compiler: refactor when the optsize attribute is set

This commit has a few related changes:

  * It sets the optsize attribute immediately in the compiler instead of
    adding it to each function afterwards in a loop. This seems to me
    like the more appropriate way to do it.
  * It centralizes setting the optsize attribute in the transform
    package, to make later changes easier.
  * It sets the optsize in a few more places: to runtime.initAll and to
    WebAssembly i64 wrappers.

This commit does not affect the binary size of any of the smoke tests,
so should be risk-free.

transform/interface-lowering.go

@@ -33,6 +33,7 @@ import (
 	"sort"
 	"strings"
 
+	"github.com/tinygo-org/tinygo/compileopts"
 	"tinygo.org/x/go-llvm"
 )
 
@@ -84,7 +85,7 @@ type interfaceInfo struct {
 // should be seen as a regular function call (see LowerInterfaces).
 type lowerInterfacesPass struct {
 	mod         llvm.Module
-	sizeLevel   int // LLVM optimization size level, 1 means -opt=s and 2 means -opt=z
+	config      *compileopts.Config
 	builder     llvm.Builder
 	ctx         llvm.Context
 	uintptrType llvm.Type
@@ -97,10 +98,10 @@ type lowerInterfacesPass struct {
 // emitted by the compiler as higher-level intrinsics. They need some lowering
 // before LLVM can work on them. This is done so that a few cleanup passes can
 // run before assigning the final type codes.
-func LowerInterfaces(mod llvm.Module, sizeLevel int) error {
+func LowerInterfaces(mod llvm.Module, config *compileopts.Config) error {
 	p := &lowerInterfacesPass{
 		mod:         mod,
-		sizeLevel:   sizeLevel,
+		config:      config,
 		builder:     mod.Context().NewBuilder(),
 		ctx:         mod.Context(),
 		uintptrType: mod.Context().IntType(llvm.NewTargetData(mod.DataLayout()).PointerSize() * 8),
@@ -343,9 +344,7 @@ func (p *lowerInterfacesPass) defineInterfaceImplementsFunc(fn llvm.Value, itf *
 	fn.Param(0).SetName("actualType")
 	fn.SetLinkage(llvm.InternalLinkage)
 	fn.SetUnnamedAddr(true)
-	if p.sizeLevel >= 2 {
-		fn.AddFunctionAttr(p.ctx.CreateEnumAttribute(llvm.AttributeKindID("optsize"), 0))
-	}
+	AddStandardAttributes(fn, p.config)
 
 	// Start the if/else chain at the entry block.
 	entry := p.ctx.AddBasicBlock(fn, "entry")
@@ -389,9 +388,7 @@ func (p *lowerInterfacesPass) defineInterfaceMethodFunc(fn llvm.Value, itf *inte
 	parentHandle.SetName("parentHandle")
 	fn.SetLinkage(llvm.InternalLinkage)
 	fn.SetUnnamedAddr(true)
-	if p.sizeLevel >= 2 {
-		fn.AddFunctionAttr(p.ctx.CreateEnumAttribute(llvm.AttributeKindID("optsize"), 0))
-	}
+	AddStandardAttributes(fn, p.config)
 
 	// TODO: debug info