From: go101 <tapir.liu@gmail.com>
Date: Fri, 2 Jul 2021 08:01:20 +0000 (+0000)
Subject: cmd/compile: fix stack growing algorithm
X-Git-Tag: go1.17rc1~14
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=287c5e8066;p=gostls13.git

cmd/compile: fix stack growing algorithm

The current stack growing implementation looks not right.
Specially, the line runtime/stack.go#L1068 never gets executed,
which causes many unnecessary copystack calls.

This PR is trying to correct the implementation.
As I'm not familiar with the code, the fix is just a guess.

Change-Id: I0bea1148175fad34f74f19d455c240c94d3cb78b
GitHub-Last-Rev: 57205f91fe6f7cecbf0b7aad0d90d2f81270b1e8
GitHub-Pull-Request: golang/go#47010
Reviewed-on: https://go-review.googlesource.com/c/go/+/332229
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Dmitri Shuralyov <dmitshur@golang.org>
---

diff --git a/src/runtime/stack.go b/src/runtime/stack.go
index b21c9c9518..6e0d157630 100644
--- a/src/runtime/stack.go
+++ b/src/runtime/stack.go
@@ -1064,7 +1064,9 @@ func newstack() {
 	// recheck the bounds on return.)
 	if f := findfunc(gp.sched.pc); f.valid() {
 		max := uintptr(funcMaxSPDelta(f))
-		for newsize-gp.sched.sp < max+_StackGuard {
+		needed := max + _StackGuard
+		used := gp.stack.hi - gp.sched.sp
+		for newsize-used < needed {
 			newsize *= 2
 		}
 	}