go/src/cmd/compile/internal/devirtualize/pgo.go

type CallStat …

// ProfileGuided performs call devirtualization of indirect calls based on
// profile information.
//
// Specifically, it performs conditional devirtualization of interface calls or
// function value calls for the hottest callee.
//
// That is, for interface calls it performs a transformation like:
//
//	type Iface interface {
//		Foo()
//	}
//
//	type Concrete struct{}
//
//	func (Concrete) Foo() {}
//
//	func foo(i Iface) {
//		i.Foo()
//	}
//
// to:
//
//	func foo(i Iface) {
//		if c, ok := i.(Concrete); ok {
//			c.Foo()
//		} else {
//			i.Foo()
//		}
//	}
//
// For function value calls it performs a transformation like:
//
//	func Concrete() {}
//
//	func foo(fn func()) {
//		fn()
//	}
//
// to:
//
//	func foo(fn func()) {
//		if internal/abi.FuncPCABIInternal(fn) == internal/abi.FuncPCABIInternal(Concrete) {
//			Concrete()
//		} else {
//			fn()
//		}
//	}
//
// The primary benefit of this transformation is enabling inlining of the
// direct call.
func ProfileGuided(fn *ir.Func, p *pgoir.Profile) { … }

// Devirtualize interface call if possible and eligible. Returns the new
// ir.Node if call was devirtualized, and if so also the callee and weight of
// the devirtualized edge.
func maybeDevirtualizeInterfaceCall(p *pgoir.Profile, fn *ir.Func, call *ir.CallExpr) (ir.Node, *ir.Func, int64) { … }

// Devirtualize an indirect function call if possible and eligible. Returns the new
// ir.Node if call was devirtualized, and if so also the callee and weight of
// the devirtualized edge.
func maybeDevirtualizeFunctionCall(p *pgoir.Profile, fn *ir.Func, call *ir.CallExpr) (ir.Node, *ir.Func, int64) { … }

// shouldPGODevirt checks if we should perform PGO devirtualization to the
// target function.
//
// PGO devirtualization is most valuable when the callee is inlined, so if it
// won't inline we can skip devirtualizing.
func shouldPGODevirt(fn *ir.Func) bool { … }

// constructCallStat builds an initial CallStat describing this call, for
// logging. If the call is devirtualized, the devirtualization fields should be
// updated.
func constructCallStat(p *pgoir.Profile, fn *ir.Func, name string, call *ir.CallExpr) *CallStat { … }

// copyInputs copies the inputs to a call: the receiver (for interface calls)
// or function value (for function value calls) and the arguments. These
// expressions are evaluated once and assigned to temporaries.
//
// The assignment statement is added to init and the copied receiver/fn
// expression and copied arguments expressions are returned.
func copyInputs(curfn *ir.Func, pos src.XPos, recvOrFn ir.Node, args []ir.Node, init *ir.Nodes) (ir.Node, []ir.Node) { … }

// retTemps returns a slice of temporaries to be used for storing result values from call.
func retTemps(curfn *ir.Func, pos src.XPos, call *ir.CallExpr) []ir.Node { … }

// condCall returns an ir.InlinedCallExpr that performs a call to thenCall if
// cond is true and elseCall if cond is false. The return variables of the
// InlinedCallExpr evaluate to the return values from the call.
func condCall(curfn *ir.Func, pos src.XPos, cond ir.Node, thenCall, elseCall *ir.CallExpr, init ir.Nodes) *ir.InlinedCallExpr { … }

// rewriteInterfaceCall devirtualizes the given interface call using a direct
// method call to concretetyp.
func rewriteInterfaceCall(call *ir.CallExpr, curfn, callee *ir.Func, concretetyp *types.Type) ir.Node { … }

// rewriteFunctionCall devirtualizes the given OCALLFUNC using a direct
// function call to callee.
func rewriteFunctionCall(call *ir.CallExpr, curfn, callee *ir.Func) ir.Node { … }

// methodRecvType returns the type containing method fn. Returns nil if fn
// is not a method.
func methodRecvType(fn *ir.Func) *types.Type { … }

// interfaceCallRecvTypeAndMethod returns the type and the method of the interface
// used in an interface call.
func interfaceCallRecvTypeAndMethod(call *ir.CallExpr) (*types.Type, *types.Sym) { … }

// findHotConcreteCallee returns the *ir.Func of the hottest callee of a call,
// if available, and its edge weight. extraFn can perform additional
// applicability checks on each candidate edge. If extraFn returns false,
// candidate will not be considered a valid callee candidate.
func findHotConcreteCallee(p *pgoir.Profile, caller *ir.Func, call *ir.CallExpr, extraFn func(callerName string, callOffset int, candidate *pgoir.IREdge) bool) (*ir.Func, int64) { … }

// findHotConcreteInterfaceCallee returns the *ir.Func of the hottest callee of an
// interface call, if available, and its edge weight.
func findHotConcreteInterfaceCallee(p *pgoir.Profile, caller *ir.Func, call *ir.CallExpr) (*ir.Func, int64) { … }

// findHotConcreteFunctionCallee returns the *ir.Func of the hottest callee of an
// indirect function call, if available, and its edge weight.
func findHotConcreteFunctionCallee(p *pgoir.Profile, caller *ir.Func, call *ir.CallExpr) (*ir.Func, int64) { … }