cmd/compile: relax liveness restrictions on ambiguously live

Update gc liveness to remove special conservative treatment
of ambiguously live vars, since there is no longer a need to
protect against GCDEBUG=gcdead.

Change-Id: Id6e2d03218f7d67911e8436d283005a124e6957f
Reviewed-on: https://go-review.googlesource.com/24896
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>

1 files changed, 10 insertions, 9 deletions

diff --git a/test/live.go b/test/live.go
index b4d569a1ba..74548231dd 100644
--- a/test/live.go
+++ b/test/live.go
@@ -47,24 +47,25 @@ func f2(b bool) {
 }
 
 func f3(b1, b2 bool) {
-	// Because x and y are ambiguously live, they appear
-	// live throughout the function, to avoid being poisoned
-	// in GODEBUG=gcdead=1 mode.
+	// Here x and y are ambiguously live. In previous go versions they
+	// were marked as live throughout the function to avoid being
+	// poisoned in GODEBUG=gcdead=1 mode; this is now no longer the
+	// case.
 
-	printint(0) // ERROR "live at call to printint: x y$"
+	printint(0)
 	if b1 == false {
-		printint(0) // ERROR "live at call to printint: x y$"
+		printint(0)
 		return
 	}
 
 	if b2 {
 		var x *int
-		printpointer(&x) // ERROR "live at call to printpointer: x y$"
-		printpointer(&x) // ERROR "live at call to printpointer: x y$"
+		printpointer(&x) // ERROR "live at call to printpointer: x$"
+		printpointer(&x) // ERROR "live at call to printpointer: x$"
 	} else {
 		var y *int
-		printpointer(&y) // ERROR "live at call to printpointer: x y$"
-		printpointer(&y) // ERROR "live at call to printpointer: x y$"
+		printpointer(&y) // ERROR "live at call to printpointer: y$"
+		printpointer(&y) // ERROR "live at call to printpointer: y$"
 	}
 	printint(0) // ERROR "f3: x \(type \*int\) is ambiguously live$" "f3: y \(type \*int\) is ambiguously live$" "live at call to printint: x y$"
 }