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Use bseti when profitable. Many cases of poor constant synthesis are failure to use bseti.Use "uw" variants of shifts/arithmetic instructions when the constant has bit 0x80000000 set.Use shNadd for constants evenly divisible by 9, 5 or 3.Use blcri in conjunction with lui or addi to clear a small number of bits, particularly in the high 33 bits of a 64bit word- Adjust constant so low 13 bits are 0x1800, recursively re-synthesize and restore low bits with trailing addi.
- Explore if we are using NOT effectively. ie, synthesize the inverted constant, then NOT the result to get the desired constantSynthesize C' from C using bit inversion. Synthesize C', then invert the result. If that's better than synthesizing C directly, then use the inversion sequence.
- Use pack for repeating constants
- Use pack as synthesis of last resort
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Updates
- Synthesizing the inverted constant, then inverting the result submitted upstream
- bclr method for generating constants integrated upstream
- Adjustment of low 13 bits to make easier to synthesize constant development submitted upstream
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