[Lldb-commits] [PATCH] D70848: [LLDB] Set the right address size on output DataExtractors from ObjectFile

[Martin Storsjö via Phabricator via lldb-commits]

mstorsjo created this revision.
mstorsjo added reviewers: labath, amccarth.
Herald added a subscriber: aprantl.
Herald added a project: LLDB.

If filling in a DataExtractor from an ObjectFile, e.g. via the ReadSectionData method, the output DataExtractor gets the address size from the m_data member.

ObjectFile's m_data member is initialized without knowledge about the address size (so the address size is set based on the host's sizeof(void*), and at that point within ObjectFile's constructor, virtual methods implemented in subclasses (like GetAddressByteSize()) can't be called, therefore fix it up when filling in external DataExtractors.

This makes sure that line tables from executables with a different address size are parsed properly; previously this tripped up DWARFDebugLine::LineTable::parse for 32 bit executables on a 64 bit host, as the address size in the line table (4) didn't match the one set in the DWARFDataExtractor.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D70848

Files:
  lldb/source/Symbol/ObjectFile.cpp
  lldb/test/Shell/SymbolFile/DWARF/win-i386-line-table.s


Index: lldb/test/Shell/SymbolFile/DWARF/win-i386-line-table.s
===================================================================
--- /dev/null
+++ lldb/test/Shell/SymbolFile/DWARF/win-i386-line-table.s
@@ -0,0 +1,55 @@
+# Test that lldb can read a line table for an architecture with a different
+# address size than the one that of the host.
+
+# REQUIRES: lld, x86
+
+# RUN: llvm-mc -triple i686-windows-gnu %s -filetype=obj > %t.o
+# RUN: lld-link %t.o -out:%t.exe -debug:dwarf -entry:entry -subsystem:console -lldmingw
+# RUN: %lldb %t.exe -o "image dump line-table -v win-i386-line-table.c" -b | FileCheck %s
+
+# CHECK: Line table for win-i386-line-table.c in `win-i386-line-table.s.tmp.exe
+# CHECK: 0x00401000: /path/to/src/win-i386-line-table.c:2:1
+# CHECK: 0x00401001: /path/to/src/win-i386-line-table.c:2:1
+
+        .text
+        .file   "win-i386-line-table.c"
+        .globl  _entry                  # -- Begin function entry
+_entry:                                 # @entry
+        .file   1 "/path/to/src" "win-i386-line-table.c"
+        .loc    1 1 0                   # win-i386-line-table.c:1:0
+        .cfi_sections .debug_frame
+        .cfi_startproc
+        .loc    1 2 1 prologue_end      # win-i386-line-table.c:2:1
+        retl
+        .cfi_endproc
+                                        # -- End function
+        .section        .debug_str,"dr"
+Linfo_string1:
+        .asciz  "win-i386-line-table.c"
+        .section        .debug_abbrev,"dr"
+Lsection_abbrev:
+        .byte   1                       # Abbreviation Code
+        .byte   17                      # DW_TAG_compile_unit
+        .byte   1                       # DW_CHILDREN_yes
+        .byte   3                       # DW_AT_name
+        .byte   14                      # DW_FORM_strp
+        .byte   16                      # DW_AT_stmt_list
+        .byte   23                      # DW_FORM_sec_offset
+        .byte   0                       # EOM(1)
+        .byte   0                       # EOM(2)
+        .byte   0                       # EOM(3)
+        .section        .debug_info,"dr"
+Lsection_info:
+Lcu_begin0:
+        .long   Ldebug_info_end0-Ldebug_info_start0 # Length of Unit
+Ldebug_info_start0:
+        .short  4                       # DWARF version number
+        .secrel32       Lsection_abbrev # Offset Into Abbrev. Section
+        .byte   4                       # Address Size (in bytes)
+        .byte   1                       # Abbrev [1] 0xb:0x2d DW_TAG_compile_unit
+        .secrel32       Linfo_string1   # DW_AT_name
+        .secrel32       Lline_table_start0 # DW_AT_stmt_list
+        .byte   0                       # End Of Children Mark
+Ldebug_info_end0:
+        .section        .debug_line,"dr"
+Lline_table_start0:
Index: lldb/source/Symbol/ObjectFile.cpp
===================================================================
--- lldb/source/Symbol/ObjectFile.cpp
+++ lldb/source/Symbol/ObjectFile.cpp
@@ -477,7 +477,13 @@
                            DataExtractor &data) const {
   // The entire file has already been mmap'ed into m_data, so just copy from
   // there as the back mmap buffer will be shared with shared pointers.
-  return data.SetData(m_data, offset, length);
+  size_t ret = data.SetData(m_data, offset, length);
+  // DataExtractor::SetData copies the address byte size from m_data, but
+  // m_data's address byte size is only set from sizeof(void*), and we can't
+  // access subclasses GetAddressByteSize() when setting up m_data in the
+  // constructor.
+  data.SetAddressByteSize(GetAddressByteSize());
+  return ret;
 }
 
 size_t ObjectFile::CopyData(lldb::offset_t offset, size_t length,


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