[Lldb-commits] [lldb] a0c57a0 - Revert "[lldb] Tolerate multiple compile units with the same DWO ID (#100577)"

Pavel Labath via lldb-commits lldb-commits at lists.llvm.org
Mon Aug 12 09:44:37 PDT 2024


Author: Pavel Labath
Date: 2024-08-12T18:43:16+02:00
New Revision: a0c57a0f3c6b44ce8f2c7222d0932df85883cf06

URL: https://github.com/llvm/llvm-project/commit/a0c57a0f3c6b44ce8f2c7222d0932df85883cf06
DIFF: https://github.com/llvm/llvm-project/commit/a0c57a0f3c6b44ce8f2c7222d0932df85883cf06.diff

LOG: Revert "[lldb] Tolerate multiple compile units with the same DWO ID (#100577)"

The test appears to be flaky. Revert it while I investigate.

This reverts commits 32a62ebdeab0c10d5311cf812e021717636d4514 and
7027cc6a073cb5ae7a0ce04fa4a2dbe714615da9.

Added: 
    

Modified: 
    lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
    lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.h

Removed: 
    lldb/test/Shell/SymbolFile/DWARF/x86/dwp-hash-collision.s


################################################################################
diff  --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
index 0a52159d055bb4..66a762bf9b6854 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
@@ -97,14 +97,12 @@ void DWARFUnit::ExtractUnitDIEIfNeeded() {
         *m_dwo_id, m_first_die.GetOffset()));
     return; // Can't fetch the compile unit from the dwo file.
   }
-
-  // Link the DWO unit to this object, if it hasn't been linked already (this
-  // can happen when we have an index, and the DWO unit is parsed first).
-  if (!dwo_cu->LinkToSkeletonUnit(*this)) {
-    SetDwoError(Status::createWithFormat(
-        "multiple compile units with Dwo ID {0:x16}", *m_dwo_id));
-    return;
-  }
+  // If the skeleton compile unit gets its unit DIE parsed first, then this
+  // will fill in the DWO file's back pointer to this skeleton compile unit.
+  // If the DWO files get parsed on their own first the skeleton back link
+  // can be done manually in DWARFUnit::GetSkeletonCompileUnit() which will
+  // do a reverse lookup and cache the result.
+  dwo_cu->SetSkeletonUnit(this);
 
   DWARFBaseDIE dwo_cu_die = dwo_cu->GetUnitDIEOnly();
   if (!dwo_cu_die.IsValid()) {
@@ -720,11 +718,13 @@ DWARFCompileUnit *DWARFUnit::GetSkeletonUnit() {
   return llvm::dyn_cast_or_null<DWARFCompileUnit>(m_skeleton_unit);
 }
 
-bool DWARFUnit::LinkToSkeletonUnit(DWARFUnit &skeleton_unit) {
-  if (m_skeleton_unit && m_skeleton_unit != &skeleton_unit)
-    return false;
-  m_skeleton_unit = &skeleton_unit;
-  return true;
+void DWARFUnit::SetSkeletonUnit(DWARFUnit *skeleton_unit) {
+  // If someone is re-setting the skeleton compile unit backlink, make sure
+  // it is setting it to a valid value when it wasn't valid, or if the
+  // value in m_skeleton_unit was valid, it should be the same value.
+  assert(skeleton_unit);
+  assert(m_skeleton_unit == nullptr || m_skeleton_unit == skeleton_unit);
+  m_skeleton_unit = skeleton_unit;
 }
 
 bool DWARFUnit::Supports_DW_AT_APPLE_objc_complete_type() {

diff  --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.h b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.h
index 209104fe3a054e..85c37971ced8e0 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.h
@@ -170,7 +170,7 @@ class DWARFUnit : public UserID {
   /// both cases correctly and avoids crashes.
   DWARFCompileUnit *GetSkeletonUnit();
 
-  bool LinkToSkeletonUnit(DWARFUnit &skeleton_unit);
+  void SetSkeletonUnit(DWARFUnit *skeleton_unit);
 
   bool Supports_DW_AT_APPLE_objc_complete_type();
 

diff  --git a/lldb/test/Shell/SymbolFile/DWARF/x86/dwp-hash-collision.s b/lldb/test/Shell/SymbolFile/DWARF/x86/dwp-hash-collision.s
deleted file mode 100644
index 7e106d6e9c2de4..00000000000000
--- a/lldb/test/Shell/SymbolFile/DWARF/x86/dwp-hash-collision.s
+++ /dev/null
@@ -1,145 +0,0 @@
-## Test that lldb handles (mainly, that it doesn't crash) the situation where
-## two skeleton compile units have the same DWO ID (and try to claim the same
-## split unit from the DWP file. This can sometimes happen when the compile unit
-## is nearly empty (e.g. because LTO has optimized all of it away).
-
-# Is flaky on Windows on Arm.
-# UNSUPPORTED: system-windows
-
-# RUN: llvm-mc -triple=x86_64-pc-linux -filetype=obj %s --defsym MAIN=0 > %t
-# RUN: llvm-mc -triple=x86_64-pc-linux -filetype=obj %s > %t.dwp
-# RUN: %lldb %t -o "image lookup -t my_enum_type" \
-# RUN:   -o "image dump separate-debug-info" -o exit | FileCheck %s
-
-## Check that we're able to access the type within the split unit (no matter
-## which skeleton unit it ends up associated with). Completely ignoring the unit
-## might also be reasonable.
-# CHECK: image lookup -t my_enum_type
-# CHECK: 1 match found
-# CHECK:      name = "my_enum_type", byte-size = 4, compiler_type = "enum my_enum_type {
-# CHECK-NEXT: }"
-#
-## Check that we get some indication of the error.
-# CHECK: image dump separate-debug-info
-# CHECK:      Dwo ID             Err Dwo Path
-# CHECK: 0xdeadbeefbaadf00d E   multiple compile units with Dwo ID 0xdeadbeefbaadf00d
-
-.set DWO_ID, 0xdeadbeefbaadf00d
-
-## The main file.
-.ifdef MAIN
-        .section        .debug_abbrev,"", at progbits
-        .byte   1                       # Abbreviation Code
-        .byte   74                      # DW_TAG_compile_unit
-        .byte   0                       # DW_CHILDREN_no
-        .byte   0x76                    # DW_AT_dwo_name
-        .byte   8                       # DW_FORM_string
-        .byte   0                       # EOM(1)
-        .byte   0                       # EOM(2)
-        .byte   0                       # EOM(3)
-
-
-        .section        .debug_info,"", at progbits
-.irpc I,01
-.Lcu_begin\I:
-        .long   .Ldebug_info_end\I-.Ldebug_info_start\I # Length of Unit
-.Ldebug_info_start\I:
-        .short  5                       # DWARF version number
-        .byte   4                       # DWARF Unit Type
-        .byte   8                       # Address Size (in bytes)
-        .long   .debug_abbrev           # Offset Into Abbrev. Section
-        .quad   DWO_ID                  # DWO id
-        .byte   1                       # Abbrev [1] DW_TAG_compile_unit
-        .ascii  "foo"
-        .byte   '0' + \I
-        .asciz  ".dwo\0"                # DW_AT_dwo_name
-.Ldebug_info_end\I:
-.endr
-
-.else
-## DWP file starts here.
-
-        .section        .debug_abbrev.dwo,"e", at progbits
-.LAbbrevBegin:
-        .byte   1                       # Abbreviation Code
-        .byte   17                      # DW_TAG_compile_unit
-        .byte   1                       # DW_CHILDREN_yes
-        .byte   37                      # DW_AT_producer
-        .byte   8                       # DW_FORM_string
-        .byte   19                      # DW_AT_language
-        .byte   5                       # DW_FORM_data2
-        .byte   0                       # EOM(1)
-        .byte   0                       # EOM(2)
-        .byte   2                       # Abbreviation Code
-        .byte   4                       # DW_TAG_enumeration_type
-        .byte   0                       # DW_CHILDREN_no
-        .byte   3                       # DW_AT_name
-        .byte   8                       # DW_FORM_string
-        .byte   73                      # DW_AT_type
-        .byte   19                      # DW_FORM_ref4
-        .byte   11                      # DW_AT_byte_size
-        .byte   11                      # DW_FORM_data1
-        .byte   0                       # EOM(1)
-        .byte   0                       # EOM(2)
-        .byte   4                       # Abbreviation Code
-        .byte   36                      # DW_TAG_base_type
-        .byte   0                       # DW_CHILDREN_no
-        .byte   3                       # DW_AT_name
-        .byte   8                       # DW_FORM_string
-        .byte   62                      # DW_AT_encoding
-        .byte   11                      # DW_FORM_data1
-        .byte   11                      # DW_AT_byte_size
-        .byte   11                      # DW_FORM_data1
-        .byte   0                       # EOM(1)
-        .byte   0                       # EOM(2)
-        .byte   0                       # EOM(3)
-.LAbbrevEnd:
-        .section        .debug_info.dwo,"e", at progbits
-.LCUBegin:
-.Lcu_begin1:
-        .long   .Ldebug_info_end1-.Ldebug_info_start1 # Length of Unit
-.Ldebug_info_start1:
-        .short  5                       # DWARF version number
-        .byte   5                       # DWARF Unit Type
-        .byte   8                       # Address Size (in bytes)
-        .long   0                       # Offset Into Abbrev. Section
-        .quad   DWO_ID                  # DWO id
-        .byte   1                       # Abbrev [1] DW_TAG_compile_unit
-        .asciz  "Hand-written DWARF"    # DW_AT_producer
-        .short  12                      # DW_AT_language
-        .byte   2                       # Abbrev [2] DW_TAG_enumeration_type
-        .asciz  "my_enum_type"          # DW_AT_name
-        .long   .Lint-.Lcu_begin1       # DW_AT_type
-        .byte   4                       # DW_AT_byte_size
-.Lint:
-        .byte   4                       # Abbrev [4] DW_TAG_base_type
-        .asciz  "int"                   # DW_AT_name
-        .byte   5                       # DW_AT_encoding
-        .byte   4                       # DW_AT_byte_size
-        .byte   0                       # End Of Children Mark
-.Ldebug_info_end1:
-.LCUEnd:
-        .section .debug_cu_index, "", @progbits
-## Header:
-        .short 5                        # Version
-        .short 0                        # Padding
-        .long 2                         # Section count
-        .long 1                         # Unit count
-        .long 2                         # Slot count
-## Hash Table of Signatures:
-        .quad 0
-        .quad DWO_ID
-## Parallel Table of Indexes:
-        .long 0
-        .long 1
-## Table of Section Offsets:
-## Row 0:
-        .long 1                         # DW_SECT_INFO
-        .long 3                         # DW_SECT_ABBREV
-## Row 1:
-        .long 0                         # Offset in .debug_info.dwo
-        .long 0                         # Offset in .debug_abbrev.dwo
-## Table of Section Sizes:
-        .long .LCUEnd-.LCUBegin         # Size in .debug_info.dwo
-        .long .LAbbrevEnd-.LAbbrevBegin # Size in .debug_abbrev.dwo
-.endif


        


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