Questions tagged [optimization]
Use this tag for questions about efficient compilation or execution of a programming language, including in a virtual machine, or language features that facilitate more efficient code generation or execution for interpreters
33
questions
2
votes
1
answer
146
views
How to assign unique names to variables within a function?
I want to promote all variables within the function to the top level of the function, make it more cache-friendly and reduce size bloat caused by alignment fill.
In other words, it will roughly ...
- 2,552
-2
votes
1
answer
126
views
Low effort, high impact optimizations? [closed]
The Pareto principle tells us that 20% of our efforts will bring us 80% of the results. The same should be true of optimizations.
Are there optimization techniques out there that:
Are simple and easy ...
- 125
1
vote
0
answers
185
views
Pros and cons of treating endless loops as "anything can happen" UB, versus allowing limited reordering
Many programming languages, including C89, specify that the behavior of a program in terms of sequentially executed steps, whose behavior is in turn defined in terms of the program's state when the ...
- 1,560
4
votes
0
answers
117
views
Determining the most optimized date type for the platform with type inference
For my programming language, I have built an engine that goes after the parser and before the compiler. This engine analyzes, validates, and simplifies the AST.
During the analasys, it determines as ...
- 171
-1
votes
0
answers
64
views
In C, which approach is preferable: modifying a pointer's address within a void function or assigning the mutated pointer through its return value? [closed]
I have two conflicting theories regarding the optimal approach when passing the address of a pointer, particularly within a function like insert_front for a linked list. I seek insights based on ...
5
votes
1
answer
183
views
Optimization algorithm using conditional invariants
I am looking for an optimization algorithm that would make use of invariants in regions of code. For example
if (n == 0) f(n);
should be changed to
...
- 628
10
votes
1
answer
431
views
Towards a better default listlike datastructure for functional languages
In most functional languages I know of, linked lists are the default datastructure of choice for many operations. The benefits are clear - they're clearly encoded with ADTs, and can be utilised easily ...
- 1,582
6
votes
2
answers
183
views
How to ensure coherent choices of representatives in an e-graph?
E-graphs are a neat intermediate representation for program transformations and optimisations, which group program terms into equivalence classes (e-classes). An optimising compiler can then select ...
- 16.3k
8
votes
1
answer
502
views
What are the tradeoffs between using sea of nodes, CFG of basic blocks, and egraphs for compiler optimizations?
I've heard of "sea of nodes" intermediate representations mostly in the context of just-in-time compilation (JVM, V8, Graal) whereas intermediate representations such as LLVM IR are used in ...
- 91
34
votes
6
answers
4k
views
How to ensure that an optimising compiler will terminate?
An optimising compiler typically applies some set of rewrites to some intermediate representation of the program, replacing terms with other terms which are supposed to be equivalent but more ...
- 16.3k
4
votes
1
answer
217
views
Can analysis of periodic loop behaviour be generalised to unstructured control flow?
The basic form of a loop is as follows:
loopvars := init
body:
loopvars := f(loopvars)
done := term(loopvars)
br done, end, body
end:
Suppose we've recognised ...
- 717
5
votes
2
answers
235
views
Why would external iteration require lots of code inlining relative to internal iteration?
In Graydon Hoare's blogpost The Rust I Wanted Had No Future, they state that:
Iteration used to be by stack / non-escaping coroutines, which we also called "interior" iteration, as opposed ...
- 649
6
votes
2
answers
658
views
Empirically, what are the implementation-complexity and performance implications of "unboxed" primitives?
I'm designing a Python-like language: bytecode-compiled, brace-free syntax, reference semantics for variables. Among many differences from Python, I want to support a limited form of static typing. I ...
- 1,155
24
votes
4
answers
3k
views
Pros and cons of "anything-can-happen" UB versus allowing particular deviations from sequential program execution
Some language specifications invite compilers to make certain assumptions, and behave in completely arbitrary fashion if such functions are violated, even if the code in question would have ...
- 1,560
6
votes
2
answers
314
views
How to optimize non-tail recursion?
Tail recursion, where a function calls itself as the last step, is straightforward to optimize as to prevent unbounded stack growth: tail call optimization applies.
However, this doesn't apply to ...
- 8,553
4
votes
0
answers
178
views
Why has there been little recent work on GPU compiler phase optimization?
While GPU compiler phase optimization has been shown to improve performance significantly (e.g. https://link.springer.com/chapter/10.1007/978-3-319-75178-8_35), there has been very little follow-up ...
- 141
8
votes
3
answers
542
views
Tail-recursive detection and conversion
Motivation
I have implemented the tail recursion optimization for my language, where a return statement calls itself by goto ...
- 2,552
-4
votes
1
answer
211
views
What are the disadvantages of including foreach loops? [duplicate]
Yes, FOR loops. Those great things. There are good for shortening code. But there may be downsides I'm not aware of. I'm referring to Python style FOR loops. So, what are the disadvantages of ...
5
votes
1
answer
159
views
Automatic copy to move promotion
I'm designing a language that has move semantics similar to C++. To make it more efficient and to prevent the need for explicit moves I want to automatically promote copies to moves if the compiler ...
- 628
16
votes
7
answers
2k
views
What are the pitfalls of using an existing IR/compiler infrastructure like LLVM?
Using something like LLVM when designing a compiler has a lot of advantages, since tons of work can be saved by using an existing optimizer and code generation for a variety of platforms. Even large, ...
- 4,070
14
votes
0
answers
359
views
What is the relationship between STG and RVSDG?
GHC is an optimizing Haskell compiler. Since Haskell is lazy and mutation is rare, control flow and data flow are often very closely aligned. Therefore, it is often most useful to think about ...
- 7,779
4
votes
3
answers
548
views
What are some common ways to optimise an interpreter?
Optimization is getting things to work faster with less resources.
What are some ways to optimize an interpreter?
2
votes
3
answers
166
views
What are the downsides, if any, of using implicit function purity in an impure language?
An idea I had for one of my languages recently was this: function purity makes it easier to do certain optimizations. However, the language I'm designing is an impure imperative language that has an ...
- 2,594
2
votes
2
answers
157
views
What are the disadvantages of automatically inlining all functions?
Function inlining is when the function called is directly substituted in the calling code. This avoids the overhead of setting up the call stack, managing any relevant pointers that need to be tracked ...
- 1,553
4
votes
2
answers
139
views
How to estimate which parts of a program will be slow?
Many modern compilers are sophisticated enough to determine that some functions or expressions can be computed lazily, memoised, or parallelised. For example, pure functions can be computed at any ...
- 16.3k
8
votes
1
answer
162
views
Syntax options for providing branch prediction information
Branch prediction information can affect performance. Languages to provide programmers with ways to provide branch prediction hints to improve performance of code. One option is C++ ...
- 7,245
5
votes
2
answers
713
views
Why was C implemented with a register preservation convention that seems to be far less efficient than its predecessor's?
In original implementations of the B language, the caller was responsible for saving and restoring any registers it cares about before calling a function.
But in the C language, the called function is ...
- 1,157
6
votes
2
answers
272
views
Are there any disadvangates to requiring sincos() type functions?
sincos() is just a way to compute sin() and cos() at once, possibly at improved performance ...
- 7,245
7
votes
2
answers
218
views
How to implement dynamic scoping?
How to implement dynamic scoping?
Dynamic scoping is useful for forms of dependency injection, error handling and alternatives to thread local storage.
Some examples of dynamic scoping include React's ...
5
votes
1
answer
132
views
Which functions should a compiler cache outputs for?
Because a bare function object might not have constant time complexity, and because the function object might be called with the same argument repeatedly, I thought it might be good to cache its ...
- 495
4
votes
1
answer
189
views
Implementing a number to string semantics efficiently in a C-style language?
In C our options for converting numbers to strings and adding them to a string are limited to:
Write your own function.
sprintf() to a buffer.
Either way, one ...
- 7,245
12
votes
2
answers
325
views
Which calling convention should my compiler use?
The LLVM-IR Reference Manual's section on Calling Conventions lists as many as 15 supported calling conventions. These vary in ways including whether they support tail call optimization, how many and ...
- 4,070
13
votes
7
answers
710
views
How can a programming language support vectorization portably?
C and C++ have no vector types or operations but many compilers offer their own non-portable extensions such as __attribute__((__ext_vector_type__())). The issue is ...
- 7,245