Code Path: src/runtime/slice.go makeslicecopy makeslicecopy is used for IR patterns like m = OMAKESLICE([]T, x); OCOPY(m, s), IR will rewrite this specific order of code path and replace it with OMAKESLICECOPY. If the elements has no pointer, SSA will generate code to do a mallocgc and memmove. Otherwise, the code will be expanded to makeslicecopy: Check the length of the slice to copy to. Do mallocgc Do memmove makeslice and `makeslice641 makeslice is used for make(slice, len, cap) statements, if cap is missing, by default it will be the same as len....

Static Definition and Initialization Code Path: src/runtime/iface.go In proc.go, itabsinit will init the itabTable with the current activeModules information. The itabsinit function will read the itablinks from each module and add them to the global hash table. During the runtime, the getitab function will also build more items dynamically and fill the hash table accordingly. itablinks was produced for each module during the linking stage, and contains an array of itab....

Compiling Code Path: src/cmd/compile/internal/ir/expr.go During the IR stage, each expression will get type info, it’s defined as miniExpr and can be assigned a types.Type value. Static Typing: types2 Code Path: src/cmd/compile/internal/types2 types and `types2 Conversion Code Path: src/cmd/compile/internal/noder/types.go Currently, both packages are in use, but much logic is being migrated to types2 package. types2 package was introduced as part of go generic features and has a better code structure than the old types package....

Ref Garbage Collector Code Path: src/runtime/mgc.go gcinit gcinit runs after almost everything set up in schedinit. Set sweepDrainedMask Initialize gcController with GOGC (for GC percentage control) and GOMEMLIMIT (for memory limits). Initialize work semaphores. gcenable gcenable happens in the main goroutine, right after runtime_inittask. Start bgsweep Start bgscavenge GC GC runs a full garbage collection. Each run will finish the current GC cycle: sweep termination, mark, mark termination, and sweep....

Stack Management Code Path: src/runtime/stack.go Stack pools are initialized before mheap_, because we don’t allocate any memory during this stage. Right after the stack pools initialized, the mheap_ will be initialized so later stack allocation is possible. stackpool stackpool is managed by the “order” (based on the ratio of stack size and _FixedStack) of the stack, each order of stack has its own stack pool. In stackinit, the stack pool will be initialized right after moduledataverify....

Code Path: src/runtime/proc.go Start-Up Process of a Go program. Take src/runtime/asm_arm.s as an example: Take the address of g0 and m0. Set up m.g0 and g.m. Create istack. Do runtime check. Save argc and argv. Call runtime.osinit. Call runtime.schedinit. Call runtime.newproc for the main function. call runtime.mstart to start the M. runtime.osinit Take src/runtime/os_linux.go as an example: Get the number of processors. This is done by making a syscall SYS_sched_getaffinity....

Preface Code path: src/runtime/proc.go Data structures are defined under src/runtime/runtime2.go. Concepts Copied from source code: // G - goroutine. // M - worker thread, or machine. // P - processor, a resource that is required to execute Go code. // M must have an associated P to execute Go code, however it can be // blocked or in a syscall w/o an associated P. main Set up stack size. Fork a new m and run the sysmon function, except the wasm platform....

Path: src/runtime/chan.go Compilation When you make a chan with make function, the compiler will expand the expression to the makechan implementation. The actual expansion happens at cmd/compile/internal/walk/expr.go. The runtime will determine whether to use makechan or makechan64. Type Definitions type _type _type is used as the internal representation of a go type. The same structure is defined multiple times across the go runtime. _type stores the following fields: type chantype makechan only uses chantype....

ssagen.Compile Build SSA for the ir.Func (buildssa) Check ssaDump and set the dump flag. Initialize ssagen.state. Push the line number or the parent’s line number (if it’s missing) to the stack. Set up ssagen.state flags from ir.Func information. Set up an empty ssagen.ssafn with ir.Func and ABI information. Allocate the starting block for the current ssa.Func. Check open-coded defers. <- What’s this? Do ABIAnalyze, get the abi.ABIParamResultInfo of function in/out parameters....

irgen.generate Check each file’s pragma list and DeclList. Generate ir.Decl for type declarations. Generate ir.Decl for other declarations. Process later functions, this step is for the same purpose as type check. Type-check CallExpr again. Check missing function bodies. Build generic instantiations. It scans calls and generated needed methods. Remove all generic Decl’s. After irgen.generate, g.target.Decls will be the final Decl’s to generate. enqueueFunc and compileFunctions This step is the compile step of cmd/compile, it happens after type checking and IR generation....