From d36a6bf44da6d9b6e1ec355381ef15d253435e20 Mon Sep 17 00:00:00 2001 From: Matthew Dempsky Date: Sat, 2 Jan 2021 23:56:20 -0800 Subject: [PATCH] [dev.regabi] cmd/compile: improve walkReturn common case Instead of evaluating all result expressions up front and then assigning them to their result destinations, we can interleave evaluation with assignment. This reduces how much temporary stack/register space is needed to hold the values in flight. Doesn't pass toolstash -cmp, because it allows better return statement code to be generated. E.g., cmd/go's text segment on linux/ppc64le shrinks another 1kB. Change-Id: I3fe889342c80e947e0118704ec01f1682c577e6e Reviewed-on: https://go-review.googlesource.com/c/go/+/281153 Trust: Matthew Dempsky Run-TryBot: Matthew Dempsky TryBot-Result: Go Bot Reviewed-by: Cuong Manh Le --- src/cmd/compile/internal/walk/assign.go | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/src/cmd/compile/internal/walk/assign.go b/src/cmd/compile/internal/walk/assign.go index 04bd576b696..84ba7f0dc50 100644 --- a/src/cmd/compile/internal/walk/assign.go +++ b/src/cmd/compile/internal/walk/assign.go @@ -253,10 +253,9 @@ func walkReturn(n *ir.ReturnStmt) ir.Node { // Common case: Assignment order doesn't matter. Simply assign to // each result parameter in order. - walkExprList(n.Results, n.PtrInit()) - res := make([]ir.Node, len(results)) + var res ir.Nodes for i, v := range n.Results { - res[i] = convas(ir.NewAssignStmt(base.Pos, dsts[i], v), n.PtrInit()) + appendWalkStmt(&res, convas(ir.NewAssignStmt(base.Pos, dsts[i], v), &res)) } n.Results = res return n