| Evan Cheng | 3578dd6 | 2007-03-20 22:22:38 +0000 | [diff] [blame^] | 1 | Common register allocation / spilling problem: |
| 2 | |||||
| 3 | mul lr, r4, lr | ||||
| 4 | str lr, [sp, #+52] | ||||
| 5 | ldr lr, [r1, #+32] | ||||
| 6 | sxth r3, r3 | ||||
| 7 | ldr r4, [sp, #+52] | ||||
| 8 | mla r4, r3, lr, r4 | ||||
| 9 | |||||
| 10 | can be: | ||||
| 11 | |||||
| 12 | mul lr, r4, lr | ||||
| 13 | mov r4, lr | ||||
| 14 | str lr, [sp, #+52] | ||||
| 15 | ldr lr, [r1, #+32] | ||||
| 16 | sxth r3, r3 | ||||
| 17 | mla r4, r3, lr, r4 | ||||
| 18 | |||||
| 19 | and then "merge" mul and mov: | ||||
| 20 | |||||
| 21 | mul r4, r4, lr | ||||
| 22 | str lr, [sp, #+52] | ||||
| 23 | ldr lr, [r1, #+32] | ||||
| 24 | sxth r3, r3 | ||||
| 25 | mla r4, r3, lr, r4 | ||||
| 26 | |||||
| 27 | It also increase the likelyhood the store may become dead. | ||||