cmd/compile: re-enable nilcheck removal for newobject

Also add compiler debug ouput and add a test.

Fixes #15390.

Change-Id: Iceba1414c29bcc213b87837387bf8ded1f3157f1
Reviewed-on: https://go-review.googlesource.com/30011
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/test/nilptr3.go b/test/nilptr3.go
index b965cd262d..8fdae8c075 100644
--- a/test/nilptr3.go
+++ b/test/nilptr3.go
@@ -247,3 +247,10 @@ func f(t *TT) *byte {
 	s := &t.SS  // ERROR "removed nil check"
 	return &s.x // ERROR "generated nil check"
 }
+
+// make sure not to do nil check for newobject
+func f7() (*Struct, float64) {
+	t := new(Struct)
+	p := &t.Y    // ERROR "removed nil check"
+	return t, *p // ERROR "removed nil check"
+}