tied registers


I wonder if there is a simple way to define a 3-address instruction taking 4 operands, ie a

32regA = MAC (32regB, 16regC, 16regD) // widening mac instruction

Regs A and B should be handled like “src1 = dst”, but this does not work, I get odd results.

I wonder also how to generally select instructions when the widths of the input operands differ like this.