cmd/compile: escape analysis, don't always escape variadic args

Turns out the summary information for the ... args was
already correctly computed, all that lacked was to make
use of it and correct tests that documented our prior
deficiencies.

Fixes #12006

Change-Id: Ie8adfab7547f179391d470679598f0904aabf9f7
Reviewed-on: https://go-review.googlesource.com/15200
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>

1 files changed, 15 insertions, 19 deletions

diff --git a/test/escape2.go b/test/escape2.go
index 46cfde4a94..d17a919a11 100644
--- a/test/escape2.go
+++ b/test/escape2.go
@@ -620,15 +620,15 @@ func myprint1(y *int, x ...interface{}) *interface{} { // ERROR "leaking param:
 }
 
 func foo75(z *int) { // ERROR "foo75 z does not escape$"
-	myprint(z, 1, 2, 3) // ERROR "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$" "foo75 ... argument does not escape$"
+	myprint(z, 1, 2, 3) // ERROR "1 does not escape" "2 does not escape" "3 does not escape" "foo75 ... argument does not escape$"
 }
 
 func foo75a(z *int) { // ERROR "foo75a z does not escape$"
-	myprint1(z, 1, 2, 3) // ERROR "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$" "foo75a ... argument does not escape$"
+	myprint1(z, 1, 2, 3) // ERROR "1 does not escape" "2 does not escape" "3 does not escape" "foo75a ... argument does not escape$"
 }
 
 func foo75esc(z *int) { // ERROR "leaking param: z$"
-	gxx = myprint(z, 1, 2, 3) // ERROR "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$" "foo75esc ... argument does not escape$"
+	gxx = myprint(z, 1, 2, 3) // ERROR "1 does not escape" "2 does not escape" "3 does not escape" "foo75esc ... argument does not escape$"
 }
 
 func foo75aesc(z *int) { // ERROR "foo75aesc z does not escape$"
@@ -640,30 +640,28 @@ func foo75aesc1(z *int) { // ERROR "foo75aesc1 z does not escape$"
 	sink = myprint1(z, 1, 2, 3) // ERROR "... argument escapes to heap$" "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$" "myprint1\(z, 1, 2, 3\) escapes to heap$"
 }
 
-// BAD: z does not escape here
-func foo76(z *int) { // ERROR "leaking param: z$"
-	myprint(nil, z) // ERROR "foo76 ... argument does not escape$" "z escapes to heap$"
+func foo76(z *int) { // ERROR "z does not escape"
+	myprint(nil, z) // ERROR "foo76 ... argument does not escape$" "z does not escape"
 }
 
-// BAD: z does not escape here
-func foo76a(z *int) { // ERROR "leaking param: z$"
-	myprint1(nil, z) // ERROR "foo76a ... argument does not escape$" "z escapes to heap$"
+func foo76a(z *int) { // ERROR "z does not escape"
+	myprint1(nil, z) // ERROR "foo76a ... argument does not escape$" "z does not escape"
 }
 
 func foo76b() {
-	myprint(nil, 1, 2, 3) // ERROR "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$" "foo76b ... argument does not escape$"
+	myprint(nil, 1, 2, 3) // ERROR "1 does not escape" "2 does not escape" "3 does not escape" "foo76b ... argument does not escape$"
 }
 
 func foo76c() {
-	myprint1(nil, 1, 2, 3) // ERROR "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$" "foo76c ... argument does not escape$"
+	myprint1(nil, 1, 2, 3) // ERROR "1 does not escape" "2 does not escape" "3 does not escape" "foo76c ... argument does not escape$"
 }
 
 func foo76d() {
-	defer myprint(nil, 1, 2, 3) // ERROR "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$" "foo76d ... argument does not escape$"
+	defer myprint(nil, 1, 2, 3) // ERROR "1 does not escape" "2 does not escape" "3 does not escape" "foo76d ... argument does not escape$"
 }
 
 func foo76e() {
-	defer myprint1(nil, 1, 2, 3) // ERROR "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$" "foo76e ... argument does not escape$"
+	defer myprint1(nil, 1, 2, 3) // ERROR "1 does not escape" "2 does not escape" "3 does not escape" "foo76e ... argument does not escape$"
 }
 
 func foo76f() {
@@ -697,13 +695,11 @@ func foo77c(z []interface{}) { // ERROR "leaking param: z$"
 }
 
 func dotdotdot() {
-	// BAD: i should not escape here
-	i := 0           // ERROR "moved to heap: i$"
-	myprint(nil, &i) // ERROR "&i escapes to heap$" "dotdotdot ... argument does not escape$"
+	i := 0
+	myprint(nil, &i) // ERROR "&i does not escape" "dotdotdot ... argument does not escape$"
 
-	// BAD: j should not escape here
-	j := 0            // ERROR "moved to heap: j$"
-	myprint1(nil, &j) // ERROR "&j escapes to heap$" "dotdotdot ... argument does not escape$"
+	j := 0
+	myprint1(nil, &j) // ERROR "&j does not escape" "dotdotdot ... argument does not escape$"
 }
 
 func foo78(z int) *int { // ERROR "moved to heap: z$"