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a Further improvements of the G-machine code This section discusses two kinds of improvements of the G-machine code, which is not embodied in the compiler given in the previous section: improved tail recursive behaviour and exploiting the knowledge that a variable has been previously evaluated. Both kinds of improvements are included in our compiler implementation.

Figure 7 a Further improvements of the G-machine code This section discusses two kinds of improvements of the G-machine code, which is not embodied in the compiler given in the previous section: improved tail recursive behaviour and exploiting the knowledge that a variable has been previously evaluated. Both kinds of improvements are included in our compiler implementation.

Related Figures (8)

In our graph reduction scheme each function defini- tion is compiled into a sequence of G-machine instructions. Each graph rewrite, according to a function definition, is carried out by executing the code for that function. We here illustrate execution of the G-machine with the reduction step (e)-(a) from figure 1. The G-machine state transi- tions are shown in figure 2.
In our graph reduction scheme each function defini- tion is compiled into a sequence of G-machine instructions. Each graph rewrite, according to a function definition, is carried out by executing the code for that function. We here illustrate execution of the G-machine with the reduction step (e)-(a) from figure 1. The G-machine state transi- tions are shown in figure 2.
The execution of this code sequence is shown ir figure 3. The addition is done on a separate stack for basic values, called V, with instructions MKIN‘ and GET for transfering values to and from the graph. PUSHBASIC pushes a basic value constant az the V stack.
The execution of this code sequence is shown ir figure 3. The addition is done on a separate stack for basic values, called V, with instructions MKIN‘ and GET for transfering values to and from the graph. PUSHBASIC pushes a basic value constant az the V stack.
The initial configuration of the machine for a given program is shown in figure 4. The machine starts with an empty output, a code sequence c, for se ; ie) evaluating and printing the start expression e,, an empty pointer stack and an empty basic value stack, an empty graph, an environment Ey containing the compiled code for the functions together with their arity, and an empty dump-
The initial configuration of the machine for a given program is shown in figure 4. The machine starts with an empty output, a code sequence c, for se ; ie) evaluating and printing the start expression e,, an empty pointer stack and an empty basic value stack, an empty graph, an environment Ey containing the compiled code for the functions together with their arity, and an empty dump-
of the stack new points to the m curried arguments of the function, and below them there is a pointer to the apply node which is to be updated with the value of the application. The reason for remaking the stack in this manner is firstly to make the function arguments easily accessible, and secondly to access function arguments and local variables introduced by let and letrec expressions uniformly. Figure 5. Rearrangement of the stack after unwind.
of the stack new points to the m curried arguments of the function, and below them there is a pointer to the apply node which is to be updated with the value of the application. The reason for remaking the stack in this manner is firstly to make the function arguments easily accessible, and secondly to access function arguments and local variables introduced by let and letrec expressions uniformly. Figure 5. Rearrangement of the stack after unwind.
The new scheme S emits a code sequence to rearrange the stack in the manner shown in figure 8, and then Figure 8. Rearranging the stack for tail calls. a direct jump is performed to the first instruction of f, thus turning tail recursion into loops in the G-machine code. Using this method on our little example above, assuming f only takes one argument, we would get
The new scheme S emits a code sequence to rearrange the stack in the manner shown in figure 8, and then Figure 8. Rearranging the stack for tail calls. a direct jump is performed to the first instruction of f, thus turning tail recursion into loops in the G-machine code. Using this method on our little example above, assuming f only takes one argument, we would get
Related topics:
Computer ScienceFunctional ProgrammingLazy EvaluationGraph ReductionAbstract machine
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