[PATCH] D115320: Avoid setting tbaa information on return type of call to inline assember

[Sindhu Chittireddy via Phabricator via cfe-commits]

schittir created this revision.
Herald added subscribers: jeroen.dobbelaere, kosarev.
schittir requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

In 32bit mode, attaching TBAA metadata to the store following the call to 
inline assembler results in describing the wrong type by making a fake 
lvalue(i.e., whatever the inline assembler happens to leave in EAX:EDX.) Even 
if inline assembler somehow describes the correct type, setting TBAA 
information on return type of call to inline assembler is likely not correct, 
since TBAA rules need not apply to inline assembler.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D115320

Files:
  clang/lib/CodeGen/CGStmt.cpp
  clang/lib/CodeGen/CodeGenFunction.h
  clang/lib/CodeGen/CodeGenModule.cpp
  clang/lib/CodeGen/CodeGenModule.h


Index: clang/lib/CodeGen/CodeGenModule.h
===================================================================
--- clang/lib/CodeGen/CodeGenModule.h
+++ clang/lib/CodeGen/CodeGenModule.h
@@ -746,6 +746,9 @@
   /// an object of the given type.
   TBAAAccessInfo getTBAAAccessInfo(QualType AccessType);
 
+  /// returnNullTBAA - Return empty TBAA constructor
+  TBAAAccessInfo returnNullTBAA();
+
   /// getTBAAVTablePtrAccessInfo - Get the TBAA information that describes an
   /// access to a virtual table pointer.
   TBAAAccessInfo getTBAAVTablePtrAccessInfo(llvm::Type *VTablePtrType);
Index: clang/lib/CodeGen/CodeGenModule.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenModule.cpp
+++ clang/lib/CodeGen/CodeGenModule.cpp
@@ -935,6 +935,10 @@
   return TBAA->getAccessInfo(AccessType);
 }
 
+TBAAAccessInfo CodeGenModule::returnNullTBAA() {
+  return TBAAAccessInfo();
+}
+
 TBAAAccessInfo
 CodeGenModule::getTBAAVTablePtrAccessInfo(llvm::Type *VTablePtrType) {
   if (!TBAA)
Index: clang/lib/CodeGen/CodeGenFunction.h
===================================================================
--- clang/lib/CodeGen/CodeGenFunction.h
+++ clang/lib/CodeGen/CodeGenFunction.h
@@ -2504,6 +2504,12 @@
                             BaseInfo, TBAAInfo);
   }
 
+  LValue MakeAddrLValueWithoutTBAA(Address Addr, QualType T,
+                        AlignmentSource Source = AlignmentSource::Type) {
+    return LValue::MakeAddr(Addr, T, getContext(), LValueBaseInfo(Source),
+                            CGM.returnNullTBAA());
+  }
+
   LValue MakeNaturalAlignPointeeAddrLValue(llvm::Value *V, QualType T);
   LValue MakeNaturalAlignAddrLValue(llvm::Value *V, QualType T);
 
Index: clang/lib/CodeGen/CGStmt.cpp
===================================================================
--- clang/lib/CodeGen/CGStmt.cpp
+++ clang/lib/CodeGen/CGStmt.cpp
@@ -2454,7 +2454,7 @@
     const ABIArgInfo &RetAI = CurFnInfo->getReturnInfo();
     if (RetAI.isDirect() || RetAI.isExtend()) {
       // Make a fake lvalue for the return value slot.
-      LValue ReturnSlot = MakeAddrLValue(ReturnValue, FnRetTy);
+      LValue ReturnSlot = MakeAddrLValueWithoutTBAA(ReturnValue, FnRetTy);
       CGM.getTargetCodeGenInfo().addReturnRegisterOutputs(
           *this, ReturnSlot, Constraints, ResultRegTypes, ResultTruncRegTypes,
           ResultRegDests, AsmString, S.getNumOutputs());



Index: clang/lib/CodeGen/CodeGenModule.h
===================================================================
--- clang/lib/CodeGen/CodeGenModule.h
+++ clang/lib/CodeGen/CodeGenModule.h
@@ -746,6 +746,9 @@
   /// an object of the given type.
   TBAAAccessInfo getTBAAAccessInfo(QualType AccessType);
 
+  /// returnNullTBAA - Return empty TBAA constructor
+  TBAAAccessInfo returnNullTBAA();
+
   /// getTBAAVTablePtrAccessInfo - Get the TBAA information that describes an
   /// access to a virtual table pointer.
   TBAAAccessInfo getTBAAVTablePtrAccessInfo(llvm::Type *VTablePtrType);
Index: clang/lib/CodeGen/CodeGenModule.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenModule.cpp
+++ clang/lib/CodeGen/CodeGenModule.cpp
@@ -935,6 +935,10 @@
   return TBAA->getAccessInfo(AccessType);
 }
 
+TBAAAccessInfo CodeGenModule::returnNullTBAA() {
+  return TBAAAccessInfo();
+}
+
 TBAAAccessInfo
 CodeGenModule::getTBAAVTablePtrAccessInfo(llvm::Type *VTablePtrType) {
   if (!TBAA)
Index: clang/lib/CodeGen/CodeGenFunction.h
===================================================================
--- clang/lib/CodeGen/CodeGenFunction.h
+++ clang/lib/CodeGen/CodeGenFunction.h
@@ -2504,6 +2504,12 @@
                             BaseInfo, TBAAInfo);
   }
 
+  LValue MakeAddrLValueWithoutTBAA(Address Addr, QualType T,
+                        AlignmentSource Source = AlignmentSource::Type) {
+    return LValue::MakeAddr(Addr, T, getContext(), LValueBaseInfo(Source),
+                            CGM.returnNullTBAA());
+  }
+
   LValue MakeNaturalAlignPointeeAddrLValue(llvm::Value *V, QualType T);
   LValue MakeNaturalAlignAddrLValue(llvm::Value *V, QualType T);
 
Index: clang/lib/CodeGen/CGStmt.cpp
===================================================================
--- clang/lib/CodeGen/CGStmt.cpp
+++ clang/lib/CodeGen/CGStmt.cpp
@@ -2454,7 +2454,7 @@
     const ABIArgInfo &RetAI = CurFnInfo->getReturnInfo();
     if (RetAI.isDirect() || RetAI.isExtend()) {
       // Make a fake lvalue for the return value slot.
-      LValue ReturnSlot = MakeAddrLValue(ReturnValue, FnRetTy);
+      LValue ReturnSlot = MakeAddrLValueWithoutTBAA(ReturnValue, FnRetTy);
       CGM.getTargetCodeGenInfo().addReturnRegisterOutputs(
           *this, ReturnSlot, Constraints, ResultRegTypes, ResultTruncRegTypes,
           ResultRegDests, AsmString, S.getNumOutputs());

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