1 files changed, 272 insertions, 0 deletions
diff --git a/lib/CodeGen/CGRecordLayoutBuilder.cpp b/lib/CodeGen/CGRecordLayoutBuilder.cpp
new file mode 100644
index 0000000000..6a95566247
--- /dev/null
+++ b/lib/CodeGen/CGRecordLayoutBuilder.cpp
@@ -0,0 +1,272 @@
+//===--- CGRecordLayoutBuilder.cpp - Record builder helper ------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This is a helper class used to build CGRecordLayout objects and LLVM types.
+//
+//===----------------------------------------------------------------------===//
+
+#include "CGRecordLayoutBuilder.h"
+
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Attr.h"
+#include "clang/AST/DeclCXX.h"
+#include "clang/AST/Expr.h"
+#include "clang/AST/RecordLayout.h"
+#include "CodeGenTypes.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Target/TargetData.h"
+
+
+using namespace clang;
+using namespace CodeGen;
+
+void CGRecordLayoutBuilder::Layout(const RecordDecl *D) {
+  if (const PackedAttr* PA = D->getAttr<PackedAttr>())
+    StructPacking = PA->getAlignment();
+
+  if (LayoutFields(D))
+    return;
+  
+  assert(!StructPacking && 
+         "FIXME: Were not able to lay out a struct with #pragma pack!");
+  
+  // We weren't able to layout the struct. Try again with a packed struct
+  StructPacking = 1;
+  AlignmentAsLLVMStruct = 1;
+  FieldTypes.clear();
+  FieldInfos.clear();
+  LLVMFields.clear();
+  LLVMBitFields.clear();
+  
+  LayoutFields(D);
+}
+
+void CGRecordLayoutBuilder::LayoutBitField(const FieldDecl *D,
+                                           uint64_t FieldOffset) {
+  uint64_t FieldSize = 
+    D->getBitWidth()->EvaluateAsInt(Types.getContext()).getZExtValue();
+  
+  if (FieldSize == 0)
+    return;
+
+  uint64_t NextFieldOffset = getNextFieldOffsetInBytes() * 8;
+  unsigned NumBytesToAppend;
+  
+  if (FieldOffset < NextFieldOffset) {
+    assert(BitsAvailableInLastField && "Bitfield size mismatch!");
+    assert(!FieldInfos.empty() && "Field infos can't be empty!");
+    
+    // The bitfield begins in the previous bit-field.
+    NumBytesToAppend = 
+      llvm::RoundUpToAlignment(FieldSize - BitsAvailableInLastField, 8) / 8;
+  } else {
+    assert(FieldOffset % 8 == 0 && "Field offset not aligned correctly");
+
+    // Append padding if necessary.
+    AppendBytes((FieldOffset - NextFieldOffset) / 8);
+    
+    NumBytesToAppend = 
+      llvm::RoundUpToAlignment(FieldSize, 8) / 8;
+    
+    assert(NumBytesToAppend && "No bytes to append!");
+  }
+
+  const llvm::Type *Ty = Types.ConvertTypeForMemRecursive(D->getType());
+  uint64_t TypeSizeInBits = getTypeSizeInBytes(Ty) * 8;
+  
+  LLVMFields.push_back(LLVMFieldInfo(D, FieldOffset / TypeSizeInBits));
+  LLVMBitFields.push_back(LLVMBitFieldInfo(D, FieldOffset % TypeSizeInBits, 
+                                           FieldSize));
+  
+  AppendBytes(NumBytesToAppend);
+  
+  if (!NumBytesToAppend)
+    BitsAvailableInLastField -= FieldSize;
+  else
+    BitsAvailableInLastField = NumBytesToAppend * 8 - FieldSize;
+}
+
+bool CGRecordLayoutBuilder::LayoutField(const FieldDecl *D,
+                                        uint64_t FieldOffset) {
+  unsigned FieldPacking = StructPacking;
+  
+  // FIXME: Should this override struct packing? Probably we want to
+  // take the minimum?
+  if (const PackedAttr *PA = D->getAttr<PackedAttr>())
+    FieldPacking = PA->getAlignment();
+
+  // If the field is packed, then we need a packed struct.
+  if (!StructPacking && FieldPacking)
+    return false;
+
+  if (D->isBitField()) {
+    // We must use packed structs for unnamed bit fields since they
+    // don't affect the struct alignment.
+    if (!StructPacking && !D->getDeclName())
+      return false;
+    
+    LayoutBitField(D, FieldOffset);
+    return true;
+  }
+  
+  const llvm::Type *Ty = Types.ConvertTypeForMemRecursive(D->getType());
+
+  // Check if the field is aligned.
+  if (const AlignedAttr *PA = D->getAttr<AlignedAttr>()) {
+    unsigned FieldAlign = PA->getAlignment();
+   
+    if (!StructPacking && getTypeAlignment(Ty) > FieldAlign)
+      return false;
+  }
+   
+  assert(FieldOffset % 8 == 0 && "FieldOffset is not on a byte boundary!");
+  
+  uint64_t FieldOffsetInBytes = FieldOffset / 8;
+  
+  // Append padding if necessary.
+  AppendPadding(FieldOffsetInBytes, Ty);
+  
+  uint64_t FieldSizeInBytes = getTypeSizeInBytes(Ty);
+
+  // Now append the field.
+  LLVMFields.push_back(LLVMFieldInfo(D, FieldTypes.size()));
+  AppendField(FieldOffsetInBytes, FieldSizeInBytes, Ty);
+  
+  return true;
+}
+
+bool CGRecordLayoutBuilder::LayoutFields(const RecordDecl *D) {
+  assert(!D->isUnion() && "Can't call LayoutFields on a union!");
+  
+  const ASTRecordLayout &Layout = 
+    Types.getContext().getASTRecordLayout(D);
+  
+  unsigned FieldNo = 0;
+  for (RecordDecl::field_iterator Field = D->field_begin(), 
+       FieldEnd = D->field_end(); Field != FieldEnd; ++Field, ++FieldNo) {
+    if (!LayoutField(*Field, Layout.getFieldOffset(FieldNo))) {
+      assert(!StructPacking && 
+             "Could not layout fields even with a packed LLVM struct!");
+      return false;
+    }
+  }
+
+  // Append tail padding if necessary.
+  if (Layout.getSize() / 8 > getNextFieldOffsetInBytes())
+    AppendPadding(Layout.getSize() / 8, AlignmentAsLLVMStruct);
+  
+  return true;
+}
+
+void CGRecordLayoutBuilder::AppendField(uint64_t FieldOffsetInBytes, 
+                                        uint64_t FieldSizeInBytes,
+                                        const llvm::Type *FieldTy) {
+  AlignmentAsLLVMStruct = std::max(AlignmentAsLLVMStruct,
+                                   getTypeAlignment(FieldTy));
+                                   
+  FieldTypes.push_back(FieldTy);
+  FieldInfos.push_back(FieldInfo(FieldOffsetInBytes, FieldSizeInBytes));
+
+  BitsAvailableInLastField = 0;
+}
+
+void 
+CGRecordLayoutBuilder::AppendPadding(uint64_t FieldOffsetInBytes,
+                                     const llvm::Type *FieldTy) {
+  AppendPadding(FieldOffsetInBytes, getTypeAlignment(FieldTy));
+}
+
+void CGRecordLayoutBuilder::AppendPadding(uint64_t FieldOffsetInBytes, 
+                                          unsigned FieldAlignment) {
+  uint64_t NextFieldOffsetInBytes = getNextFieldOffsetInBytes();
+  assert(NextFieldOffsetInBytes <= FieldOffsetInBytes &&
+         "Incorrect field layout!");
+  
+  // Round up the field offset to the alignment of the field type.
+  uint64_t AlignedNextFieldOffsetInBytes = 
+    llvm::RoundUpToAlignment(NextFieldOffsetInBytes, FieldAlignment);
+
+  if (AlignedNextFieldOffsetInBytes < FieldOffsetInBytes) {
+    // Even with alignment, the field offset is not at the right place,
+    // insert padding.
+    uint64_t PaddingInBytes = FieldOffsetInBytes - NextFieldOffsetInBytes;
+
+    AppendBytes(PaddingInBytes);
+  }
+}
+
+void CGRecordLayoutBuilder::AppendBytes(uint64_t NumBytes) {
+  if (NumBytes == 0)
+    return;
+  
+  const llvm::Type *Ty = llvm::Type::Int8Ty;
+  if (NumBytes > 1) {
+    // FIXME: Use a VMContext.
+    Ty = llvm::ArrayType::get(Ty, NumBytes);
+  }
+  
+  // Append the padding field
+  AppendField(getNextFieldOffsetInBytes(), NumBytes, Ty);
+}
+
+uint64_t CGRecordLayoutBuilder::getNextFieldOffsetInBytes() const {
+  if (FieldInfos.empty())
+    return 0;
+  
+  const FieldInfo &LastInfo = FieldInfos.back();
+  return LastInfo.OffsetInBytes + LastInfo.SizeInBytes;
+}
+
+unsigned CGRecordLayoutBuilder::getTypeAlignment(const llvm::Type *Ty) const {
+  if (StructPacking) {
+    assert(StructPacking == 1 && "FIXME: What if StructPacking is not 1 here");
+    return 1;
+  }
+  
+  return Types.getTargetData().getABITypeAlignment(Ty);
+}
+
+uint64_t CGRecordLayoutBuilder::getTypeSizeInBytes(const llvm::Type *Ty) const {
+  return Types.getTargetData().getTypeAllocSize(Ty);
+}
+
+CGRecordLayout *
+CGRecordLayoutBuilder::ComputeLayout(CodeGenTypes &Types,
+                                     const RecordDecl *D) {
+  CGRecordLayoutBuilder Builder(Types);
+  
+  if (D->isUnion())
+    return 0;
+
+  Builder.Layout(D);
+  
+  // FIXME: Once this works well enough, enable it.
+  return 0;
+  
+  // FIXME: Use a VMContext.
+  const llvm::Type *Ty = llvm::StructType::get(Builder.FieldTypes,
+                                               Builder.StructPacking);
+  
+  // Add all the field numbers.
+  for (unsigned i = 0, e = Builder.LLVMFields.size(); i != e; ++i) {
+    const FieldDecl *FD = Builder.LLVMFields[i].first;
+    unsigned FieldNo = Builder.LLVMFields[i].second;
+
+    Types.addFieldInfo(FD, FieldNo);
+  }
+
+  // Add bitfield info.
+  for (unsigned i = 0, e = Builder.LLVMBitFields.size(); i != e; ++i) {
+    const LLVMBitFieldInfo &Info = Builder.LLVMBitFields[i];
+    
+    Types.addBitFieldInfo(Info.FD, Info.Start, Info.Size);
+  }
+  
+  return new CGRecordLayout(Ty, llvm::SmallSet<unsigned, 8>());
+}