From: Matthew Dempsky <mdempsky@google.com>
Date: Sun, 20 Dec 2020 03:26:06 +0000 (-0800)
Subject: [dev.regabi] cmd/compile: move itabname call out of implements
X-Git-Tag: go1.17beta1~1539^2~283
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=06915ac14dfb7c80f384e3446bc6fa474e6bfa94;p=gostls13.git

[dev.regabi] cmd/compile: move itabname call out of implements

We only need to call itabname when actually creating the OCONVIFACE
ops, not any time we test whether a type implements an
interface. Additionally, by moving this call out of implements, we
make it purely based on types, which makes it safe to move to package
types.

Does not pass toolstash -cmp, because it shuffles symbol creation
order.

Change-Id: Iea8e0c9374218f4d97b4339020ebd758d051bd03
Reviewed-on: https://go-review.googlesource.com/c/go/+/279333
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Matthew Dempsky <mdempsky@google.com>
---

diff --git a/src/cmd/compile/internal/gc/subr.go b/src/cmd/compile/internal/gc/subr.go
index 2b0047e150..48cbd2505e 100644
--- a/src/cmd/compile/internal/gc/subr.go
+++ b/src/cmd/compile/internal/gc/subr.go
@@ -304,6 +304,14 @@ func assignop(src, dst *types.Type) (ir.Op, string) {
 		var missing, have *types.Field
 		var ptr int
 		if implements(src, dst, &missing, &have, &ptr) {
+			// Call itabname so that (src, dst)
+			// gets added to itabs early, which allows
+			// us to de-virtualize calls through this
+			// type/interface pair later. See peekitabs in reflect.go
+			if isdirectiface(src) && !dst.IsEmptyInterface() {
+				itabname(src, dst)
+			}
+
 			return ir.OCONVIFACE, ""
 		}
 
@@ -1404,14 +1412,6 @@ func implements(t, iface *types.Type, m, samename **types.Field, ptr *int) bool
 		}
 	}
 
-	// We're going to emit an OCONVIFACE.
-	// Call itabname so that (t, iface)
-	// gets added to itabs early, which allows
-	// us to de-virtualize calls through this
-	// type/interface pair later. See peekitabs in reflect.go
-	if isdirectiface(t0) && !iface.IsEmptyInterface() {
-		itabname(t0, iface)
-	}
 	return true
 }