Scheme to implement translation

. E has attributes truelist and falselist

. L and S have a list of unfilled quadruples to be filled by backpatching

. S while E do S ₁ requires labels S.begin and E.true

- markers M₁ and M₂ record these labels S while M ₁E do M ₂ S₁

- when while. .. is reduced to S backpatch S ₁ .nextlist to make target of all the statements to

M ₁ .quad

- E.truelist is backpatched to go to the beginning of S ₁ (M ₂ .quad)

E has attributes truelist and falselist. L and S have a list of unfilled quadruples to be filled by backpatching.

For example consider S while E do S₁

M ₁and M ₂are used to record the quad numbers of S.begin and E.true respectively. B ackpatching is used to ensure that all targets on S ₁ . nextlist are M ₁ .quad. E.truelist is back-patched to go to the beginning of S ₁ by making jumps on E.truelist targeted towards M ₂ .quad. A n explicit jump to the beginning of the code for E is appended after the code for S₁ to prevent control from "falling out the bottom".