Implementation of variables in a stack-based Virtual Machine
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So i have written a basic virtual machine with a very small instruction set, capable of performing jumps, basic math operations and pushing and popping literal values onto the stack [I am currently storing instructions as an array of opcodes]. However, I now want to add instructions to handle variable assignment, and I was wondering how this was done.
- Do I use a separate stack for variables and literal values?
- How do I remember where these variables are on the stack if kept there?
- Do I need another data structure for keeping track of variable indexes on the stack?
Thank you
variables assembly stack virtual-machine
asked Nov 24 '18 at 20:13
kingstoncompscikingstoncompsci
111
add a comment |
2
So i have written a basic virtual machine with a very small instruction set, capable of performing jumps, basic math operations and pushing and popping literal values onto the stack [I am currently storing instructions as an array of opcodes]. However, I now want to add instructions to handle variable assignment, and I was wondering how this was done.
- Do I use a separate stack for variables and literal values?
- How do I remember where these variables are on the stack if kept there?
- Do I need another data structure for keeping track of variable indexes on the stack?
Thank you
variables assembly stack virtual-machine
asked Nov 24 '18 at 20:13
kingstoncompscikingstoncompsci
111
2
You can do however you want :) The JVM, for example, is a stack based VM where local vars are indexed (they are basically and array). If you save the local variables in the stack, make sure they are directly reachable without the need to pop everything pushed after their creation. Also, think of how much a variable have to live: do they live in the current frame/function (e.g. are they local vars)? do they live for the whole program duration (e.g. are they global vars)? The answer will tell you where to put them. Having another data structure seems fine to me.
– Margaret Bloom
Nov 24 '18 at 22:46
add a comment |
2
2
2
So i have written a basic virtual machine with a very small instruction set, capable of performing jumps, basic math operations and pushing and popping literal values onto the stack [I am currently storing instructions as an array of opcodes]. However, I now want to add instructions to handle variable assignment, and I was wondering how this was done.
- Do I use a separate stack for variables and literal values?
- How do I remember where these variables are on the stack if kept there?
- Do I need another data structure for keeping track of variable indexes on the stack?
Thank you
variables assembly stack virtual-machine
asked Nov 24 '18 at 20:13
kingstoncompscikingstoncompsci
111
So i have written a basic virtual machine with a very small instruction set, capable of performing jumps, basic math operations and pushing and popping literal values onto the stack [I am currently storing instructions as an array of opcodes]. However, I now want to add instructions to handle variable assignment, and I was wondering how this was done.
- Do I use a separate stack for variables and literal values?
- How do I remember where these variables are on the stack if kept there?
- Do I need another data structure for keeping track of variable indexes on the stack?
Thank you
variables assembly stack virtual-machine
variables assembly stack virtual-machine
asked Nov 24 '18 at 20:13
kingstoncompscikingstoncompsci
111
asked Nov 24 '18 at 20:13
kingstoncompscikingstoncompsci
111
asked Nov 24 '18 at 20:13
kingstoncompscikingstoncompsci
111
asked Nov 24 '18 at 20:13
kingstoncompscikingstoncompsci
111
asked Nov 24 '18 at 20:13
kingstoncompscikingstoncompsci
111
111
2
You can do however you want :) The JVM, for example, is a stack based VM where local vars are indexed (they are basically and array). If you save the local variables in the stack, make sure they are directly reachable without the need to pop everything pushed after their creation. Also, think of how much a variable have to live: do they live in the current frame/function (e.g. are they local vars)? do they live for the whole program duration (e.g. are they global vars)? The answer will tell you where to put them. Having another data structure seems fine to me.
– Margaret Bloom
Nov 24 '18 at 22:46
add a comment |
2
You can do however you want :) The JVM, for example, is a stack based VM where local vars are indexed (they are basically and array). If you save the local variables in the stack, make sure they are directly reachable without the need to pop everything pushed after their creation. Also, think of how much a variable have to live: do they live in the current frame/function (e.g. are they local vars)? do they live for the whole program duration (e.g. are they global vars)? The answer will tell you where to put them. Having another data structure seems fine to me.
– Margaret Bloom
Nov 24 '18 at 22:46
2
2
You can do however you want :) The JVM, for example, is a stack based VM where local vars are indexed (they are basically and array). If you save the local variables in the stack, make sure they are directly reachable without the need to pop everything pushed after their creation. Also, think of how much a variable have to live: do they live in the current frame/function (e.g. are they local vars)? do they live for the whole program duration (e.g. are they global vars)? The answer will tell you where to put them. Having another data structure seems fine to me.
– Margaret Bloom
Nov 24 '18 at 22:46
You can do however you want :) The JVM, for example, is a stack based VM where local vars are indexed (they are basically and array). If you save the local variables in the stack, make sure they are directly reachable without the need to pop everything pushed after their creation. Also, think of how much a variable have to live: do they live in the current frame/function (e.g. are they local vars)? do they live for the whole program duration (e.g. are they global vars)? The answer will tell you where to put them. Having another data structure seems fine to me.
– Margaret Bloom
Nov 24 '18 at 22:46
add a comment |
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You can do however you want :) The JVM, for example, is a stack based VM where local vars are indexed (they are basically and array). If you save the local variables in the stack, make sure they are directly reachable without the need to pop everything pushed after their creation. Also, think of how much a variable have to live: do they live in the current frame/function (e.g. are they local vars)? do they live for the whole program duration (e.g. are they global vars)? The answer will tell you where to put them. Having another data structure seems fine to me.
– Margaret Bloom
Nov 24 '18 at 22:46