1)在采用retention单元的情况下,综合将加法结果视为常数而直接将其去掉,如下所示,摘自生产的log文件,请问什么情况下才会将综合结果视为常数而舍弃呢?
Beginning Mapping Optimizations (Ultra High effort)
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Information: Added key list 'DesignWare' to design 'ADD'. (DDB-72)
Information: Added key list 'DesignWare' to design 'MULT'. (DDB-72)
Information: The register 'I_ADD/add_out_reg[0]' is a constant and will be removed. (OPT-1206)
Information: The register 'I_ADD/add_out_reg[1]' is a constant and will be removed. (OPT-1206)