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try to turn off option for synthesis "Power up register with don't care value 'X'" <- it is default value.
but it is better do all signal assignments explicit, as pointed out by Kaz.
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I think the OP is about the difference between code1 and code2 cases.
code1) if you apply reset (in code) then assign value on clock edge you are asking for a register even though in this case it is waste because the signal is assigned '1' all the way through. So the compiler here is not that clever, wastes register and creates timing path.
code2) If you don't apply reset but just clock edge assignment then compiler gets clever and says you don't need register and so wires your signal to a constant and ignores clock edge assignment.
The conclusion is that if you have constants do not apply reset and so do not create registers and timing paths.
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