (for ``collect``\s, etc) have their ``left`` / ``right`` neighbor pointers setup.  In cases where there is a conflict (i.e. one instruction cannot have two unique left or right neighbors), an additional ``mov`` instruction is inserted.  This ensures that there is some possible valid `register assignment`_ at the later stages.
396 .. _`register assignment`:

Indexes created Sat Nov 29 09:09:30 GMT 2025