Dependence-Conscious Global Register Allocation

Register allocation and instruction scheduling are antagonistic optimizations: Whichever is applied rst, it will impede the other. To solve this problem, we propose dependence-conscious colouring, a register allocation method that takes the dependence graph used by the instruction schedu-ler into consideration. Dependence-conscious colouring consists of two parts: First, the interference graph is built by analysing the dependence graphs, resulting in fewer interference edges and less spilling than the conventional preordering approach. Second, during colouring the register selection keeps dependence paths short, ensuring good scheduling. Dependence-conscious colouring reduces the number of interference edges by 7%{24% and antidepen-dences by 46%{100%.