From f2e8d7112cbe9a05d411c23a98cb99edfcf45369 Mon Sep 17 00:00:00 2001
From: Ayke van Laethem <aykevanlaethem@gmail.com>
Date: Fri, 4 Jun 2021 14:43:25 +0200
Subject: [PATCH] compiler: refactor method names

This commit includes two changes:

  * It makes unexported interface methods package-private, so that it's
    not possible to type-assert on an unexported method in a different
    package.
  * It makes the globals used to identify interface methods defined
    globals, so that they can (eventually) be left in the program for an
    eventual non-LTO build mode.
---
 compiler/compiler.go                         |  2 +-
 compiler/interface.go                        | 15 +++++++++++++--
 compiler/testdata/interface.ll               | 12 ++++++------
 transform/interface-lowering.go              | 10 +++++++---
 transform/rtcalls.go                         |  2 +-
 transform/testdata/interface.ll              | 12 ++++++------
 transform/testdata/reflect-implements.ll     | 14 +++++++-------
 transform/testdata/reflect-implements.out.ll | 12 ++++++------
 8 files changed, 47 insertions(+), 32 deletions(-)

diff --git a/compiler/compiler.go b/compiler/compiler.go
index f25832ac..925b61bf 100644
--- a/compiler/compiler.go
+++ b/compiler/compiler.go
@@ -23,7 +23,7 @@ import (
 // Version of the compiler pacakge. Must be incremented each time the compiler
 // package changes in a way that affects the generated LLVM module.
 // This version is independent of the TinyGo version number.
-const Version = 10 // last change: context parameter in go wrapper
+const Version = 11 // last change: change method name globals
 
 func init() {
 	llvm.InitializeAllTargets()
diff --git a/compiler/interface.go b/compiler/interface.go
index eda7e365..5d8895d7 100644
--- a/compiler/interface.go
+++ b/compiler/interface.go
@@ -311,10 +311,21 @@ func (c *compilerContext) getInterfaceMethodSet(typ types.Type) llvm.Value {
 // used during the interface lowering pass.
 func (c *compilerContext) getMethodSignature(method *types.Func) llvm.Value {
 	signature := methodSignature(method)
-	signatureGlobal := c.mod.NamedGlobal("func " + signature)
+	var globalName string
+	if token.IsExported(method.Name()) {
+		globalName = "reflect/methods." + signature
+	} else {
+		globalName = method.Type().(*types.Signature).Recv().Pkg().Path() + ".$methods." + signature
+	}
+	signatureGlobal := c.mod.NamedGlobal(globalName)
 	if signatureGlobal.IsNil() {
-		signatureGlobal = llvm.AddGlobal(c.mod, c.ctx.Int8Type(), "func "+signature)
+		// TODO: put something useful in these globals, such as the method
+		// signature. Useful to one day implement reflect.Value.Method(n).
+		signatureGlobal = llvm.AddGlobal(c.mod, c.ctx.Int8Type(), globalName)
+		signatureGlobal.SetInitializer(llvm.ConstInt(c.ctx.Int8Type(), 0, false))
+		signatureGlobal.SetLinkage(llvm.LinkOnceODRLinkage)
 		signatureGlobal.SetGlobalConstant(true)
+		signatureGlobal.SetAlignment(1)
 	}
 	return signatureGlobal
 }
diff --git a/compiler/testdata/interface.ll b/compiler/testdata/interface.ll
index eb217bdc..be9e229a 100644
--- a/compiler/testdata/interface.ll
+++ b/compiler/testdata/interface.ll
@@ -13,15 +13,15 @@ target triple = "wasm32--wasi"
 @"reflect/types.type:pointer:named:error" = linkonce_odr constant %runtime.typecodeID { %runtime.typecodeID* @"reflect/types.type:named:error", i32 0, %runtime.interfaceMethodInfo* null, %runtime.typecodeID* null }
 @"reflect/types.type:named:error" = linkonce_odr constant %runtime.typecodeID { %runtime.typecodeID* @"reflect/types.type:interface:{Error:func:{}{basic:string}}", i32 0, %runtime.interfaceMethodInfo* null, %runtime.typecodeID* @"reflect/types.type:pointer:named:error" }
 @"reflect/types.type:interface:{Error:func:{}{basic:string}}" = linkonce_odr constant %runtime.typecodeID { %runtime.typecodeID* bitcast ([1 x i8*]* @"reflect/types.interface:interface{Error() string}$interface" to %runtime.typecodeID*), i32 0, %runtime.interfaceMethodInfo* null, %runtime.typecodeID* @"reflect/types.type:pointer:interface:{Error:func:{}{basic:string}}" }
-@"func Error() string" = external constant i8
-@"reflect/types.interface:interface{Error() string}$interface" = linkonce_odr constant [1 x i8*] [i8* @"func Error() string"]
+@"reflect/methods.Error() string" = linkonce_odr constant i8 0, align 1
+@"reflect/types.interface:interface{Error() string}$interface" = linkonce_odr constant [1 x i8*] [i8* @"reflect/methods.Error() string"]
 @"reflect/types.type:pointer:interface:{Error:func:{}{basic:string}}" = linkonce_odr constant %runtime.typecodeID { %runtime.typecodeID* @"reflect/types.type:interface:{Error:func:{}{basic:string}}", i32 0, %runtime.interfaceMethodInfo* null, %runtime.typecodeID* null }
 @"reflect/types.type:pointer:interface:{String:func:{}{basic:string}}" = linkonce_odr constant %runtime.typecodeID { %runtime.typecodeID* @"reflect/types.type:interface:{String:func:{}{basic:string}}", i32 0, %runtime.interfaceMethodInfo* null, %runtime.typecodeID* null }
 @"reflect/types.type:interface:{String:func:{}{basic:string}}" = linkonce_odr constant %runtime.typecodeID { %runtime.typecodeID* bitcast ([1 x i8*]* @"reflect/types.interface:interface{String() string}$interface" to %runtime.typecodeID*), i32 0, %runtime.interfaceMethodInfo* null, %runtime.typecodeID* @"reflect/types.type:pointer:interface:{String:func:{}{basic:string}}" }
-@"func String() string" = external constant i8
-@"reflect/types.interface:interface{String() string}$interface" = linkonce_odr constant [1 x i8*] [i8* @"func String() string"]
+@"reflect/methods.String() string" = linkonce_odr constant i8 0, align 1
+@"reflect/types.interface:interface{String() string}$interface" = linkonce_odr constant [1 x i8*] [i8* @"reflect/methods.String() string"]
 @"reflect/types.typeid:basic:int" = external constant i8
-@"error$interface" = linkonce_odr constant [1 x i8*] [i8* @"func Error() string"]
+@"error$interface" = linkonce_odr constant [1 x i8*] [i8* @"reflect/methods.Error() string"]
 
 declare noalias nonnull i8* @runtime.alloc(i32, i8*, i8*)
 
@@ -92,7 +92,7 @@ typeassert.next:                                  ; preds = %typeassert.ok, %ent
 
 define hidden %runtime._string @main.callErrorMethod(i32 %itf.typecode, i8* %itf.value, i8* %context, i8* %parentHandle) unnamed_addr {
 entry:
-  %invoke.func = call i32 @runtime.interfaceMethod(i32 %itf.typecode, i8** getelementptr inbounds ([1 x i8*], [1 x i8*]* @"error$interface", i32 0, i32 0), i8* nonnull @"func Error() string", i8* undef, i8* null)
+  %invoke.func = call i32 @runtime.interfaceMethod(i32 %itf.typecode, i8** getelementptr inbounds ([1 x i8*], [1 x i8*]* @"error$interface", i32 0, i32 0), i8* nonnull @"reflect/methods.Error() string", i8* undef, i8* null)
   %invoke.func.cast = inttoptr i32 %invoke.func to %runtime._string (i8*, i8*, i8*)*
   %0 = call %runtime._string %invoke.func.cast(i8* %itf.value, i8* undef, i8* undef)
   ret %runtime._string %0
diff --git a/transform/interface-lowering.go b/transform/interface-lowering.go
index 79b3361a..57c8c76d 100644
--- a/transform/interface-lowering.go
+++ b/transform/interface-lowering.go
@@ -54,10 +54,14 @@ type signatureInfo struct {
 // methodName takes a method name like "func String()" and returns only the
 // name, which is "String" in this case.
 func (s *signatureInfo) methodName() string {
-	if !strings.HasPrefix(s.name, "func ") {
-		panic("signature must start with \"func \"")
+	var methodName string
+	if strings.HasPrefix(s.name, "reflect/methods.") {
+		methodName = s.name[len("reflect/methods."):]
+	} else if idx := strings.LastIndex(s.name, ".$methods."); idx >= 0 {
+		methodName = s.name[idx+len(".$methods."):]
+	} else {
+		panic("could not find method name")
 	}
-	methodName := s.name[len("func "):]
 	if openingParen := strings.IndexByte(methodName, '('); openingParen < 0 {
 		panic("no opening paren in signature name")
 	} else {
diff --git a/transform/rtcalls.go b/transform/rtcalls.go
index 0ced0bfe..c10b3c28 100644
--- a/transform/rtcalls.go
+++ b/transform/rtcalls.go
@@ -105,7 +105,7 @@ func OptimizeStringEqual(mod llvm.Module) {
 // As of this writing, the (reflect.Type).Interface method has not yet been
 // implemented so this optimization is critical for the encoding/json package.
 func OptimizeReflectImplements(mod llvm.Module) {
-	implementsSignature := mod.NamedGlobal("func Implements(reflect.Type) bool")
+	implementsSignature := mod.NamedGlobal("reflect/methods.Implements(reflect.Type) bool")
 	if implementsSignature.IsNil() {
 		return
 	}
diff --git a/transform/testdata/interface.ll b/transform/testdata/interface.ll
index c67595a2..2101725a 100644
--- a/transform/testdata/interface.ll
+++ b/transform/testdata/interface.ll
@@ -8,11 +8,11 @@ target triple = "armv7m-none-eabi"
 @"reflect/types.typeid:basic:uint8" = external constant i8
 @"reflect/types.typeid:basic:int16" = external constant i8
 @"reflect/types.type:basic:int" = private constant %runtime.typecodeID zeroinitializer
-@"func NeverImplementedMethod()" = external constant i8
-@"Unmatched$interface" = private constant [1 x i8*] [i8* @"func NeverImplementedMethod()"]
-@"func Double() int" = external constant i8
-@"Doubler$interface" = private constant [1 x i8*] [i8* @"func Double() int"]
-@"Number$methodset" = private constant [1 x %runtime.interfaceMethodInfo] [%runtime.interfaceMethodInfo { i8* @"func Double() int", i32 ptrtoint (i32 (i8*, i8*)* @"(Number).Double$invoke" to i32) }]
+@"reflect/methods.NeverImplementedMethod()" = linkonce_odr constant i8 0
+@"Unmatched$interface" = private constant [1 x i8*] [i8* @"reflect/methods.NeverImplementedMethod()"]
+@"reflect/methods.Double() int" = linkonce_odr constant i8 0
+@"Doubler$interface" = private constant [1 x i8*] [i8* @"reflect/methods.Double() int"]
+@"Number$methodset" = private constant [1 x %runtime.interfaceMethodInfo] [%runtime.interfaceMethodInfo { i8* @"reflect/methods.Double() int", i32 ptrtoint (i32 (i8*, i8*)* @"(Number).Double$invoke" to i32) }]
 @"reflect/types.type:named:Number" = private constant %runtime.typecodeID { %runtime.typecodeID* @"reflect/types.type:basic:int", i32 0, %runtime.interfaceMethodInfo* getelementptr inbounds ([1 x %runtime.interfaceMethodInfo], [1 x %runtime.interfaceMethodInfo]* @"Number$methodset", i32 0, i32 0) }
 
 declare i1 @runtime.interfaceImplements(i32, i8**)
@@ -48,7 +48,7 @@ typeswitch.notUnmatched:
   br i1 %isDoubler, label %typeswitch.Doubler, label %typeswitch.notDoubler
 
 typeswitch.Doubler:
-  %doubler.func = call i32 @runtime.interfaceMethod(i32 %typecode, i8** getelementptr inbounds ([1 x i8*], [1 x i8*]* @"Doubler$interface", i32 0, i32 0), i8* nonnull @"func Double() int")
+  %doubler.func = call i32 @runtime.interfaceMethod(i32 %typecode, i8** getelementptr inbounds ([1 x i8*], [1 x i8*]* @"Doubler$interface", i32 0, i32 0), i8* nonnull @"reflect/methods.Double() int")
   %doubler.func.cast = inttoptr i32 %doubler.func to i32 (i8*, i8*)*
   %doubler.result = call i32 %doubler.func.cast(i8* %value, i8* null)
   call void @runtime.printint32(i32 %doubler.result)
diff --git a/transform/testdata/reflect-implements.ll b/transform/testdata/reflect-implements.ll
index 22c76485..29f38243 100644
--- a/transform/testdata/reflect-implements.ll
+++ b/transform/testdata/reflect-implements.ll
@@ -6,11 +6,11 @@ target triple = "i686--linux"
 
 @"reflect/types.type:named:error" = linkonce_odr constant %runtime.typecodeID { %runtime.typecodeID* @"reflect/types.type:interface:{Error:func:{}{basic:string}}", i32 0, %runtime.interfaceMethodInfo* null }
 @"reflect/types.type:interface:{Error:func:{}{basic:string}}" = linkonce_odr constant %runtime.typecodeID { %runtime.typecodeID* bitcast ([1 x i8*]* @"reflect/types.interface:interface{Error() string}$interface" to %runtime.typecodeID*), i32 0, %runtime.interfaceMethodInfo* null }
-@"func Error() string" = external constant i8
-@"reflect/types.interface:interface{Error() string}$interface" = linkonce_odr constant [1 x i8*] [i8* @"func Error() string"]
-@"func Align() int" = external constant i8
-@"func Implements(reflect.Type) bool" = external constant i8
-@"reflect.Type$interface" = linkonce_odr constant [2 x i8*] [i8* @"func Align() int", i8* @"func Implements(reflect.Type) bool"]
+@"reflect/methods.Error() string" = linkonce_odr constant i8 0
+@"reflect/types.interface:interface{Error() string}$interface" = linkonce_odr constant [1 x i8*] [i8* @"reflect/methods.Error() string"]
+@"reflect/methods.Align() int" = linkonce_odr constant i8 0
+@"reflect/methods.Implements(reflect.Type) bool" = linkonce_odr constant i8 0
+@"reflect.Type$interface" = linkonce_odr constant [2 x i8*] [i8* @"reflect/methods.Align() int", i8* @"reflect/methods.Implements(reflect.Type) bool"]
 @"reflect/types.type:named:reflect.rawType" = linkonce_odr constant %runtime.typecodeID { %runtime.typecodeID* @"reflect/types.type:basic:uintptr", i32 0, %runtime.interfaceMethodInfo* getelementptr inbounds ([20 x %runtime.interfaceMethodInfo], [20 x %runtime.interfaceMethodInfo]* @"reflect.rawType$methodset", i32 0, i32 0) }
 @"reflect.rawType$methodset" = linkonce_odr constant [20 x %runtime.interfaceMethodInfo] zeroinitializer
 @"reflect/types.type:basic:uintptr" = linkonce_odr constant %runtime.typecodeID zeroinitializer
@@ -28,7 +28,7 @@ declare i32 @runtime.interfaceMethod(i32, i8**, i8*, i8*, i8*)
 ; known at compile time (after the interp pass has run).
 define i1 @main.isError(i32 %typ.typecode, i8* %typ.value, i8* %context, i8* %parentHandle) {
 entry:
-  %invoke.func = call i32 @runtime.interfaceMethod(i32 %typ.typecode, i8** getelementptr inbounds ([2 x i8*], [2 x i8*]* @"reflect.Type$interface", i32 0, i32 0), i8* nonnull @"func Implements(reflect.Type) bool", i8* undef, i8* null)
+  %invoke.func = call i32 @runtime.interfaceMethod(i32 %typ.typecode, i8** getelementptr inbounds ([2 x i8*], [2 x i8*]* @"reflect.Type$interface", i32 0, i32 0), i8* nonnull @"reflect/methods.Implements(reflect.Type) bool", i8* undef, i8* null)
   %invoke.func.cast = inttoptr i32 %invoke.func to i1 (i8*, i32, i8*, i8*, i8*)*
   %result = call i1 %invoke.func.cast(i8* %typ.value, i32 ptrtoint (%runtime.typecodeID* @"reflect/types.type:named:reflect.rawType" to i32), i8* bitcast (%runtime.typecodeID* @"reflect/types.type:named:error" to i8*), i8* undef, i8* undef)
   ret i1 %result
@@ -41,7 +41,7 @@ entry:
 ; }
 define i1 @main.isUnknown(i32 %typ.typecode, i8* %typ.value, i32 %itf.typecode, i8* %itf.value, i8* %context, i8* %parentHandle) {
 entry:
-  %invoke.func = call i32 @runtime.interfaceMethod(i32 %typ.typecode, i8** getelementptr inbounds ([2 x i8*], [2 x i8*]* @"reflect.Type$interface", i32 0, i32 0), i8* nonnull @"func Implements(reflect.Type) bool", i8* undef, i8* null)
+  %invoke.func = call i32 @runtime.interfaceMethod(i32 %typ.typecode, i8** getelementptr inbounds ([2 x i8*], [2 x i8*]* @"reflect.Type$interface", i32 0, i32 0), i8* nonnull @"reflect/methods.Implements(reflect.Type) bool", i8* undef, i8* null)
   %invoke.func.cast = inttoptr i32 %invoke.func to i1 (i8*, i32, i8*, i8*, i8*)*
   %result = call i1 %invoke.func.cast(i8* %typ.value, i32 %itf.typecode, i8* %itf.value, i8* undef, i8* undef)
   ret i1 %result
diff --git a/transform/testdata/reflect-implements.out.ll b/transform/testdata/reflect-implements.out.ll
index 03d97769..f1bc92c1 100644
--- a/transform/testdata/reflect-implements.out.ll
+++ b/transform/testdata/reflect-implements.out.ll
@@ -6,11 +6,11 @@ target triple = "i686--linux"
 
 @"reflect/types.type:named:error" = linkonce_odr constant %runtime.typecodeID { %runtime.typecodeID* @"reflect/types.type:interface:{Error:func:{}{basic:string}}", i32 0, %runtime.interfaceMethodInfo* null }
 @"reflect/types.type:interface:{Error:func:{}{basic:string}}" = linkonce_odr constant %runtime.typecodeID { %runtime.typecodeID* bitcast ([1 x i8*]* @"reflect/types.interface:interface{Error() string}$interface" to %runtime.typecodeID*), i32 0, %runtime.interfaceMethodInfo* null }
-@"func Error() string" = external constant i8
-@"reflect/types.interface:interface{Error() string}$interface" = linkonce_odr constant [1 x i8*] [i8* @"func Error() string"]
-@"func Align() int" = external constant i8
-@"func Implements(reflect.Type) bool" = external constant i8
-@"reflect.Type$interface" = linkonce_odr constant [2 x i8*] [i8* @"func Align() int", i8* @"func Implements(reflect.Type) bool"]
+@"reflect/methods.Error() string" = linkonce_odr constant i8 0
+@"reflect/types.interface:interface{Error() string}$interface" = linkonce_odr constant [1 x i8*] [i8* @"reflect/methods.Error() string"]
+@"reflect/methods.Align() int" = linkonce_odr constant i8 0
+@"reflect/methods.Implements(reflect.Type) bool" = linkonce_odr constant i8 0
+@"reflect.Type$interface" = linkonce_odr constant [2 x i8*] [i8* @"reflect/methods.Align() int", i8* @"reflect/methods.Implements(reflect.Type) bool"]
 @"reflect/types.type:named:reflect.rawType" = linkonce_odr constant %runtime.typecodeID { %runtime.typecodeID* @"reflect/types.type:basic:uintptr", i32 0, %runtime.interfaceMethodInfo* getelementptr inbounds ([20 x %runtime.interfaceMethodInfo], [20 x %runtime.interfaceMethodInfo]* @"reflect.rawType$methodset", i32 0, i32 0) }
 @"reflect.rawType$methodset" = linkonce_odr constant [20 x %runtime.interfaceMethodInfo] zeroinitializer
 @"reflect/types.type:basic:uintptr" = linkonce_odr constant %runtime.typecodeID zeroinitializer
@@ -28,7 +28,7 @@ entry:
 
 define i1 @main.isUnknown(i32 %typ.typecode, i8* %typ.value, i32 %itf.typecode, i8* %itf.value, i8* %context, i8* %parentHandle) {
 entry:
-  %invoke.func = call i32 @runtime.interfaceMethod(i32 %typ.typecode, i8** getelementptr inbounds ([2 x i8*], [2 x i8*]* @"reflect.Type$interface", i32 0, i32 0), i8* nonnull @"func Implements(reflect.Type) bool", i8* undef, i8* null)
+  %invoke.func = call i32 @runtime.interfaceMethod(i32 %typ.typecode, i8** getelementptr inbounds ([2 x i8*], [2 x i8*]* @"reflect.Type$interface", i32 0, i32 0), i8* nonnull @"reflect/methods.Implements(reflect.Type) bool", i8* undef, i8* null)
   %invoke.func.cast = inttoptr i32 %invoke.func to i1 (i8*, i32, i8*, i8*, i8*)*
   %result = call i1 %invoke.func.cast(i8* %typ.value, i32 %itf.typecode, i8* %itf.value, i8* undef, i8* undef)
   ret i1 %result