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cmd/compile: flag 'large' functions when -m=2+ in effect

When -m=N (where N > 1) is in effect, include a note in the trace
output if a given function is considered "big" during inlining
analysis, since this causes the inliner to be less aggressive. If a
small change to a large function happens to nudge it over the large
function threshold, it can be confusing for developers, thus it's
probably worth including this info in the remark output.

Change-Id: Id31a1b76371ab1ef9265ba28a377f97b0247d0a7
Reviewed-on: https://go-review.googlesource.com/c/go/+/460317
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Than McIntosh <thanm@google.com>
Reviewed-by: Keith Randall <khr@google.com>
This commit is contained in:
Than McIntosh
2023-01-03 13:11:10 -05:00
parent 1951857ec0
commit 733ba92187
2 changed files with 4 additions and 1 deletions
src/cmd/compile/internal/inline
test

@ -742,6 +742,9 @@ func InlineCalls(fn *ir.Func, profile *pgo.Profile) {
ir.CurFunc = fn
maxCost := int32(inlineMaxBudget)
if isBigFunc(fn) {
if base.Flag.LowerM > 1 {
fmt.Printf("%v: function %v considered 'big'; revising maxCost from %d to %d\n", ir.Line(fn), fn, maxCost, inlineBigFunctionMaxCost)
}
maxCost = inlineBigFunctionMaxCost
}
var inlCalls []*ir.InlinedCallExpr

@ -20,7 +20,7 @@ func medium(a []int) int { // ERROR "can inline medium with cost .* as:.*" "a do
return a[0] + a[1] + a[2] + a[3] + a[4] + a[5] + a[6] + a[7]
}
func f(a []int) int { // ERROR "cannot inline f:.*" "a does not escape"
func f(a []int) int { // ERROR "cannot inline f:.*" "a does not escape" "function f considered 'big'"
// Add lots of nodes to f's body. We need >5000.
// See cmd/compile/internal/gc/inl.go:inlineBigFunction*
a[0] = 0