[Lldb-commits] [lldb] fdede92 - [lldb][DWARF] Sort ranges list in dwarf 5. (#91343)

[via lldb-commits]

Author: Zequan Wu
Date: 2024-05-09T10:42:53-04:00
New Revision: fdede92d435068f31e7ea3a1dddb46d50343dd8c

URL: https://github.com/llvm/llvm-project/commit/fdede92d435068f31e7ea3a1dddb46d50343dd8c
DIFF: https://github.com/llvm/llvm-project/commit/fdede92d435068f31e7ea3a1dddb46d50343dd8c.diff

LOG: [lldb][DWARF] Sort ranges list in dwarf 5. (#91343)

Dwarf 5 says "There is no requirement that the entries be ordered in any
particular way" in 2.17.3 Non-Contiguous Address Ranges for rnglist.
Some places assume the ranges are already sorted but it's not.

For example, when [parsing function
info](https://github.com/llvm/llvm-project/blob/bc8a42762057d7036f6871211e62b1c3efb2738a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp#L922-L927),
it validates low and hi address of the function: GetMinRangeBase returns
the first range entry base and GetMaxRangeEnd returns the last range
end. If low >= hi, it stops parsing this function. This causes missing
inline stack frames for those functions.

This change fixes it and updates the test
`lldb/test/Shell/SymbolFile/DWARF/x86/debug_rnglists.s` so that two
ranges in `.debug_rnglists` are out of order and `image lookup -v -s
lookup_rnglists` is still able to produce sorted ranges for the inner
block.

Added: 
    

Modified: 
    lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
    lldb/test/Shell/SymbolFile/DWARF/x86/debug_rnglists.s

Removed: 
    


################################################################################
diff  --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
index dabc595427dfa..3a57ec970b071 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
@@ -1062,6 +1062,7 @@ DWARFUnit::FindRnglistFromOffset(dw_offset_t offset) {
     ranges.Append(DWARFRangeList::Entry(llvm_range.LowPC,
                                         llvm_range.HighPC - llvm_range.LowPC));
   }
+  ranges.Sort();
   return ranges;
 }
 

diff  --git a/lldb/test/Shell/SymbolFile/DWARF/x86/debug_rnglists.s b/lldb/test/Shell/SymbolFile/DWARF/x86/debug_rnglists.s
index 89b5d94c68c3b..af8a1796f3abe 100644
--- a/lldb/test/Shell/SymbolFile/DWARF/x86/debug_rnglists.s
+++ b/lldb/test/Shell/SymbolFile/DWARF/x86/debug_rnglists.s
@@ -124,12 +124,12 @@ lookup_rnglists2:
 .Lrnglists_table_base0:
         .long   .Ldebug_ranges0-.Lrnglists_table_base0
 .Ldebug_ranges0:
-        .byte   4                       # DW_RLE_offset_pair
-        .uleb128 .Lblock1_begin-rnglists  #   starting offset
-        .uleb128 .Lblock1_end-rnglists    #   ending offset
         .byte   4                       # DW_RLE_offset_pair
         .uleb128 .Lblock2_begin-rnglists  #   starting offset
         .uleb128 .Lblock2_end-rnglists    #   ending offset
+        .byte   4                       # DW_RLE_offset_pair
+        .uleb128 .Lblock1_begin-rnglists  #   starting offset
+        .uleb128 .Lblock1_end-rnglists    #   ending offset
         .byte   0                       # DW_RLE_end_of_list
 .Ldebug_rnglist_table_end0: