refactor(codegen): share the READ-mode check of file read and EOF helpers

__cps_file_read and __cps_file_eof both emitted the same mode load,
comparison and ErrNotRead check after the slot lookup; emit it through
FileHandler::emitRequireReadMode instead.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

2 files changed, 11 insertions, 8 deletions

diff --git a/lib/CodeGen/FileHandler.cc b/lib/CodeGen/FileHandler.cc
index a2c3492..b471aa5 100644
--- a/lib/CodeGen/FileHandler.cc
+++ b/lib/CodeGen/FileHandler.cc
@@ -121,6 +121,14 @@ Value *FileHandler::emitLookupOrFail(Value *Name, Value *Line) {
     return Idx;
 }
 
+// Report and throw unless the open file in slot Idx was opened for READ.
+void FileHandler::emitRequireReadMode(Value *Idx, Value *Name, Value *Line) {
+    Type *I8 = Type::getInt8Ty(Context);
+    Value *Mode = Builder.CreateLoad(I8, emitSlotGEP(FileModes, I8, Idx), "mode");
+    Value *NotRead = Builder.CreateICmpNE(Mode, ConstantInt::get(I8, uint8_t(FileMode::Read)), "not_read");
+    Checker.emitCheck(NotRead, ErrNotRead, {Line, Name});
+}
+
 // i64 __cps_file_find(ptr name): strcmp scan over occupied slots; -1 on miss.
 void FileHandler::buildFindFn() {
     PointerType *PtrTy = PointerType::getUnqual(Context);
diff --git a/lib/CodeGen/FileRuntimeIO.cc b/lib/CodeGen/FileRuntimeIO.cc
index c23515d..c899528 100644
--- a/lib/CodeGen/FileRuntimeIO.cc
+++ b/lib/CodeGen/FileRuntimeIO.cc
@@ -25,9 +25,7 @@ void FileHandler::buildReadFn() {
     Line->setName("line");
 
     Value *Idx = emitLookupOrFail(Name, Line);
-    Value *Mode = Builder.CreateLoad(I8, emitSlotGEP(FileModes, I8, Idx), "mode");
-    Value *NotRead = Builder.CreateICmpNE(Mode, ConstantInt::get(I8, uint8_t(FileMode::Read)), "not_read");
-    Checker.emitCheck(NotRead, ErrNotRead, {Line, Name});
+    emitRequireReadMode(Idx, Name, Line);
     Value *Handle = Builder.CreateLoad(PtrTy, emitSlotGEP(FileHandles, PtrTy, Idx), "handle");
 
     Value *MinusOne = ConstantInt::get(Context, APInt(32, -1, /*isSigned=*/true));
@@ -166,9 +164,8 @@ void FileHandler::buildCloseFn() {
 void FileHandler::buildEofFn() {
     PointerType *PtrTy = PointerType::getUnqual(Context);
     Type *I32 = Type::getInt32Ty(Context);
-    Type *I8 = Type::getInt8Ty(Context);
 
-    EofFn = createHelper("__cps_file_eof",
+    EofFn =createHelper("__cps_file_eof",
                          FunctionType::get(Type::getInt1Ty(Context), {PtrTy, I32}, false));
     Value *Name = EofFn->getArg(0);
     Value *Line = EofFn->getArg(1);
@@ -176,9 +173,7 @@ void FileHandler::buildEofFn() {
     Line->setName("line");
 
     Value *Idx = emitLookupOrFail(Name, Line);
-    Value *Mode = Builder.CreateLoad(I8, emitSlotGEP(FileModes, I8, Idx), "mode");
-    Value *NotRead = Builder.CreateICmpNE(Mode, ConstantInt::get(I8, uint8_t(FileMode::Read)), "not_read");
-    Checker.emitCheck(NotRead, ErrNotRead, {Line, Name});
+    emitRequireReadMode(Idx, Name, Line);
 
     Value *Handle = Builder.CreateLoad(PtrTy, emitSlotGEP(FileHandles, PtrTy, Idx), "handle");
     Value *Ch = Builder.CreateCall(FgetcFunc, {Handle}, "c");