[GR-58500] Incorrect address location for compressed hub references in DWARF debuginfo.

substratevm/debug/gdbpy/gdb-debughelpers.py

@@ -100,8 +100,8 @@ class SVMUtil:
     compressed_ref_prefix = '_z_.'
 
     use_heap_base = try_or_else(lambda: bool(gdb.parse_and_eval('(int)__svm_use_heap_base')), True, gdb.error)
-    compressed_shift = try_or_else(lambda: int(gdb.parse_and_eval('(int)__svm_compressed_shift')), 0, gdb.error)
-    oop_tags_mask = try_or_else(lambda: int(gdb.parse_and_eval('(int)__svm_oop_tags_mask')), 0, gdb.error)
+    compression_shift = try_or_else(lambda: int(gdb.parse_and_eval('(int)__svm_compression_shift')), 0, gdb.error)
+    reserved_bits_mask = try_or_else(lambda: int(gdb.parse_and_eval('(int)__svm_reserved_bits_mask')), 0, gdb.error)
     object_alignment = try_or_else(lambda: int(gdb.parse_and_eval('(int)__svm_object_alignment')), 0, gdb.error)
 
     string_type = gdb.lookup_type("java.lang.String")
@@ -190,31 +190,34 @@ def get_compressed_type(cls, t: gdb.Type) -> gdb.Type:
         return gdb.lookup_type(type_name)
 
     @classmethod
-    def get_compressed_adr(cls, obj: gdb.Value) -> int:
+    def get_compressed_oop(cls, obj: gdb.Value) -> int:
         # use compressed ref if available - only compute it if necessary
         if obj.type.code == gdb.TYPE_CODE_PTR and cls.is_compressed(obj.type):
             return int(obj)
 
-        absolute_adr = adr(obj)
-        if absolute_adr == 0:
-            return absolute_adr
+        obj_adr = adr(obj)
+        if obj_adr == 0:
+            return obj_adr
 
-        # recreate correct address for compressed oops
-        # For an explanation of the conversion rules see com.oracle.svm.core.heap.ReferenceAccess
+        # recreate compressed oop from the object address
+        # this reverses the uncompress expression from
+        # com.oracle.objectfile.elf.dwarf.DwarfInfoSectionImpl#writeIndirectOopConversionExpression
         is_hub = cls.get_rtt(obj) == cls.hub_type
-        oop_compressed_shift = cls.compressed_shift
-        oop_tag_shift = int.bit_count(cls.oop_tags_mask)
-        oop_align_shift = int.bit_count(cls.object_alignment - 1)
-        compressed_adr = absolute_adr
+        compression_shift = cls.compression_shift
+        num_reserved_bits = int.bit_count(cls.reserved_bits_mask)
+        num_alignment_bits = int.bit_count(cls.object_alignment - 1)
+        compressed_oop = obj_adr
         if cls.use_heap_base:
-            compressed_adr -= int(SVMUtil.get_heap_base())
-            if is_hub:
-                if oop_compressed_shift == 0:
-                    oop_compressed_shift = oop_align_shift
-                compressed_adr = compressed_adr << oop_tag_shift
-            compressed_adr = compressed_adr >> oop_compressed_shift
+            compressed_oop -= int(SVMUtil.get_heap_base())
+            assert compression_shift >= 0
+            compressed_oop = compressed_oop >> compression_shift
+        if is_hub:
+            assert num_alignment_bits >= 0
+            compressed_oop = compressed_oop << num_alignment_bits
+            assert num_reserved_bits >= 0
+            compressed_oop = compressed_oop >> num_reserved_bits
 
-        return compressed_adr
+        return compressed_oop
 
     @classmethod
     def get_unqualified_type_name(cls, qualified_type_name: str) -> str:
@@ -237,7 +240,7 @@ def is_compressed(cls, t: gdb.Type) -> bool:
     @classmethod
     def adr_str(cls, obj: gdb.Value) -> str:
         if not svm_print_address.absolute_adr and cls.is_compressed(obj.type):
-            result = f' @z({hex(cls.get_compressed_adr(obj))})'
+            result = f' @z({hex(cls.get_compressed_oop(obj))})'
         else:
             result = f' @({hex(adr(obj))})'
         trace(f'<SVMUtil> - adr_str({hex(adr(obj))}) = {result}')
@@ -440,9 +443,9 @@ def cast_to(cls, obj: gdb.Value, t: gdb.Type) -> gdb.Value:
 
         # get objects address, take care of compressed oops
         if cls.is_compressed(t):
-            obj_adr = cls.get_compressed_adr(obj)
+            obj_oop = cls.get_compressed_oop(obj)
         else:
-            obj_adr = adr(obj)
+            obj_oop = adr(obj)
 
         trace(f'<SVMUtil> - cast_to({hex(adr(obj))}, {t})')
         if t.code != gdb.TYPE_CODE_PTR:
@@ -451,7 +454,7 @@ def cast_to(cls, obj: gdb.Value, t: gdb.Type) -> gdb.Value:
         trace(f'<SVMUtil> - cast_to({hex(adr(obj))}, {t}) returned')
         # just use the raw pointer value and cast it instead the obj
         # casting the obj directly results in issues with compressed oops
-        return obj if t == obj.type else gdb.Value(obj_adr).cast(t)
+        return obj if t == obj.type else gdb.Value(obj_oop).cast(t)
 
     @classmethod
     def get_symbol_adr(cls, symbol: str) -> int:
@@ -1236,8 +1239,8 @@ def cast_to_rtt(obj: gdb.Value, obj_str: str) -> tuple:  # tuple[gdb.Value, str]
         if static_type.name == rtt.name:
             return obj, obj_str
         else:
-            obj_adr = SVMUtil.get_compressed_adr(obj) if SVMUtil.is_compressed(rtt) else adr(obj)
-            return obj, f"(('{rtt.name}' *)({obj_adr}))"
+            obj_oop = SVMUtil.get_compressed_oop(obj) if SVMUtil.is_compressed(rtt) else adr(obj)
+            return obj, f"(('{rtt.name}' *)({obj_oop}))"
 
     # Define the token specifications
     token_specification = [

substratevm/src/com.oracle.objectfile/src/com/oracle/objectfile/debugentry/DebugInfoBase.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2024, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2020, 2020, Red Hat Inc. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -167,27 +167,31 @@ public abstract class DebugInfoBase {
     /**
      * Number of bits oops are left shifted by when using compressed oops.
      */
-    private int oopCompressShift;
+    private int compressionShift;
+    /**
+     * Bit mask used for tagging oops.
+     */
+    private int reservedBitsMask;
     /**
      * Number of low order bits used for tagging oops.
      */
-    private int oopTagsCount;
+    private int numReservedBits;
     /**
      * Number of bytes used to store an oop reference.
      */
-    private int oopReferenceSize;
+    private int referenceSize;
     /**
      * Number of bytes used to store a raw pointer.
      */
     private int pointerSize;
     /**
      * Alignment of object memory area (and, therefore, of any oop) in bytes.
      */
-    private int oopAlignment;
+    private int objectAlignment;
     /**
      * Number of bits in oop which are guaranteed 0 by virtue of alignment.
      */
-    private int oopAlignShift;
+    private int numAlignmentBits;
     /**
      * The compilation directory in which to look for source files as a {@link String}.
      */
@@ -207,12 +211,13 @@ public abstract class DebugInfoBase {
     public DebugInfoBase(ByteOrder byteOrder) {
         this.byteOrder = byteOrder;
         this.useHeapBase = true;
-        this.oopTagsCount = 0;
-        this.oopCompressShift = 0;
-        this.oopReferenceSize = 0;
+        this.reservedBitsMask = 0;
+        this.numReservedBits = 0;
+        this.compressionShift = 0;
+        this.referenceSize = 0;
         this.pointerSize = 0;
-        this.oopAlignment = 0;
-        this.oopAlignShift = 0;
+        this.objectAlignment = 0;
+        this.numAlignmentBits = 0;
         this.hubClassEntry = null;
         this.compiledCodeMax = 0;
         // create and index an empty dir with index 0.
@@ -245,35 +250,33 @@ public void installDebugInfo(DebugInfoProvider debugInfoProvider) {
         /*
          * Save count of low order tag bits that may appear in references.
          */
-        int oopTagsMask = debugInfoProvider.oopTagsMask();
+        reservedBitsMask = debugInfoProvider.reservedBitsMask();
 
-        /* Tag bits must be between 0 and 32 for us to emit as DW_OP_lit<n>. */
-        assert oopTagsMask >= 0 && oopTagsMask < 32;
         /* Mask must be contiguous from bit 0. */
-        assert ((oopTagsMask + 1) & oopTagsMask) == 0;
+        assert ((reservedBitsMask + 1) & reservedBitsMask) == 0;
 
-        oopTagsCount = Integer.bitCount(oopTagsMask);
+        numReservedBits = Integer.bitCount(reservedBitsMask);
 
         /* Save amount we need to shift references by when loading from an object field. */
-        oopCompressShift = debugInfoProvider.oopCompressShift();
+        compressionShift = debugInfoProvider.compressionShift();
 
         /* shift bit count must be either 0 or 3 */
-        assert (oopCompressShift == 0 || oopCompressShift == 3);
+        assert (compressionShift == 0 || compressionShift == 3);
 
         /* Save number of bytes in a reference field. */
-        oopReferenceSize = debugInfoProvider.oopReferenceSize();
+        referenceSize = debugInfoProvider.referenceSize();
 
         /* Save pointer size of current target. */
         pointerSize = debugInfoProvider.pointerSize();
 
         /* Save alignment of a reference. */
-        oopAlignment = debugInfoProvider.oopAlignment();
+        objectAlignment = debugInfoProvider.objectAlignment();
 
         /* Save alignment of a reference. */
-        oopAlignShift = Integer.bitCount(oopAlignment - 1);
+        numAlignmentBits = Integer.bitCount(objectAlignment - 1);
 
         /* Reference alignment must be 8 bytes. */
-        assert oopAlignment == 8;
+        assert objectAlignment == 8;
 
         /* retrieve limit for Java code address range */
         compiledCodeMax = debugInfoProvider.compiledCodeMax();
@@ -702,32 +705,32 @@ public boolean useHeapBase() {
         return useHeapBase;
     }
 
-    public byte oopTagsMask() {
-        return (byte) ((1 << oopTagsCount) - 1);
+    public int reservedBitsMask() {
+        return reservedBitsMask;
     }
 
-    public byte oopTagsShift() {
-        return (byte) oopTagsCount;
+    public int numReservedBits() {
+        return numReservedBits;
     }
 
-    public int oopCompressShift() {
-        return oopCompressShift;
+    public int compressionShift() {
+        return compressionShift;
     }
 
-    public int oopReferenceSize() {
-        return oopReferenceSize;
+    public int referenceSize() {
+        return referenceSize;
     }
 
     public int pointerSize() {
         return pointerSize;
     }
 
-    public int oopAlignment() {
-        return oopAlignment;
+    public int objectAlignment() {
+        return objectAlignment;
     }
 
-    public int oopAlignShift() {
-        return oopAlignShift;
+    public int numAlignmentBits() {
+        return numAlignmentBits;
     }
 
     public String getCachePath() {

substratevm/src/com.oracle.objectfile/src/com/oracle/objectfile/debuginfo/DebugInfoProvider.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2024, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2020, 2020, Red Hat Inc. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -47,17 +47,17 @@ public interface DebugInfoProvider {
     /**
      * Number of bits oops are left shifted by when using compressed oops.
      */
-    int oopCompressShift();
+    int compressionShift();
 
     /**
      * Mask selecting low order bits used for tagging oops.
      */
-    int oopTagsMask();
+    int reservedBitsMask();
 
     /**
      * Number of bytes used to store an oop reference.
      */
-    int oopReferenceSize();
+    int referenceSize();
 
     /**
      * Number of bytes used to store a raw pointer.
@@ -67,7 +67,7 @@ public interface DebugInfoProvider {
     /**
      * Alignment of object memory area (and, therefore, of any oop) in bytes.
      */
-    int oopAlignment();
+    int objectAlignment();
 
     int compiledCodeMax();