cmd/compile: do more type conversion inline

The code to do the conversion is smaller than the
call to the runtime.
The 1-result asserts need to call panic if they fail, but that
code is out of line.

The only conversions left in the runtime are those which
might allocate and those which might need to generate an itab.

Given the following types:
  type E interface{}
  type I interface { foo() }
  type I2 iterface { foo(); bar() }
  type Big [10]int
  func (b Big) foo() { ... }

This CL inlines the following conversions:

was assertE2T
  var e E = ...
  b := i.(Big)
was assertE2T2
  var e E = ...
  b, ok := i.(Big)
was assertI2T
  var i I = ...
  b := i.(Big)
was assertI2T2
  var i I = ...
  b, ok := i.(Big)
was assertI2E
  var i I = ...
  e := i.(E)
was assertI2E2
  var i I = ...
  e, ok := i.(E)

These are the remaining runtime calls:

convT2E:
  var b Big = ...
  var e E = b
convT2I:
  var b Big = ...
  var i I = b
convI2I:
  var i2 I2 = ...
  var i I = i2
assertE2I:
  var e E = ...
  i := e.(I)
assertE2I2:
  var e E = ...
  i, ok := e.(I)
assertI2I:
  var i I = ...
  i2 := i.(I2)
assertI2I2:
  var i I = ...
  i2, ok := i.(I2)

Fixes #17405
Fixes #8422

Change-Id: Ida2367bf8ce3cd2c6bb599a1814f1d275afabe21
Reviewed-on: https://go-review.googlesource.com/32313
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>

1 files changed, 0 insertions, 42 deletions

diff --git a/src/runtime/gc_test.go b/src/runtime/gc_test.go
index d53d3ee000..4a32f15167 100644
--- a/src/runtime/gc_test.go
+++ b/src/runtime/gc_test.go
@@ -5,7 +5,6 @@
 package runtime_test
 
 import (
-	"io"
 	"os"
 	"reflect"
 	"runtime"
@@ -399,37 +398,6 @@ func TestPrintGC(t *testing.T) {
 	close(done)
 }
 
-// The implicit y, ok := x.(error) for the case error
-// in testTypeSwitch used to not initialize the result y
-// before passing &y to assertE2I2GC.
-// Catch this by making assertE2I2 call runtime.GC,
-// which will force a stack scan and failure if there are
-// bad pointers, and then fill the stack with bad pointers
-// and run the type switch.
-func TestAssertE2I2Liveness(t *testing.T) {
-	// Note that this flag is defined in export_test.go
-	// and is not available to ordinary imports of runtime.
-	*runtime.TestingAssertE2I2GC = true
-	defer func() {
-		*runtime.TestingAssertE2I2GC = false
-	}()
-
-	poisonStack()
-	testTypeSwitch(io.EOF)
-	poisonStack()
-	testAssert(io.EOF)
-	poisonStack()
-	testAssertVar(io.EOF)
-}
-
-func poisonStack() uintptr {
-	var x [1000]uintptr
-	for i := range x {
-		x[i] = 0xff
-	}
-	return x[123]
-}
-
 func testTypeSwitch(x interface{}) error {
 	switch y := x.(type) {
 	case nil:
@@ -455,16 +423,6 @@ func testAssertVar(x interface{}) error {
 	return nil
 }
 
-func TestAssertE2T2Liveness(t *testing.T) {
-	*runtime.TestingAssertE2T2GC = true
-	defer func() {
-		*runtime.TestingAssertE2T2GC = false
-	}()
-
-	poisonStack()
-	testIfaceEqual(io.EOF)
-}
-
 var a bool
 
 //go:noinline