The following code comes from GSA, I can't understand the instruction "x: MUL_e R0.x, R0.x, R1.x ", I think the second R0.x here is a source register, but it has no initial value, why?
; -------- Disassembly --------------------
00 ALU_PUSH_BEFORE: ADDR(32) CNT(1) KCACHE0(CB0:0-15)
0 x: PREDNE_INT ____, KC0[0].x, 0.0f UPDATE_EXEC_MASK UPDATE_PRED
01 JUMP POP_CNT(1) ADDR(4) VALID_PIX
02 TEX: ADDR(48) CNT(1) VALID_PIX
1 SAMPLE R1, R1.xy0x, t0, s0
03 ALU_POP_AFTER: ADDR(33) CNT(4)
2 x: MUL_e R0.x, R0.x, R1.x
y: MUL_e R0.y, R0.y, R1.y
z: MUL_e R0.z, R0.z, R1.z
w: MUL_e R0.w, R0.w, R1.w
04 EXP_DONE: PIX0, R0
END_OF_PROGRAM
