[Lldb-commits] [lldb] r268110 - Watch out for compilers that generate bad bitfield info. If the bit size of a bitfield member doesn't lie within the bit bounds of the type itself, just leave it out so we don't get clang asserting and killing our IDE when it gets unhappy with the information.

[Greg Clayton via lldb-commits]

Author: gclayton
Date: Fri Apr 29 16:26:46 2016
New Revision: 268110

URL: http://llvm.org/viewvc/llvm-project?rev=268110&view=rev
Log:
Watch out for compilers that generate bad bitfield info. If the bit size of a bitfield member doesn't lie within the bit bounds of the type itself, just leave it out so we don't get clang asserting and killing our IDE when it gets unhappy with the information.

https://llvm.org/bugs/show_bug.cgi?id=27515
<rdar://problem/21082998>


Modified:
    lldb/trunk/packages/Python/lldbsuite/test/lang/c/bitfields/TestBitfields.py
    lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp

Modified: lldb/trunk/packages/Python/lldbsuite/test/lang/c/bitfields/TestBitfields.py
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/packages/Python/lldbsuite/test/lang/c/bitfields/TestBitfields.py?rev=268110&r1=268109&r2=268110&view=diff
==============================================================================
--- lldb/trunk/packages/Python/lldbsuite/test/lang/c/bitfields/TestBitfields.py (original)
+++ lldb/trunk/packages/Python/lldbsuite/test/lang/c/bitfields/TestBitfields.py Fri Apr 29 16:26:46 2016
@@ -22,7 +22,6 @@ class BitfieldsTestCase(TestBase):
 
     @skipIfWindows # BitFields exhibit crashes in record layout on Windows (http://llvm.org/pr21800)
     @skipIf("llvm.org/pr27510", oslist=["linux"], compiler="clang", compiler_version=[">=", "3.9"]) # expectedFailure, skip to avoid crash
-    @skipIf("llvm.org/pr27515", oslist=["macosx"]) # Assertion failed: (Offset >= Size), function insertPadding CGRecordLayoutBuilder.cpp
     def test_and_run_command(self):
         """Test 'frame variable ...' on a variable with bitfields."""
         self.build()

Modified: lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp?rev=268110&r1=268109&r2=268110&view=diff
==============================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp (original)
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp Fri Apr 29 16:26:46 2016
@@ -2645,6 +2645,10 @@ DWARFASTParserClang::ParseChildMembers(c
     if (!parent_die)
         return 0;
 
+    // Get the parent byte size so we can verify any members will fit
+    const uint64_t parent_byte_size = parent_die.GetAttributeValueAsUnsigned(DW_AT_byte_size, UINT64_MAX) * 8;
+    const uint64_t parent_bit_size = parent_byte_size == UINT64_MAX ? UINT64_MAX : parent_byte_size * 8;
+
     uint32_t member_idx = 0;
     BitfieldInfo last_field_info;
 
@@ -2890,10 +2894,23 @@ DWARFASTParserClang::ParseChildMembers(c
                                     if (byte_size == 0)
                                         byte_size = member_type->GetByteSize();
 
-                                    if (die.GetDWARF()->GetObjectFile()->GetByteOrder() == eByteOrderLittle)
+                                    ObjectFile *objfile = die.GetDWARF()->GetObjectFile();
+                                    if (objfile->GetByteOrder() == eByteOrderLittle)
                                     {
                                         this_field_info.bit_offset += byte_size * 8;
                                         this_field_info.bit_offset -= (bit_offset + bit_size);
+
+                                        if (this_field_info.bit_offset >= parent_bit_size)
+                                        {
+                                            objfile->GetModule()->ReportWarning("0x%8.8" PRIx64 ": %s bitfield named \"%s\" has invalid bit offset (0x%8.8" PRIx64 ") member will be ignored. Please file a bug against the compiler and include the preprocessed output for %s\n",
+                                                                                die.GetID(),
+                                                                                DW_TAG_value_to_name(tag),
+                                                                                name,
+                                                                                this_field_info.bit_offset,
+                                                                                sc.comp_unit ? sc.comp_unit->GetPath().c_str() : "the source file");
+                                            this_field_info.Clear();
+                                            continue;
+                                        }
                                     }
                                     else
                                     {