The third operand of a COMPONENT_REF represents the byte offset of
the field; it is accessed using component_ref_field_offset. Most of
the time you can get away with extracting the offset from the type,
using DECL_FIELD_OFFSET, which is what is done currently, but this
can fail if DECL_FIELD_OFFSET contains a PLACEHOLDER_EXPR for example.
The NON_LVALUE_EXPR Ada testcase also tests this one.
Index: gcc.llvm.master/gcc/llvm-convert.cpp
===================================================================
--- gcc.llvm.master.orig/gcc/llvm-convert.cpp 2007-03-02 15:19:49.000000000 +0100
+++ gcc.llvm.master/gcc/llvm-convert.cpp 2007-03-02 15:19:51.000000000 +0100
@@ -4588,6 +4588,20 @@
return Result;
}
+/// getComponentRefOffsetInBits - Return the offset (in bits) of the field
+/// referenced in a COMPONENT_REF exp.
+static unsigned getComponentRefOffsetInBits(tree exp) {
+ assert(TREE_CODE(exp) == COMPONENT_REF && "not a COMPONENT_REF!");
+ tree field = TREE_OPERAND(exp, 1);
+ assert(TREE_CODE(field) == FIELD_DECL && "not a FIELD_DECL!");
+ tree field_offset = component_ref_field_offset (exp);
+ assert(DECL_FIELD_BIT_OFFSET(field) && field_offset);
+ unsigned Result = TREE_INT_CST_LOW(DECL_FIELD_BIT_OFFSET(field));
+ if (TREE_CODE(field_offset) == INTEGER_CST)
+ Result += TREE_INT_CST_LOW(field_offset)*8;
+ return Result;
+}
+
LValue TreeToLLVM::EmitLV_COMPONENT_REF(tree exp) {
LValue StructAddrLV = EmitLV(TREE_OPERAND(exp, 0));
tree FieldDecl = TREE_OPERAND(exp, 1);
@@ -4610,11 +4624,12 @@
// BitStart - This is the actual offset of the field from the start of the
// struct, in bits. For bitfields this may be on a non-byte boundary.
- unsigned BitStart = getFieldOffsetInBits(FieldDecl);
+ unsigned BitStart = getComponentRefOffsetInBits(exp);
Value *FieldPtr;
+ tree field_offset = component_ref_field_offset (exp);
// If this is a normal field at a fixed offset from the start, handle it.
- if (TREE_CODE(DECL_FIELD_OFFSET(FieldDecl)) == INTEGER_CST) {
+ if (TREE_CODE(field_offset) == INTEGER_CST) {
assert(DECL_LLVM_SET_P(FieldDecl) && "Struct not laid out for LLVM?");
ConstantInt *CI = cast<ConstantInt>(DECL_LLVM(FieldDecl));
uint32_t MemberIndex = CI->getZExtValue();
@@ -4638,7 +4653,7 @@
}
} else {
- Value *Offset = Emit(DECL_FIELD_OFFSET(FieldDecl), 0);
+ Value *Offset = Emit(field_offset, 0);
Value *Ptr = CastToType(Instruction::PtrToInt, StructAddrLV.Ptr,
Offset->getType());
Ptr = BinaryOperator::createAdd(Ptr, Offset, "tmp", CurBB);
@@ -5662,13 +5677,14 @@
// BitStart - This is the actual offset of the field from the start of the
// struct, in bits. For bitfields this may be on a non-byte boundary.
- unsigned BitStart = getFieldOffsetInBits(FieldDecl);
+ unsigned BitStart = getComponentRefOffsetInBits(exp);
unsigned BitSize = 0;
Constant *FieldPtr;
const TargetData &TD = getTargetData();
-
+
+ tree field_offset = component_ref_field_offset (exp);
// If this is a normal field at a fixed offset from the start, handle it.
- if (TREE_CODE(DECL_FIELD_OFFSET(FieldDecl)) == INTEGER_CST) {
+ if (TREE_CODE(field_offset) == INTEGER_CST) {
assert(DECL_LLVM_SET_P(FieldDecl) && "Struct not laid out for LLVM?");
ConstantInt *CI = cast<ConstantInt>(DECL_LLVM(FieldDecl));
uint64_t MemberIndex = CI->getZExtValue();
@@ -5688,18 +5704,18 @@
}
} else {
// We were unable to make a nice offset, emit an ugly one.
- Constant *Offset = Convert(DECL_FIELD_OFFSET(FieldDecl));
+ Constant *Offset = Convert(field_offset);
FieldPtr = ConstantExpr::getPtrToInt(StructAddrLV, Offset->getType());
FieldPtr = ConstantExpr::getAdd(FieldPtr, Offset);
FieldPtr = ConstantExpr::getIntToPtr(FieldPtr, PointerType::get(FieldTy));
// Do horrible pointer arithmetic to get the address of the field.
- unsigned ByteOffset = TREE_INT_CST_LOW(DECL_FIELD_OFFSET(FieldDecl));
+ unsigned ByteOffset = TREE_INT_CST_LOW(field_offset);
BitStart -= ByteOffset * 8;
}
} else {
- Constant *Offset = Convert(DECL_FIELD_OFFSET(FieldDecl));
+ Constant *Offset = Convert(field_offset);
Constant *Ptr = ConstantExpr::getPtrToInt(StructAddrLV, Offset->getType());
Ptr = ConstantExpr::getAdd(Ptr, Offset);
FieldPtr = ConstantExpr::getIntToPtr(Ptr, PointerType::get(FieldTy));
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