Revert "[BPF] Preserve debuginfo array/union/struct type/access index"

This reverts commit r365435.

Forgot adding the Differential Revision link. Will add to the
commit message and resubmit.

llvm-svn: 365436

Author: yonghong-song

clang/docs/LanguageExtensions.rst

@@ -1950,35 +1950,6 @@ form of ``__builtin_operator_delete`` is currently available.
 These builtins are intended for use in the implementation of ``std::allocator``
 and other similar allocation libraries, and are only available in C++.
 
-``__builtin_preserve_access_index``
------------------------------------
-
-``__builtin_preserve_access_index`` specifies a code section where
-array subscript access and structure/union member access are relocatable
-under bpf compile-once run-everywhere framework. Debuginfo (typically
-with ``-g``) is needed, otherwise, the compiler will exit with an error.
-
-**Syntax**:
-
-.. code-block:: c
-
-  const void * __builtin_preserve_access_index(const void * ptr)
-
-**Example of Use**:
-
-.. code-block:: c
-
-  struct t {
-    int i;
-    int j;
-    union {
-      int a;
-      int b;
-    } c[4];
-  };
-  struct t *v = ...;
-  const void *pb =__builtin_preserve_access_index(&v->c[3].b);
-
 Multiprecision Arithmetic Builtins
 ----------------------------------
 

clang/include/clang/Basic/Builtins.def

@@ -1449,7 +1449,6 @@ BUILTIN(__builtin_operator_new, "v*z", "tc")
 BUILTIN(__builtin_operator_delete, "vv*", "tn")
 BUILTIN(__builtin_char_memchr, "c*cC*iz", "n")
 BUILTIN(__builtin_dump_struct, "ivC*v*", "tn")
-BUILTIN(__builtin_preserve_access_index, "vC*vC*", "nU")
 
 // Safestack builtins
 BUILTIN(__builtin___get_unsafe_stack_start, "v*", "Fn")

clang/lib/CodeGen/CGBuilder.h

@@ -298,21 +298,6 @@ class CGBuilderTy : public CGBuilderBaseTy {
     return CreateMemSet(Dest.getPointer(), Value, Size,
                         Dest.getAlignment().getQuantity(), IsVolatile);
   }
-
-  using CGBuilderBaseTy::CreatePreserveStructAccessIndex;
-  Address CreatePreserveStructAccessIndex(Address Addr,
-                                          unsigned Index,
-                                          unsigned FieldIndex,
-                                          llvm::MDNode *DbgInfo) {
-    llvm::StructType *ElTy = cast<llvm::StructType>(Addr.getElementType());
-    const llvm::DataLayout &DL = BB->getParent()->getParent()->getDataLayout();
-    const llvm::StructLayout *Layout = DL.getStructLayout(ElTy);
-    auto Offset = CharUnits::fromQuantity(Layout->getElementOffset(Index));
-
-    return Address(CreatePreserveStructAccessIndex(Addr.getPointer(),
-                                                   Index, FieldIndex, DbgInfo),
-                   Addr.getAlignment().alignmentAtOffset(Offset));
-  }
 };
 
 }  // end namespace CodeGen

clang/lib/CodeGen/CGBuiltin.cpp

@@ -1840,27 +1840,6 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
     return RValue::get(Res);
   }
 
-  case Builtin::BI__builtin_preserve_access_index: {
-    // Only enabled preserved access index region when debuginfo
-    // is available as debuginfo is needed to preserve user-level
-    // access pattern.
-    if (!getDebugInfo()) {
-      CGM.Error(E->getExprLoc(), "using builtin_preserve_access_index() without -g");
-      return RValue::get(EmitScalarExpr(E->getArg(0)));
-    }
-
-    // Nested builtin_preserve_access_index() not supported
-    if (IsInPreservedAIRegion) {
-      CGM.Error(E->getExprLoc(), "nested builtin_preserve_access_index() not supported");
-      return RValue::get(EmitScalarExpr(E->getArg(0)));
-    }
-
-    IsInPreservedAIRegion = true;
-    Value *Res = EmitScalarExpr(E->getArg(0));
-    IsInPreservedAIRegion = false;
-    return RValue::get(Res);
-  }
-
   case Builtin::BI__builtin_cimag:
   case Builtin::BI__builtin_cimagf:
   case Builtin::BI__builtin_cimagl:

clang/lib/CodeGen/CGExpr.cpp

@@ -25,7 +25,6 @@
 #include "clang/AST/Attr.h"
 #include "clang/AST/DeclObjC.h"
 #include "clang/AST/NSAPI.h"
-#include "clang/Basic/Builtins.h"
 #include "clang/Basic/CodeGenOptions.h"
 #include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/StringExtras.h"
@@ -3419,20 +3418,8 @@ static Address emitArraySubscriptGEP(CodeGenFunction &CGF, Address addr,
   CharUnits eltAlign =
     getArrayElementAlign(addr.getAlignment(), indices.back(), eltSize);
 
-  llvm::Value *eltPtr;
-  auto LastIndex = dyn_cast<llvm::ConstantInt>(indices.back());
-  if (!CGF.IsInPreservedAIRegion || !LastIndex) {
-    eltPtr = emitArraySubscriptGEP(
-        CGF, addr.getPointer(), indices, inbounds, signedIndices,
-        loc, name);
-  } else {
-    // Remember the original array subscript for bpf target
-    unsigned idx = LastIndex->getZExtValue();
-    eltPtr = CGF.Builder.CreatePreserveArrayAccessIndex(addr.getPointer(),
-                                                        indices.size() - 1,
-                                                        idx);
-  }
-
+  llvm::Value *eltPtr = emitArraySubscriptGEP(
+      CGF, addr.getPointer(), indices, inbounds, signedIndices, loc, name);
   return Address(eltPtr, eltAlign);
 }
 
@@ -3921,19 +3908,6 @@ static Address emitAddrOfFieldStorage(CodeGenFunction &CGF, Address base,
   return CGF.Builder.CreateStructGEP(base, idx, field->getName());
 }
 
-static Address emitPreserveStructAccess(CodeGenFunction &CGF, Address base,
-                                        const FieldDecl *field) {
-  const RecordDecl *rec = field->getParent();
-  llvm::DIType *DbgInfo = CGF.getDebugInfo()->getOrCreateRecordType(
-      CGF.getContext().getRecordType(rec), rec->getLocation());
-
-  unsigned idx =
-      CGF.CGM.getTypes().getCGRecordLayout(rec).getLLVMFieldNo(field);
-
-  return CGF.Builder.CreatePreserveStructAccessIndex(
-      base, idx, field->getFieldIndex(), DbgInfo);
-}
-
 static bool hasAnyVptr(const QualType Type, const ASTContext &Context) {
   const auto *RD = Type.getTypePtr()->getAsCXXRecordDecl();
   if (!RD)
@@ -4041,24 +4015,9 @@ LValue CodeGenFunction::EmitLValueForField(LValue base,
       // a barrier every time CXXRecord field with vptr is referenced.
       addr = Address(Builder.CreateLaunderInvariantGroup(addr.getPointer()),
                      addr.getAlignment());
-
-    if (IsInPreservedAIRegion) {
-      // Remember the original union field index
-      llvm::DIType *DbgInfo = getDebugInfo()->getOrCreateRecordType(
-          getContext().getRecordType(rec), rec->getLocation());
-      addr = Address(
-          Builder.CreatePreserveUnionAccessIndex(
-              addr.getPointer(), field->getFieldIndex(), DbgInfo),
-          addr.getAlignment());
-    }
   } else {
-
-    if (!IsInPreservedAIRegion)
-      // For structs, we GEP to the field that the record layout suggests.
-      addr = emitAddrOfFieldStorage(*this, addr, field);
-    else
-      // Remember the original struct field index
-      addr = emitPreserveStructAccess(*this, addr, field);
+    // For structs, we GEP to the field that the record layout suggests.
+    addr = emitAddrOfFieldStorage(*this, addr, field);
 
     // If this is a reference field, load the reference right now.
     if (FieldType->isReferenceType()) {

clang/lib/CodeGen/CodeGenFunction.h

@@ -480,10 +480,6 @@ class CodeGenFunction : public CodeGenTypeCache {
   /// finally block or filter expression.
   bool IsOutlinedSEHHelper = false;
 
-  /// True if CodeGen currently emits code inside presereved access index
-  /// region.
-  bool IsInPreservedAIRegion = false;
-
   const CodeGen::CGBlockInfo *BlockInfo = nullptr;
   llvm::Value *BlockPointer = nullptr;
 

clang/lib/Sema/SemaChecking.cpp

@@ -191,16 +191,6 @@ static bool SemaBuiltinAddressof(Sema &S, CallExpr *TheCall) {
   return false;
 }
 
-/// Check the number of arguments, and set the result type to
-/// the argument type.
-static bool SemaBuiltinPreserveAI(Sema &S, CallExpr *TheCall) {
-  if (checkArgCount(S, TheCall, 1))
-    return true;
-
-  TheCall->setType(TheCall->getArg(0)->getType());
-  return false;
-}
-
 static bool SemaBuiltinOverflow(Sema &S, CallExpr *TheCall) {
   if (checkArgCount(S, TheCall, 3))
     return true;
@@ -1419,10 +1409,6 @@ Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID,
     TheCall->setType(Context.IntTy);
     break;
   }
-  case Builtin::BI__builtin_preserve_access_index:
-    if (SemaBuiltinPreserveAI(*this, TheCall))
-      return ExprError();
-    break;
   case Builtin::BI__builtin_call_with_static_chain:
     if (SemaBuiltinCallWithStaticChain(*this, TheCall))
       return ExprError();