cmd/compile: prevent double-walk of switch for OPRINT/OPRINTN

When a println arg contains a call to an inlineable function
that itself contains a switch, that switch statement will be
walked twice, once by the walkexprlist formerly in the
OPRINT/OPRINTN case, then by walkexprlistcheap in walkprint.

Remove the first walkexprlist, it is not necessary.
walkexprlist =
		s[i] = walkexpr(s[i], init)
walkexprlistcheap = {
		s[i] = cheapexpr(n, init)
		s[i] = walkexpr(s[i], init)
}

Seems like this might be possible in other places, i.e.,
calls to inlineable switch-containing functions.

See also #25776.
Fixes #29220.

Change-Id: I3781e86aad6688711597b8bee9bc7ebd3af93601
Reviewed-on: https://go-review.googlesource.com/c/154497
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

diff --git a/src/cmd/compile/internal/gc/walk.go b/src/cmd/compile/internal/gc/walk.go
index b84bc26e04a720a7ef49a10d827a1bc304e923de..f23a5916479a6a069f2a5f3faf06c9216be0f876 100644 (file)
--- a/src/cmd/compile/internal/gc/walk.go
+++ b/src/cmd/compile/internal/gc/walk.go
@@ -563,7 +563,6 @@ opswitch:
                n = walkinrange(n, init)
 
        case OPRINT, OPRINTN:
-               walkexprlist(n.List.Slice(), init)
                n = walkprint(n, init)
 
        case OPANIC:

diff --git a/test/fixedbugs/issue29220.go b/test/fixedbugs/issue29220.go
new file mode 100644 (file)
index 0000000..bbfe930
--- /dev/null
+++ b/test/fixedbugs/issue29220.go
@@ -0,0 +1,26 @@
+// compile
+
+// Copyright 2018 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.
+
+package main
+
+func ascii(r rune) rune {
+       switch {
+       case 97 <= r && r <= 122:
+               return r - 32
+       case 65 <= r && r <= 90:
+               return r + 32
+       default:
+               return r
+       }
+}
+
+func main() {
+       nomeObjeto := "ABE1FK21"
+       println(string(nomeObjeto[1:4]))
+       println(ascii(rune(nomeObjeto[4])) >= 48 && ascii(rune(nomeObjeto[4])) <= 57)
+       println(string(nomeObjeto[5]))
+       println(string(nomeObjeto[6:10]))
+}