cmd/6g, cmd/8g: skip CONVNOP nodes in bgen.

Revision 3ae4607a43ff introduced CONVNOP layers
to fix type checking issues arising from comparisons.
The added complexity made 8g run out of registers
when compiling an equality function in go.net/ipv6.

A similar issue occurred in test/sizeof.go on
amd64p32 with 6g.

Fixes #7405.

LGTM=khr
R=rsc, dave, iant, khr
CC=golang-codereviews
https://golang.org/cl/78100044

diff --git a/src/cmd/6g/cgen.c b/src/cmd/6g/cgen.c
index 72ab0857e9f0abc26d2fe689d70f7a5184979ce9..102daa166df06f4714fb92b66bd0f52e06eb2642 100644 (file)
--- a/src/cmd/6g/cgen.c
+++ b/src/cmd/6g/cgen.c
@@ -1061,6 +1061,12 @@ bgen(Node *n, int true, int likely, Prog *to)
        }
        nr = N;
 
+       while(n->op == OCONVNOP) {
+               n = n->left;
+               if(n->ninit != nil)
+                       genlist(n->ninit);
+       }
+
        switch(n->op) {
        default:
        def:

diff --git a/src/cmd/8g/cgen.c b/src/cmd/8g/cgen.c
index 825c360de42acbf1ef9719a379c940eeb71d97e7..a357724a982dee3732675213d83589069198041a 100644 (file)
--- a/src/cmd/8g/cgen.c
+++ b/src/cmd/8g/cgen.c
@@ -935,6 +935,13 @@ bgen(Node *n, int true, int likely, Prog *to)
                patch(gins(AEND, N, N), to);
                return;
        }
+
+       while(n->op == OCONVNOP) {
+               n = n->left;
+               if(n->ninit != nil)
+                       genlist(n->ninit);
+       }
+
        nl = n->left;
        nr = N;
 

diff --git a/test/fixedbugs/issue7405.go b/test/fixedbugs/issue7405.go
new file mode 100644 (file)
index 0000000..52e1176
--- /dev/null
+++ b/test/fixedbugs/issue7405.go
@@ -0,0 +1,51 @@
+// compile
+
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Issue 7405: the equality function for struct with many
+// embedded fields became more complex after fixing issue 7366,
+// leading to out of registers on 386.
+
+package p
+
+type T1 struct {
+       T2
+       T3
+       T4
+}
+
+type T2 struct {
+       Conn
+}
+
+type T3 struct {
+       PacketConn
+}
+
+type T4 struct {
+       PacketConn
+       T5
+}
+
+type T5 struct {
+       x int
+       T6
+}
+
+type T6 struct {
+       y, z int
+}
+
+type Conn interface {
+       A()
+}
+
+type PacketConn interface {
+       B()
+}
+
+func F(a, b T1) bool {
+       return a == b
+}