Processor Description Languages

10.4 Sets and Regular Expressions as Language Constructs 265

be an assembler-recognized register. For the microarchitecture references, we can

define the physical registers as generic 32-bit registers using a built-in ar tifact:

register file

gpr [8, 32] # 8 registers, 32 bits each

"%reg0" 0, "%reg1" 1, "%reg2" 2, "%reg3" 3,

"%reg4" 4, "%reg5" 5, "%reg6" 6, "%reg7" 7;

We can now use a union to define the symbolic registers and the parts of the physical

register used. In the notation

[start_bit:length] bits are numbered from high bit down

to zero.

union

"%eax" %reg0[31:32], "%ecx" %reg1[31:32], .... # 32 bit registers

"%ax" %reg0[15:16], "%cx" %reg1[15:16], ...