[go] cmd/compile: lower priority of avoiding registers

0 views

Skip to first unread message

Keith Randall (Gerrit)

unread,

Mar 28, 2023, 1:31:40 PM3/28/23

to Keith Randall, goph...@pubsubhelper.golang.org, golang-...@googlegroups.com, Keith Randall, Gopher Robot, Cherry Mui

Keith Randall submitted this change.

Approvals:
  Keith Randall: Run TryBots
  Keith Randall: Looks good to me, but someone else must approve
  Gopher Robot: TryBots succeeded
  Cherry Mui: Looks good to me, approved

cmd/compile: lower priority of avoiding registers

We avoid allocating registers when we know they may have a fixed use
later (arg/return value, or the CX shift argument to SHRQ, etc.) But
it isn't worth avoiding that register if it requires moving another
register.

A move we may have to do later is not worth a move we definitely have
to do now.

Fixes #59288

Change-Id: Ibbdcbaea9caee0c5f3e0d6956a1a084ba89757a9
Reviewed-on: https://go-review.googlesource.com/c/go/+/479895
Run-TryBot: Keith Randall <k...@golang.org>
TryBot-Result: Gopher Robot <go...@golang.org>
Reviewed-by: Cherry Mui <cher...@google.com>
Reviewed-by: Keith Randall <k...@google.com>
---
M src/cmd/compile/internal/ssa/regalloc.go
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/cmd/compile/internal/ssa/regalloc.go b/src/cmd/compile/internal/ssa/regalloc.go
index 2e121df..c7cdea2 100644
--- a/src/cmd/compile/internal/ssa/regalloc.go
+++ b/src/cmd/compile/internal/ssa/regalloc.go
@@ -1688,7 +1688,7 @@
 						}
 					}
 					// Avoid registers we're saving for other values.
-					if mask&^desired.avoid&^s.nospill != 0 {
+					if mask&^desired.avoid&^s.nospill&^s.used != 0 {
 						mask &^= desired.avoid
 					}
 					r := s.allocReg(mask, v)

To view, visit change 479895. To unsubscribe, or for help writing mail filters, visit settings.

Reply all

Reply to author

Forward

0 new messages