Based on the code you pasted here (It's VLIW5 code), I suggest you read this manual -> http://developer.amd.com/tools/hc/AMDAPPSDK/assets/AMD_Evergreen-Family_Instruction_Set_Architecture.pdf
Double digit numbers (00,01,...)are the clause indexes. Clauses are used to specify program flow and encapsulate alu instructions.
Numbers indented inside clauses are instruction indexes.
x,y,z,w,t selects the instruction slot inside a VLIW instruction.
On the AMD's VLIW5 architecture the x,y,z,w slots are for simple instructions, and the t slot is used for rare ones (for example MULLO_INT can go only to the t slot).
Later there came VLIW4 with the HD6970: There are four all-purpose slots: x,y,z,w.
And now there is GCN architecture (HD7970) which is completely different from VLIW.
Thanks! exactly what I was looking for, also thank you for the summary, it is very much appreciated.