How Does the Go Compiler Decide When to Inline Functions?

Compiler Logic for Function Inlining in Go

In Go, unlike C , the compiler autonomously determines which functions are appropriate for inlining. Although there is a debugging option to observe potential inlining, there is limited documentation regarding the exact criteria used by the Go compiler.

Inlining Optimization

Considering the need to execute a loop over a data set repeatedly, let's examine the code below:

func Encrypt(password []byte) ([]byte, error) {
    return bcrypt.GenerateFromPassword(password, 13)
}

for id, data := range someDataSet {
    newPassword, _ := Encrypt([]byte("generatedSomething"))
    data["password"] = newPassword
    someSaveCall(id, data)
}

Considerations for Inlining

To potentially qualify the Encrypt function for inlining by the compiler, consider the following:

• Function Simplicity: Small and linear functions without complex control flow or recursion are more likely to be inlined.
• Call Frequency: Frequently called functions, especially within loops, are good candidates for inlining.
• Size: Larger functions are less likely to be inlined due to code size concerns.

Compiler Logic

The Go compiler performs two passes for inlining:

1. CanInline: This pass identifies suitable functions for inlining and preserves their bodies.
2. InlineCalls: This pass expands calls to inlinable functions within function bodies.

The aggressiveness of inlining can be adjusted using the 'l' debug flag.

Recommendation

Unless performance becomes an issue, relying on the compiler's default inlining behavior is generally recommended. However, if significant performance gains are necessary, consider manually inlining small, frequently called functions to minimize overhead.

The above is the detailed content of How Does the Go Compiler Decide When to Inline Functions?. For more information, please follow other related articles on the PHP Chinese website!