pkg/declextract: remove unused includes and defines

This is nice on its own, but this will also help to prevent
lots of problems when we export more info from the clang tool in future.
The clang tool does not know what will end up in the final descriptions,
so it exports info about all consts that it encounters.
As the result we pull in lots of includes/defines, and lots of kernel
includes/defines are broken or create problems.
So the fewer we have, the better.

1 files changed, 9 insertions, 4 deletions

diff --git a/pkg/compiler/consts.go b/pkg/compiler/consts.go
index bcbd40e52..6ce3f81f1 100644
--- a/pkg/compiler/consts.go
+++ b/pkg/compiler/consts.go
@@ -23,6 +23,7 @@ type ConstInfo struct {
 type Const struct {
 	Name string
 	Pos  ast.Pos
+	Used bool // otherwise only defined
 }
 
 func ExtractConsts(desc *ast.Description, target *targets.Target, eh ast.ErrorHandler) map[string]*ConstInfo {
@@ -86,7 +87,7 @@ func (comp *compiler) extractConsts() map[string]*ConstInfo {
 				comp.error(pos, "redefining builtin const %v", name)
 			}
 			info.defines[name] = v
-			comp.addConst(ctx, pos, name)
+			ctx.addConst(pos, name, false)
 		case *ast.Call:
 			if comp.target.HasCallNumber(n.CallName) {
 				comp.addConst(ctx, pos, comp.target.SyscallPrefix+n.CallName)
@@ -178,10 +179,10 @@ func (comp *compiler) addConst(ctx *constContext, pos ast.Pos, name string) {
 	if _, isFlag := comp.intFlags[name]; isFlag {
 		return
 	}
-	ctx.addConst(pos, name)
+	ctx.addConst(pos, name, true)
 	for _, instantions := range ctx.instantionStack {
 		for _, pos1 := range instantions {
-			ctx.addConst(pos1, name)
+			ctx.addConst(pos1, name, true)
 		}
 	}
 }
@@ -193,11 +194,15 @@ type constInfo struct {
 	incdirArray  []string
 }
 
-func (ctx *constContext) addConst(pos ast.Pos, name string) {
+func (ctx *constContext) addConst(pos ast.Pos, name string, used bool) {
 	info := ctx.getConstInfo(pos)
+	if c := info.consts[name]; c != nil && c.Used {
+		used = true
+	}
 	info.consts[name] = &Const{
 		Pos:  pos,
 		Name: name,
+		Used: used,
 	}
 }