SILGen: ban getSILArgumentConvention

This function will give the wrong convention in SILGen when
using -enable-sil-opaque-values. In particular, it will say
arguments are indirect when they are not.

include/swift/SIL/SILFunctionConventions.h

@@ -31,6 +31,7 @@
 #define SWIFT_SIL_FUNCTIONCONVENTIONS_H
 
 #include "swift/AST/Types.h"
+#include "swift/Basic/AccessControls.h"
 #include "swift/SIL/SILArgumentConvention.h"
 #include "swift/SIL/SILType.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -526,11 +527,9 @@ public:
                                          - getNumIndirectSILErrorResults()];
   }
 
-  /// WARNING: Do not use this from SILGen!
-  /// Use methods such as `isSILIndirect` or query the ParameterInfo instead.
-  ///
   /// Return the SIL argument convention of apply/entry argument at
   /// the given argument index.
+  SWIFT_UNAVAILABLE_IN_SILGEN_MSG("Use methods such as `isSILIndirect` or query the ParameterInfo instead.")
   SILArgumentConvention getSILArgumentConvention(unsigned index) const;
 
   /// Return the SIL type of the apply/entry argument at the given index.

include/swift/SIL/SILGenUtils.h

@@ -0,0 +1,17 @@
+//
+// Created by Kavon Farvardin on 11/19/25.
+//
+
+#ifndef SWIFT_SILGENUTILS_H
+#define SWIFT_SILGENUTILS_H
+
+#include "swift/SIL/SILValue.h"
+
+namespace swift {
+
+// Unsafe access may have invalid storage (e.g. a RawPointer).
+bool isPossibleUnsafeAccessInvalidStorage(SILValue access, SILFunction *F);
+
+} // namespace swift
+
+#endif // SWIFT_SILGENUTILS_H

lib/SIL/IR/SILArgument.cpp

@@ -87,8 +87,6 @@ SILParameterInfo SILFunctionArgument::getKnownParameterInfo() const {
   return getFunction()->getConventions().getParamInfoForSILArg(getIndex());
 }
 
-/// WARNING: Do not use this from SILGen!
-/// Use methods such as `isSILIndirect` or query the ParameterInfo instead.
 SILArgumentConvention
 SILFunctionConventions::getSILArgumentConvention(unsigned index) const {
   assert(index < getNumSILArguments());

lib/SIL/Utils/MemAccessUtils.cpp

@@ -22,6 +22,7 @@
 #include "swift/SIL/SILBridging.h"
 #include "swift/SIL/SILInstruction.h"
 #include "swift/SIL/SILModule.h"
+#include "swift/SIL/SILGenUtils.h"
 #include "swift/SIL/SILUndef.h"
 #include "swift/SIL/Test.h"
 #include "llvm/Support/Debug.h"
@@ -2485,6 +2486,12 @@ void swift::checkSwitchEnumBlockArg(SILPhiArgument *arg) {
   }
 }
 
+bool swift::isPossibleUnsafeAccessInvalidStorage(SILValue address,
+                                                 SILFunction *F) {
+  auto storage = AccessStorage::compute(address);
+  return storage && !isPossibleFormalAccessStorage(storage, F);
+}
+
 bool swift::isPossibleFormalAccessStorage(const AccessStorage &storage,
                                           SILFunction *F) {
   switch (storage.getKind()) {

lib/SILGen/Cleanup.h

@@ -17,6 +17,8 @@
 #ifndef SWIFT_SILGEN_CLEANUP_H
 #define SWIFT_SILGEN_CLEANUP_H
 
+#define SWIFT_INCLUDED_IN_SILGEN_SOURCES
+
 #include "swift/Basic/Assertions.h"
 #include "swift/Basic/Debug.h"
 #include "swift/Basic/DiverseStack.h"

lib/SILGen/ManagedValue.h

@@ -20,6 +20,8 @@
 #ifndef SWIFT_LOWERING_MANAGEDVALUE_H
 #define SWIFT_LOWERING_MANAGEDVALUE_H
 
+#define SWIFT_INCLUDED_IN_SILGEN_SOURCES
+
 #include "Cleanup.h"
 #include "llvm/ADT/PointerIntPair.h"
 #include "swift/Basic/Assertions.h"

lib/SILGen/SILGen.h

@@ -13,6 +13,8 @@
 #ifndef SILGEN_H
 #define SILGEN_H
 
+#define SWIFT_INCLUDED_IN_SILGEN_SOURCES
+
 #include "ASTVisitor.h"
 #include "Cleanup.h"
 #include "swift/AST/ASTContext.h"

lib/SILGen/SILGenLValue.cpp

@@ -35,7 +35,7 @@
 #include "swift/Basic/Assertions.h"
 #include "swift/SIL/Consumption.h"
 #include "swift/SIL/InstructionUtils.h"
-#include "swift/SIL/MemAccessUtils.h"
+#include "swift/SIL/SILGenUtils.h"
 #include "swift/SIL/PrettyStackTrace.h"
 #include "swift/SIL/SILArgument.h"
 #include "swift/SIL/SILInstruction.h"
@@ -708,9 +708,7 @@ SILValue UnenforcedAccess::beginAccess(SILGenFunction &SGF, SILLocation loc,
   if (!SGF.getOptions().VerifyExclusivity)
     return address;
 
-  auto storage = AccessStorage::compute(address);
-  // Unsafe access may have invalid storage (e.g. a RawPointer).
-  if (storage && !isPossibleFormalAccessStorage(storage, &SGF.F))
+  if (isPossibleUnsafeAccessInvalidStorage(address, &SGF.F))
     return address;
 
   auto BAI =