From: Keith Randall <khr@golang.org>
Date: Wed, 16 Mar 2022 16:24:06 +0000 (-0700)
Subject: cmd/compile: allow noop conversions when comparing expressions
X-Git-Tag: go1.19beta1~1043
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=e5e638e512e1ec27673d5e01e99eb870899be7f7;p=gostls13.git

cmd/compile: allow noop conversions when comparing expressions

Allows mapclear optimization to trigger in more cases, including
some generic instantiations.

Fixes #51699

Change-Id: Ic54f7686e5fcb8fbcad640aa77ed326d7338b938
Reviewed-on: https://go-review.googlesource.com/c/go/+/393434
Trust: Keith Randall <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
---

diff --git a/src/cmd/compile/internal/ir/expr.go b/src/cmd/compile/internal/ir/expr.go
index ebb84ad78f..ff3cc8ed6e 100644
--- a/src/cmd/compile/internal/ir/expr.go
+++ b/src/cmd/compile/internal/ir/expr.go
@@ -973,6 +973,12 @@ var IsIntrinsicCall = func(*CallExpr) bool { return false }
 // lvalue expression is for OSLICE and OAPPEND optimizations, and it
 // is correct in those settings.
 func SameSafeExpr(l Node, r Node) bool {
+	for l.Op() == OCONVNOP {
+		l = l.(*ConvExpr).X
+	}
+	for r.Op() == OCONVNOP {
+		r = r.(*ConvExpr).X
+	}
 	if l.Op() != r.Op() || !types.Identical(l.Type(), r.Type()) {
 		return false
 	}
@@ -996,11 +1002,6 @@ func SameSafeExpr(l Node, r Node) bool {
 		r := r.(*UnaryExpr)
 		return SameSafeExpr(l.X, r.X)
 
-	case OCONVNOP:
-		l := l.(*ConvExpr)
-		r := r.(*ConvExpr)
-		return SameSafeExpr(l.X, r.X)
-
 	case OCONV:
 		l := l.(*ConvExpr)
 		r := r.(*ConvExpr)