Drawing A Dependency Graph; Dependency Graph Of Fixed-Point Dot Product With Ldw - Texas Instruments TMS320C6000 Programmer's Manual

Using Word Access for Short Data and Doubleword Access for Floating-Point Data
6.4.3

Drawing a Dependency Graph

Figure 6–5. Dependency Graph of Fixed-Point Dot Product With LDW
6-22
The dependency graph in Figure 6–5 for the fixed-point dot product shows that
the LDW instructions are parents of the MPY instructions and the MPY instruc-
tions are parents of the ADD instructions. To split the graph between the A and
B register files, place an equal number of LDWs, MPYs, and ADDs on each
side. To keep both sides even, place the remaining two instructions, B and
SUB, on opposite sides.
1
1
Similarly, the dependency graph in Figure 6–6 for the floating-point dot prod-
uct shows that the LDDW instructions are parents of the MPYSP instructions
and the MPYSP instructions are parents of the ADDSP instructions. To split
the graph between the A and B register files, place an equal number of
A side
LDW
ai & ai+1
5
5
5
MPY
pi
2
ADD
1
sum0
SUB
cntr
B
1
LOOP
B side
LDW
bi & bi+1
5
MPYH
pi+1
2
ADD
sum1