Author: johannes
Date: Tue Jan 8 15:08:57 2008
New Revision: 45757
URL: http://llvm.org/viewvc/llvm-project?rev=45757&view=rev
Log:
Fix gcc->llvm translation for virtual base classes. pr1746
Modified:
llvm-gcc-4.2/trunk/gcc/llvm-types.cpp
llvm-gcc-4.2/trunk/gcc/tree.c
llvm-gcc-4.2/trunk/gcc/tree.h
Modified: llvm-gcc-4.2/trunk/gcc/llvm-types.cpp
URL:
http://llvm.org/viewvc/llvm-project/llvm-gcc-4.2/trunk/gcc/llvm-types.cpp?rev=45757&r1=45756&r2=45757&view=diff
==============================================================================
--- llvm-gcc-4.2/trunk/gcc/llvm-types.cpp (original)
+++ llvm-gcc-4.2/trunk/gcc/llvm-types.cpp Tue Jan 8 15:08:57 2008
@@ -1614,6 +1614,129 @@
}
+/// Mapping from type to type-used-as-base-class and back.
+static DenseMap<tree, tree> BaseTypesMap;
+
+/// FixBaseClassField - This method is called when we have a field Field
+/// of Record type within a Record, and the size of Field is smaller than the
+/// size of its Record type. This may indicate the situation where a base
class
+/// has virtual base classes which are not allocated. Replace Field's original
+/// type with a modified one reflecting what actually gets allocated.
+///
+/// This can also occur when a class has an empty base class; the class will
+/// have size N+4 and the field size N+1. In this case the fields will add
+/// up to N+4, so we haven't really changed anything.
+
+static tree FixBaseClassField(tree Field) {
+ tree oldTy = TREE_TYPE(Field);
+ tree &newTy = BaseTypesMap[oldTy];
+ // If already in table, reuse.
+ if (!newTy) {
+ newTy = copy_node(oldTy);
+ tree F2 = 0, prevF2 = 0;
+ // Copy the fields up to the TYPE_DECL separator.
+ // VAR_DECLs can also appear, representing static members. Possibly some
+ // other junk I haven't hit yet, just skip anything that's not a FIELD:(
+ for (tree F = TYPE_FIELDS(oldTy); F; prevF2 = F2, F = TREE_CHAIN(F)) {
+ if (TREE_CODE(F) == TYPE_DECL)
+ break;
+ if (TREE_CODE(F) == FIELD_DECL) {
+ F2 = copy_node(F);
+ if (prevF2)
+ TREE_CHAIN(prevF2) = F2;
+ else
+ TYPE_FIELDS(newTy) = F2;
+ TREE_CHAIN(F2) = 0;
+ }
+ }
+ BaseTypesMap[oldTy] = newTy;
+ BaseTypesMap[newTy] = oldTy;
+ /* Prevent gcc's garbage collector from destroying newTy. The
+ GC code doesn't understand DenseMaps:( */
+ llvm_note_type_used(newTy);
+ TYPE_SIZE(newTy) = DECL_SIZE(Field);
+ TYPE_SIZE_UNIT(newTy) = DECL_SIZE_UNIT(Field);
+ TYPE_MAIN_VARIANT(newTy) = newTy;
+ // Change the name.
+ if (TYPE_NAME(oldTy)) {
+ const char *p = "anon";
+ if (TREE_CODE(TYPE_NAME(oldTy)) ==IDENTIFIER_NODE)
+ p = IDENTIFIER_POINTER(TYPE_NAME(oldTy));
+ else if (DECL_NAME(TYPE_NAME(oldTy)))
+ p = IDENTIFIER_POINTER(DECL_NAME(TYPE_NAME(oldTy)));
+ char *q = (char *)xmalloc(strlen(p)+6);
+ strcpy(q,p);
+ strcat(q,".base");
+ TYPE_NAME(newTy) = get_identifier(q);
+ free(q);
+ }
+ }
+ return newTy;
+}
+
+/// FixBaseClassFields - alter the types referred to by Field nodes that
+/// represent base classes to reflect reality.
+//
+// Suppose we're converting type T. Look for the case where a base class A
+// of T contains a virtual base class B, and B is not allocated when A is
+// used as the base class of T. This is indicated by the FIELD node for A
+// having a size smaller than the size of A, and the chain of fields for A
+// having a TYPE_DECL node in the middle of it; that node comes after the
+// allocated fields and before the unallocated virtual base classes. Create
+// a new type A.base for LLVM purposes which does not contain the virtual
+// base classes. (Where A is a virtual base class of T, there is also a BINFO
+// node for it, but not when A is a nonvirtual base class. So we can't
+// use that.)
+static void FixBaseClassFields(tree type) {
+ assert(TREE_CODE(type)==RECORD_TYPE);
+ for (tree Field = TYPE_FIELDS(type); Field; Field = TREE_CHAIN(Field)) {
+ if (TREE_CODE(Field)==FIELD_DECL &&
+ !DECL_BIT_FIELD_TYPE(Field) &&
+ TREE_CODE(DECL_FIELD_OFFSET(Field))==INTEGER_CST &&
+ TREE_CODE(TREE_TYPE(Field))==RECORD_TYPE &&
+ TYPE_SIZE(TREE_TYPE(Field)) &&
+ DECL_SIZE(Field) &&
+ TREE_INT_CST_LOW(DECL_SIZE(Field)) <
+ TREE_INT_CST_LOW(TYPE_SIZE(TREE_TYPE(Field))))
+ TREE_TYPE(Field) = FixBaseClassField(Field);
+ }
+ // Size of the complete type will be a multiple of its alignment.
+ // In some cases involving empty C++ classes this is not true coming in.
+ // Earlier, the sizes in the field types were also wrong in a way that
+ // compensated as far as LLVM's translation code is concerned; now we
+ // have fixed that, and have to fix the size also.
+ if (TYPE_SIZE (type) && TREE_CODE(TYPE_SIZE(type)) == INTEGER_CST) {
+ TYPE_SIZE(type) = build_int_cst(
+ TREE_TYPE(TYPE_SIZE(type)),
+ (TREE_INT_CST_LOW(TYPE_SIZE(type))+TYPE_ALIGN(type)-1) &
+ ~(TYPE_ALIGN(type)-1));
+ TYPE_SIZE_UNIT(type) = build_int_cst(
+ TREE_TYPE(TYPE_SIZE_UNIT(type)),
+ (TREE_INT_CST_LOW(TYPE_SIZE_UNIT(type))+TYPE_ALIGN_UNIT(type)-1) &
+ ~(TYPE_ALIGN_UNIT(type)-1));
+ }
+}
+
+// RestoreBaseClassFields - put things back the way they were so the C++FE
+// code continues to work (there are pointers stashed away in there).
+
+static void RestoreBaseClassFields(tree type) {
+ assert(TREE_CODE(type)==RECORD_TYPE);
+ for (tree Field = TYPE_FIELDS(type); Field; Field = TREE_CHAIN(Field)) {
+ if (TREE_CODE(Field)==FIELD_DECL &&
+ !DECL_BIT_FIELD_TYPE(Field) &&
+ TREE_CODE(DECL_FIELD_OFFSET(Field))==INTEGER_CST &&
+ TREE_CODE(TREE_TYPE(Field))==RECORD_TYPE &&
+ TYPE_SIZE(TREE_TYPE(Field)) &&
+ DECL_SIZE(Field)) {
+ tree &oldTy = BaseTypesMap[TREE_TYPE(Field)];
+ if (oldTy)
+ TREE_TYPE(Field) = oldTy;
+ }
+ }
+}
+
+
/// DecodeStructFields - This method decodes the specified field, if it is a
/// FIELD_DECL, adding or updating the specified StructTypeConversionInfo to
@@ -1794,7 +1917,11 @@
// TYPE_DECL node sitting in the middle of the FIELD list separating virtual
// base classes from everything else.
//
-// For LLVM purposes, we probably need to build a new type for B-within-D that
+// Similarly, a nonvirtual base class which has virtual base classes might
+// not contain those virtual base classes when used as a nonvirtual base class.
+// There is seemingly no way to detect this except for the size differential.
+//
+// For LLVM purposes, we build a new type for B-within-D that
// has the correct size and layout for that usage.
const Type *TypeConverter::ConvertRECORD(tree type, tree orig_type) {
@@ -1815,18 +1942,14 @@
bool OldConvertingStruct = ConvertingStruct;
ConvertingStruct = true;
- // Construct LLVM types for the base types... in order to get names for
- // base classes and to ensure they are laid out.
- if (tree binfo = TYPE_BINFO(type)) {
- for (unsigned i = 0, e = BINFO_N_BASE_BINFOS(binfo); i != e; ++i)
- ConvertType(BINFO_TYPE(BINFO_BASE_BINFO(binfo, i)));
- }
-
StructTypeConversionInfo *Info =
new StructTypeConversionInfo(*TheTarget, TYPE_ALIGN_UNIT(type),
TYPE_PACKED(type));
+
+ // Alter any fields that appear to represent base classes so their lists
+ // of fields bear some resemblance to reality.
+ FixBaseClassFields(type);
-
// Convert over all of the elements of the struct.
for (tree Field = TYPE_FIELDS(type); Field; Field = TREE_CHAIN(Field))
DecodeStructFields(Field, *Info);
@@ -1906,7 +2029,11 @@
Info->getLLVMFieldFor(FieldOffsetInBits, CurFieldNo, isZeroSizeField);
SetFieldIndex(Field, FieldNo);
}
-
+
+ // Put the original gcc struct back the way it was; necessary to prevent the
+ // binfo-walking code in cp/class from getting confused.
+ RestoreBaseClassFields(type);
+
const Type *ResultTy = Info->getLLVMType();
StructTypeInfoMap[ResultTy] = Info;
Modified: llvm-gcc-4.2/trunk/gcc/tree.c
URL:
http://llvm.org/viewvc/llvm-project/llvm-gcc-4.2/trunk/gcc/tree.c?rev=45757&r1=45756&r2=45757&view=diff
==============================================================================
--- llvm-gcc-4.2/trunk/gcc/tree.c (original)
+++ llvm-gcc-4.2/trunk/gcc/tree.c Tue Jan 8 15:08:57 2008
@@ -7902,4 +7902,16 @@
}
/* APPLE LOCAL end CW asm blocks */
+/* LLVM LOCAL begin */
+/* This data structure keeps gcc's garbage collector from
+ deleting types created by the llvm virtual base class handling
+ stuff in llvm-types.cpp. */
+static GTY(()) VEC(tree,gc) *llvm_types_used;
+
+void
+llvm_note_type_used(tree type)
+{
+ VEC_safe_push(tree, gc, llvm_types_used, type);
+}
+/* LLVM LOCAL end */
#include "gt-tree.h"
Modified: llvm-gcc-4.2/trunk/gcc/tree.h
URL:
http://llvm.org/viewvc/llvm-project/llvm-gcc-4.2/trunk/gcc/tree.h?rev=45757&r1=45756&r2=45757&view=diff
==============================================================================
--- llvm-gcc-4.2/trunk/gcc/tree.h (original)
+++ llvm-gcc-4.2/trunk/gcc/tree.h Tue Jan 8 15:08:57 2008
@@ -4318,6 +4318,8 @@
extern tree lower_bound_in_type (tree, tree);
extern int operand_equal_for_phi_arg_p (tree, tree);
extern bool empty_body_p (tree);
+/* LLVM LOCAL */
+extern void llvm_note_type_used(tree);
/* In stmt.c */
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