Code generation issues in compiler design code#
Start by browsing code of simple examples. JavaScript makes a great target language? Why? It’s got first-class functions and async support, and that Node.js thing runs on that awesome V8. Should we stick in line number information so a debugger can take over if our program is stopped intentionally (or crashes)?.Mov x_2, rax Redundant if x not used again Should we generate awesome code on the fly? Or let a separate optimizing pass clean up after our generator? Or not optimize at all? For example, naive code generation can lead to not so great code:.Absolute machine language: you’ve resolved all the memory locations in other words you spent a lot of time doing what assemblers and linkers would do for you already.Relocatable machine language: you’ve done a lot of assembly that the assembler would have done for you (resolving symbols), but at least you will let the linker do the rest.Is it a RISC or CISC processor or some kind of novel architecture like a dataflow processor or somthing with hundreds of cores? What are the relative instruction speeds? How are its addressing modes? Does it have out-of-order instruction? Any cool idioms? Assembly language: Because it’s so fulfilling to learn about machine architecture, especially pipelines, caches, and of course, registers! You need to know your machine.You’ll get a great feeling of accomplishment. Learning about a VM and its instruction set is a great experience. Targeting a virtual machine is a ton of fun. Executable virtual machine code, such as for the JVM or BEAM.An intermediate representation like LLVM, that has backends for dozens of architectures.But then you can let the C compiler take over to do the rest. If the target high-level language has a good compiler already, this is a great strategy. There is no one target of a code generator. There is no one way to do code generation. ) but the example above should get you started.Exercise: The last two goals are seemingly in conflict. Things might get trickier if the condition contains multiple conditions (and, or. if condition is false jump sizeof(codeblockA+1) instructions further.Then the code for the if-then-else-endif statement can be written like this (pseudo code): Suppose that our compiler has generated the code for someexpressionsA, called codeblockA (same for B). then the code for the if-then-else-endif statement.The bottom-up compilation means that the code will be generated like this: Suppose you have this piece of code: if (condition) then If your compiler generates the code bottom-up (from the most inside statement to the most outside statement), and your underlying machine (physical or virtual) supports relative jumps, then you can simply generate the relative jumps when generating the code.
Code generation issues in compiler design Patch#
If your compiler generates the code sequentially (from the first line of the code to the last one), then the only thing you can do is to remember the places where you want to jump to (store them in a table), and patch the code after everything has been generated. It depends on how and when your compiler will generate code. I'm a beginner and thus any suggestions/thoughts would be greatly appreciated. But what's the approach to point to a different tree from somewhere in the middle of a program? What is the approach I should be using to build symbol tables for function calls? In other words for different lexical levels? I know this should somehow involve having multiple trees. I have been able to build and use a symbol table for a single function. So now, my question is, how do I generate the addresses for "go to" statements?Ģ) This question is about semantic analysis: If (Rx) // Rx is the register where the expression is evaluated and stored Now, in my target code, it has to be a 3-address code with go to statements, so it should look something like: I am in the middle of developing a compiler for a C like language and am having some difficulties in the semantic analysis and code generation phases.ġ) For an if statement, the following is the syntax: if (expression) then
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