Summary - Compiler
- Go course
- Expert
- Lesson 18/34
- 4 min
Combine SSA, escape and inline to write a compilation analysis.
Compiler summary
Source → type checking → IR (escape analysis + inlining) → SSA (constant folding, dead code, BCE) → machine code → linking. Your inspection tools: -gcflags=-m (escape and inlining), -gcflags=-S (assembly), GOSSAFUNC (SSA passes), -d=ssa/check_bce (bounds checks). With directives (//go:build, //go:embed, //go:noinline) you instruct the compiler.
Readability comes first
Compiler knowledge should be applied at the hot spots a profile shows. Adding BCE hints and noinline everywhere hurts readability and may become unnecessary in later Go versions, as the compiler gets smarter with each release. The rule: measure, find the hot spot, confirm the change with a benchmark.
Practice A buffer that stays on the stack
Write an allocation-light function using a fixed-size array: inside hex(b byte) string fill var buf [2]byte and return string(buf[:]). Print hex(255) (output ff).
Starter code
package main
import "fmt"
func main() {
// buraya yaz
}Sample solution
package main
import "fmt"
const rakam = "0123456789abcdef"
func hex(b byte) string {
var buf [2]byte
buf[0] = rakam[b>>4]
buf[1] = rakam[b&0x0f]
return string(buf[:])
}
func main() {
fmt.Println(hex(255))
}Expected output
ff
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 If a hot function allocates on the heap every call, which output do you check first?
- go mod tidy
- gofmt -d
- go build -gcflags=-m Correct answer
- go vet
Explanation: The -m output tells which variable escapes to the heap and why, with line numbers.
2 SSA visualization
____=topla go build .GOSSAFUNC=topla go build .Explanation: GOSSAFUNC draws all SSA passes of the given function into ssa.html.
3 Group summary
| Term | Meaning |
|---|---|
Escape analysis |
Stack or heap? |
Inlining |
Replace call with body |
SSA |
Optimization form |
//go:build |
Conditional compilation |