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FRIGG: A New Approach to Combining Register Assignment and Instruction Scheduling
| Content Provider | Semantic Scholar |
|---|---|
| Author | Brasier, Thomas S. |
| Copyright Year | 1994 |
| Abstract | In Instruction Level Parallel (ILP) compilers, the phases of register assignment and instruction scheduling can be antagonistic. When register assignment is executed before instruction scheduling, false dependences can be added due to register reuse. These false dependences often inhibit the scheduler’s ability to generate faster code. When instruction scheduling is executed before register assignment, schedules may be generated that cannot keep all values in registers, and thus, slow memory accesses will be required for some values. This work investigates the relationship between graph-coloring register assignment and instruction scheduling and evaluates a new register assignment framework called Full Register Interference Graph Generation (FRIGG). The basic FRIGG technique is removing anti-dependences from the early (before instruction scheduling) register assignment interference graph by adding edges from the interference graph generated by doing late (after instruction scheduling) register assignment. In doing this, FRIGG tries to gain the benefits of late register assignment when it is advantageous. Otherwise, FRIGG attempts to create a compromise between early and late register assignment by using the information gained from the initial pass of late register assignment. In doing this, we attempt to maximize code re-ordering while reducing spill code. A simple version of this algorithm has been implemented in a retargetable C Compiler and, through testing, it has been found that the FRIGG framework makes significant improvements by reducing execution times of several benchmark programs when compared to early register assignment. When there are not enough registers for late register assignment without spilling, the proposed algorithm will converge on a valid solution, and will often improve on the results of doing late register assignment with spilling. |
| File Format | PDF HTM / HTML |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
