pkg/declextract: move const handling logic from the clang tool

Export raw info about consts from the clang tool, and let the Go part handle it.
The less logic is in the clang tool, the better. Also this will allow to remove
unused includes when we know which consts we ended up using.
The more includes we include, the higher the chances we include something
that's broken.

6 files changed, 126 insertions, 52 deletions

diff --git a/tools/syz-declextract/clangtool/declextract.cpp b/tools/syz-declextract/clangtool/declextract.cpp
index c41904d8b..4012900d6 100644
--- a/tools/syz-declextract/clangtool/declextract.cpp
+++ b/tools/syz-declextract/clangtool/declextract.cpp
@@ -113,7 +113,7 @@ private:
   template <typename T> const T* getResult(StringRef ID) const;
   FieldType extractRecord(QualType QT, const RecordType* Typ, const std::string& BackupName);
   std::string extractEnum(const EnumDecl* Decl);
-  void noteConstUse(const std::string& Name, int64_t Val, const SourceRange& Range);
+  void emitConst(const std::string& Name, int64_t Val, SourceLocation Loc);
   std::string getDeclName(const Expr* Expr);
   const ValueDecl* getValueDecl(const Expr* Expr);
   std::string getDeclFileID(const Decl* Decl);
@@ -304,7 +304,7 @@ std::string Extractor::extractEnum(const EnumDecl* Decl) {
   std::vector<std::string> Values;
   for (const auto* Enumerator : Decl->enumerators()) {
     const std::string& Name = Enumerator->getNameAsString();
-    noteConstUse(Name, Enumerator->getInitVal().getExtValue(), Decl->getSourceRange());
+    emitConst(Name, Enumerator->getInitVal().getExtValue(), Decl->getBeginLoc());
     Values.push_back(Name);
   }
   Output.emit(Enum{
@@ -314,19 +314,11 @@ std::string Extractor::extractEnum(const EnumDecl* Decl) {
   return Name;
 }
 
-void Extractor::noteConstUse(const std::string& Name, int64_t Val, const SourceRange& Range) {
-  const std::string& Filename = std::filesystem::relative(SourceManager->getFilename(Range.getBegin()).str());
-  // Include only uapi headers. Some ioctl commands defined in internal headers, or even in .c files.
-  // They have high chances of breaking compilation during const extract.
-  // If it's not defined in uapi, emit define with concrete value.
-  // Note: the value may be wrong for other arches.
-  if (Filename.find("/uapi/") != std::string::npos && Filename.back() == 'h') {
-    Output.emit(Include{Filename});
-    return;
-  }
-  Output.emit(Define{
+void Extractor::emitConst(const std::string& Name, int64_t Val, SourceLocation Loc) {
+  Output.emit(ConstInfo{
       .Name = Name,
-      .Value = std::to_string(Val),
+      .Filename = std::filesystem::relative(SourceManager->getFilename(Loc).str()),
+      .Value = Val,
   });
 }
 
@@ -445,8 +437,8 @@ std::vector<std::pair<int, std::string>> Extractor::extractDesignatedInitConsts(
   for (auto* Match : Matches) {
     const int64_t Val = *Match->getAPValueResult().getInt().getRawData();
     const auto& Name = Match->getEnumConstantDecl()->getNameAsString();
-    const auto& SR = Match->getEnumConstantDecl()->getSourceRange();
-    noteConstUse(Name, Val, SR);
+    const auto& Loc = Match->getEnumConstantDecl()->getBeginLoc();
+    emitConst(Name, Val, Loc);
     Inits.emplace_back(Val, Name);
   }
   return Inits;
@@ -523,7 +515,7 @@ void Extractor::matchNetlinkFamily() {
       if (!CmdInit)
         continue;
       const std::string& OpName = CmdInit->getNameAsString();
-      noteConstUse(OpName, CmdInit->getInitVal().getExtValue(), CmdInit->getSourceRange());
+      emitConst(OpName, CmdInit->getInitVal().getExtValue(), CmdInit->getBeginLoc());
       std::string Policy;
       if (OpsFields.count("policy") != 0) {
         if (const auto* PolicyDecl = OpInit->getInit(OpsFields["policy"])->getAsBuiltinConstantDeclRef(*Context))
@@ -818,7 +810,7 @@ std::vector<IoctlCmd> Extractor::extractIoctlCommands(const std::string& Ioctl)
     if (MacroDef == Macros.end())
       continue;
     int64_t CmdVal = evaluate(Cmd);
-    noteConstUse(CmdStr, CmdVal, MacroDef->second.SourceRange);
+    emitConst(CmdStr, CmdVal, MacroDef->second.SourceRange.getBegin());
     FieldType CmdType;
     const auto Dir = _IOC_DIR(CmdVal);
     if (Dir == _IOC_NONE) {
diff --git a/tools/syz-declextract/clangtool/output.h b/tools/syz-declextract/clangtool/output.h
index 24ab82f61..d89d64afb 100644
--- a/tools/syz-declextract/clangtool/output.h
+++ b/tools/syz-declextract/clangtool/output.h
@@ -62,13 +62,10 @@ struct BufferType {
   bool IsNonTerminated = false;
 };
 
-struct Include {
-  std::string Filename;
-};
-
-struct Define {
+struct ConstInfo {
   std::string Name;
-  std::string Value;
+  std::string Filename;
+  int64_t Value;
 };
 
 struct Field {
@@ -201,9 +198,10 @@ struct NetlinkPolicy {
   std::vector<NetlinkAttr> Attrs;
 };
 
-inline void print(JSONPrinter& Printer, const Define& V) {
+inline void print(JSONPrinter& Printer, const ConstInfo& V) {
   JSONPrinter::Scope Scope(Printer);
   Printer.Field("name", V.Name);
+  Printer.Field("filename", V.Filename);
   Printer.Field("value", V.Value, true);
 }
 
@@ -412,13 +410,8 @@ inline FieldType TodoType() {
 
 class Output {
 public:
-  void emit(Include&& Inc) {
-    if (IncludesDedup.insert(Inc.Filename).second)
-      Includes.push_back(Inc.Filename);
-  }
-
   void emit(Function&& V) { Functions.push_back(std::move(V)); }
-  void emit(Define&& V) { Defines.push_back(std::move(V)); }
+  void emit(ConstInfo&& V) { Consts.push_back(std::move(V)); }
   void emit(Struct&& V) { Structs.push_back(std::move(V)); }
   void emit(Enum&& V) { Enums.push_back(std::move(V)); }
   void emit(Syscall&& V) { Syscalls.push_back(std::move(V)); }
@@ -430,8 +423,7 @@ public:
   void print() const {
     JSONPrinter Printer;
     Printer.Field("functions", Functions);
-    Printer.Field("includes", Includes);
-    Printer.Field("defines", Defines);
+    Printer.Field("consts", Consts);
     Printer.Field("enums", Enums);
     Printer.Field("structs", Structs);
     Printer.Field("syscalls", Syscalls);
@@ -443,9 +435,7 @@ public:
 
 private:
   std::vector<Function> Functions;
-  std::vector<std::string> Includes;
-  std::unordered_set<std::string> IncludesDedup;
-  std::vector<Define> Defines;
+  std::vector<ConstInfo> Consts;
   std::vector<Enum> Enums;
   std::vector<Struct> Structs;
   std::vector<Syscall> Syscalls;
diff --git a/tools/syz-declextract/testdata/file_operations.c.json b/tools/syz-declextract/testdata/file_operations.c.json
index 94ad7bef5..df1c9a20f 100644
--- a/tools/syz-declextract/testdata/file_operations.c.json
+++ b/tools/syz-declextract/testdata/file_operations.c.json
@@ -47,8 +47,32 @@
 			"is_static": true
 		}
 	],
-	"includes": [
-		"include/uapi/file_operations.h"
+	"consts": [
+		{
+			"name": "FOO_IOCTL1",
+			"filename": "include/uapi/file_operations.h",
+			"value": 25345
+		},
+		{
+			"name": "FOO_IOCTL2",
+			"filename": "include/uapi/file_operations.h",
+			"value": 2147771138
+		},
+		{
+			"name": "FOO_IOCTL3",
+			"filename": "include/uapi/file_operations.h",
+			"value": 2148033283
+		},
+		{
+			"name": "FOO_IOCTL4",
+			"filename": "include/uapi/file_operations.h",
+			"value": 1074291460
+		},
+		{
+			"name": "FOO_IOCTL5",
+			"filename": "include/uapi/file_operations.h",
+			"value": 3221775109
+		}
 	],
 	"structs": [
 		{
diff --git a/tools/syz-declextract/testdata/io_uring.c.json b/tools/syz-declextract/testdata/io_uring.c.json
index 3f0a74a95..da91ce1b6 100644
--- a/tools/syz-declextract/testdata/io_uring.c.json
+++ b/tools/syz-declextract/testdata/io_uring.c.json
@@ -29,8 +29,27 @@
 			"file": "io_uring.c"
 		}
 	],
-	"includes": [
-		"include/uapi/io_uring.h"
+	"consts": [
+		{
+			"name": "IORING_OP_NOP",
+			"filename": "include/uapi/io_uring.h",
+			"value": 0
+		},
+		{
+			"name": "IORING_OP_NOT_SUPPORTED",
+			"filename": "include/uapi/io_uring.h",
+			"value": 3
+		},
+		{
+			"name": "IORING_OP_READV",
+			"filename": "include/uapi/io_uring.h",
+			"value": 1
+		},
+		{
+			"name": "IORING_OP_WRITEV",
+			"filename": "include/uapi/io_uring.h",
+			"value": 2
+		}
 	],
 	"iouring_ops": [
 		{
diff --git a/tools/syz-declextract/testdata/netlink.c.json b/tools/syz-declextract/testdata/netlink.c.json
index 4233eab7d..e1c2754b1 100644
--- a/tools/syz-declextract/testdata/netlink.c.json
+++ b/tools/syz-declextract/testdata/netlink.c.json
@@ -37,25 +37,71 @@
 			"is_static": true
 		}
 	],
-	"includes": [
-		"include/uapi/netlink_family.h"
-	],
-	"defines": [
+	"consts": [
 		{
 			"name": "NETLINK_BAR_CMD_FOO",
-			"value": "0"
+			"filename": "netlink.c",
+			"value": 0
+		},
+		{
+			"name": "NETLINK_FOO_ATTR1",
+			"filename": "include/uapi/netlink_family.h",
+			"value": 0
+		},
+		{
+			"name": "NETLINK_FOO_ATTR2",
+			"filename": "include/uapi/netlink_family.h",
+			"value": 1
+		},
+		{
+			"name": "NETLINK_FOO_ATTR3",
+			"filename": "include/uapi/netlink_family.h",
+			"value": 4
+		},
+		{
+			"name": "NETLINK_FOO_ATTR4",
+			"filename": "include/uapi/netlink_family.h",
+			"value": 5
+		},
+		{
+			"name": "NETLINK_FOO_ATTR5",
+			"filename": "include/uapi/netlink_family.h",
+			"value": 6
+		},
+		{
+			"name": "NETLINK_FOO_ATTR6",
+			"filename": "include/uapi/netlink_family.h",
+			"value": 7
+		},
+		{
+			"name": "NETLINK_FOO_ATTR7",
+			"filename": "include/uapi/netlink_family.h",
+			"value": 8
+		},
+		{
+			"name": "NETLINK_FOO_CMD_BAR",
+			"filename": "include/uapi/netlink_family.h",
+			"value": 1
+		},
+		{
+			"name": "NETLINK_FOO_CMD_FOO",
+			"filename": "include/uapi/netlink_family.h",
+			"value": 0
 		},
 		{
 			"name": "NETLINK_FOO_NESTED_ATTR1",
-			"value": "0"
+			"filename": "netlink.c",
+			"value": 0
 		},
 		{
 			"name": "NETLINK_FOO_NESTED_ATTR2",
-			"value": "1"
+			"filename": "netlink.c",
+			"value": 1
 		},
 		{
 			"name": "NETLINK_NOPOLICY_CMD",
-			"value": "0"
+			"filename": "netlink.c",
+			"value": 0
 		}
 	],
 	"structs": [
diff --git a/tools/syz-declextract/testdata/types.c.json b/tools/syz-declextract/testdata/types.c.json
index a5a7088db..82d45e3fe 100644
--- a/tools/syz-declextract/testdata/types.c.json
+++ b/tools/syz-declextract/testdata/types.c.json
@@ -111,18 +111,21 @@
 			]
 		}
 	],
-	"defines": [
+	"consts": [
 		{
 			"name": "a",
-			"value": "0"
+			"filename": "types.c",
+			"value": 0
 		},
 		{
 			"name": "b",
-			"value": "1"
+			"filename": "types.c",
+			"value": 1
 		},
 		{
 			"name": "c",
-			"value": "2"
+			"filename": "types.c",
+			"value": 2
 		}
 	],
 	"enums": [