[dev.typeparams] cmd/compile: simplify ~r/~b naming

The compiler renames anonymous and blank result parameters to ~rN or
~bN, but the current semantics for computing N are rather annoying and
difficult to reproduce cleanly. They also lead to difficult to read
escape analysis results in tests.

This CL changes N to always be calculated as the parameter's index
within the function's result parameter tuple. E.g., if a function has
a single result, it will now always be named "~r0".

The normative change to this CL is fairly simple, but it requires
updating a lot of test expectations.

Change-Id: I58a3c94de00cb822cb94efe52d115531193c993c
Reviewed-on: https://go-review.googlesource.com/c/go/+/323010
Trust: Matthew Dempsky <mdempsky@google.com>
Trust: Dan Scales <danscales@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Dan Scales <danscales@google.com>

1 files changed, 8 insertions, 8 deletions

diff --git a/test/escape_array.go b/test/escape_array.go
index 0d07fd861f..83062c9436 100644
--- a/test/escape_array.go
+++ b/test/escape_array.go
@@ -12,15 +12,15 @@ var Ssink *string
 
 type U [2]*string
 
-func bar(a, b *string) U { // ERROR "leaking param: a to result ~r2 level=0$" "leaking param: b to result ~r2 level=0$"
+func bar(a, b *string) U { // ERROR "leaking param: a to result ~r0 level=0$" "leaking param: b to result ~r0 level=0$"
 	return U{a, b}
 }
 
-func foo(x U) U { // ERROR "leaking param: x to result ~r1 level=0$"
+func foo(x U) U { // ERROR "leaking param: x to result ~r0 level=0$"
 	return U{x[1], x[0]}
 }
 
-func bff(a, b *string) U { // ERROR "leaking param: a to result ~r2 level=0$" "leaking param: b to result ~r2 level=0$"
+func bff(a, b *string) U { // ERROR "leaking param: a to result ~r0 level=0$" "leaking param: b to result ~r0 level=0$"
 	return foo(foo(bar(a, b)))
 }
 
@@ -41,27 +41,27 @@ func tbff2() *string {
 	return u[1]
 }
 
-func car(x U) *string { // ERROR "leaking param: x to result ~r1 level=0$"
+func car(x U) *string { // ERROR "leaking param: x to result ~r0 level=0$"
 	return x[0]
 }
 
 // BAD: need fine-grained analysis to track x[0] and x[1] differently.
-func fun(x U, y *string) *string { // ERROR "leaking param: x to result ~r2 level=0$" "leaking param: y to result ~r2 level=0$"
+func fun(x U, y *string) *string { // ERROR "leaking param: x to result ~r0 level=0$" "leaking param: y to result ~r0 level=0$"
 	x[0] = y
 	return x[1]
 }
 
-func fup(x *U, y *string) *string { // ERROR "leaking param: x to result ~r2 level=1$" "leaking param: y$"
+func fup(x *U, y *string) *string { // ERROR "leaking param: x to result ~r0 level=1$" "leaking param: y$"
 	x[0] = y // leaking y to heap is intended
 	return x[1]
 }
 
-func fum(x *U, y **string) *string { // ERROR "leaking param: x to result ~r2 level=1$" "leaking param content: y$"
+func fum(x *U, y **string) *string { // ERROR "leaking param: x to result ~r0 level=1$" "leaking param content: y$"
 	x[0] = *y
 	return x[1]
 }
 
-func fuo(x *U, y *U) *string { // ERROR "leaking param: x to result ~r2 level=1$" "leaking param content: y$"
+func fuo(x *U, y *U) *string { // ERROR "leaking param: x to result ~r0 level=1$" "leaking param content: y$"
 	x[0] = y[0]
 	return x[1]
 }