[llvm-debuginfo-analyzer] Fix crash with WebAssembly dead code #141616
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llvm#136772 Incorrect handling of 'tombstone' value for WebAssembly. llvm-debuginfo-analyzer already uses the tombstone approach to identify dead code. Currently, the tombstone value is evaluated as std::numeric_limits<uint64_t>::max(). Which is wrong as it does not take into account the 'Address Byte Size' from the Compile Unit header.
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@llvm/pr-subscribers-debuginfo @llvm/pr-subscribers-backend-webassembly Author: Carlos Alberto Enciso (CarlosAlbertoEnciso) Changes#136772 llvm-debuginfo-analyzer already uses the tombstone approach Patch is 22.80 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/141616.diff 6 Files Affected:
diff --git a/llvm/include/llvm/DebugInfo/LogicalView/Core/LVRange.h b/llvm/include/llvm/DebugInfo/LogicalView/Core/LVRange.h
index 3ec0ccb31168f..75889637e3252 100644
--- a/llvm/include/llvm/DebugInfo/LogicalView/Core/LVRange.h
+++ b/llvm/include/llvm/DebugInfo/LogicalView/Core/LVRange.h
@@ -54,11 +54,14 @@ class LVRange final : public LVObject {
LVAllocator Allocator;
LVRangesTree RangesTree;
LVRangeEntries RangeEntries;
- LVAddress Lower = MaxAddress;
+ LVAddress TombstoneAddress;
+ LVAddress Lower;
LVAddress Upper = 0;
public:
- LVRange() : LVObject(), RangesTree(Allocator) {}
+ LVRange(LVAddress Address = MaxAddress)
+ : LVObject(),
+ RangesTree(Allocator), TombstoneAddress(Address), Lower(Address) {}
LVRange(const LVRange &) = delete;
LVRange &operator=(const LVRange &) = delete;
~LVRange() = default;
@@ -75,7 +78,7 @@ class LVRange final : public LVObject {
void clear() {
RangeEntries.clear();
- Lower = MaxAddress;
+ Lower = TombstoneAddress;
Upper = 0;
}
bool empty() const { return RangeEntries.empty(); }
diff --git a/llvm/include/llvm/DebugInfo/LogicalView/Core/LVReader.h b/llvm/include/llvm/DebugInfo/LogicalView/Core/LVReader.h
index 870b53f6774a8..d8d731c4bf4a3 100644
--- a/llvm/include/llvm/DebugInfo/LogicalView/Core/LVReader.h
+++ b/llvm/include/llvm/DebugInfo/LogicalView/Core/LVReader.h
@@ -133,6 +133,10 @@ class LVReader {
// Only for ELF format. The CodeView is handled in a different way.
LVSectionIndex DotTextSectionIndex = UndefinedSectionIndex;
+ // Tombstone value. Assume 64 bits. The value is updated for each
+ // Compile Unit that is processed.
+ LVAddress TombstoneAddress = MaxAddress;
+
// Record Compilation Unit entry.
void addCompileUnitOffset(LVOffset Offset, LVScopeCompileUnit *CompileUnit) {
CompileUnits.emplace(Offset, CompileUnit);
@@ -257,6 +261,9 @@ class LVReader {
return CompileUnit->getCPUType();
}
+ void setTombstoneAddress(LVAddress Address) { TombstoneAddress = Address; }
+ LVAddress getTombstoneAddress() const { return TombstoneAddress; }
+
// Access to the scopes root.
LVScopeRoot *getScopesRoot() const { return Root; }
diff --git a/llvm/lib/DebugInfo/LogicalView/Readers/LVBinaryReader.cpp b/llvm/lib/DebugInfo/LogicalView/Readers/LVBinaryReader.cpp
index 434709f076dc5..4a9a19e50440f 100644
--- a/llvm/lib/DebugInfo/LogicalView/Readers/LVBinaryReader.cpp
+++ b/llvm/lib/DebugInfo/LogicalView/Readers/LVBinaryReader.cpp
@@ -384,8 +384,10 @@ LVRange *LVBinaryReader::getSectionRanges(LVSectionIndex SectionIndex) {
// Check if we already have a mapping for this section index.
LVSectionRanges::iterator IterSection = SectionRanges.find(SectionIndex);
if (IterSection == SectionRanges.end())
- IterSection =
- SectionRanges.emplace(SectionIndex, std::make_unique<LVRange>()).first;
+ IterSection = SectionRanges
+ .emplace(SectionIndex,
+ std::make_unique<LVRange>(getTombstoneAddress()))
+ .first;
LVRange *Range = IterSection->second.get();
assert(Range && "Range is null.");
return Range;
diff --git a/llvm/lib/DebugInfo/LogicalView/Readers/LVDWARFReader.cpp b/llvm/lib/DebugInfo/LogicalView/Readers/LVDWARFReader.cpp
index 14538c1aefa18..0a25f55c13bfc 100644
--- a/llvm/lib/DebugInfo/LogicalView/Readers/LVDWARFReader.cpp
+++ b/llvm/lib/DebugInfo/LogicalView/Readers/LVDWARFReader.cpp
@@ -426,10 +426,11 @@ void LVDWARFReader::processOneAttribute(const DWARFDie &Die,
}
}
if (FoundLowPC) {
- if (CurrentLowPC == MaxAddress)
+ if (CurrentLowPC == getTombstoneAddress())
CurrentElement->setIsDiscarded();
- // Consider the case of WebAssembly.
- CurrentLowPC += WasmCodeSectionOffset;
+ else
+ // Consider the case of WebAssembly.
+ CurrentLowPC += WasmCodeSectionOffset;
if (CurrentElement->isCompileUnit())
setCUBaseAddress(CurrentLowPC);
}
@@ -483,7 +484,8 @@ void LVDWARFReader::processOneAttribute(const DWARFDie &Die,
DWARFAddressRangesVector Ranges = RangesOrError.get();
for (DWARFAddressRange &Range : Ranges) {
// This seems to be a tombstone for empty ranges.
- if (Range.LowPC == Range.HighPC)
+ if ((Range.LowPC == Range.HighPC) ||
+ (Range.LowPC = getTombstoneAddress()))
continue;
// Store the real upper limit for the address range.
if (UpdateHighAddress && Range.HighPC > 0)
@@ -841,6 +843,11 @@ Error LVDWARFReader::createScopes() {
: DwarfContext->dwo_compile_units();
for (const std::unique_ptr<DWARFUnit> &CU : CompileUnits) {
+ // Take into account the address byte size for a correct 'tombstone'
+ // value identification.
+ setTombstoneAddress(
+ dwarf::computeTombstoneAddress(CU->getAddressByteSize()));
+
// Deduction of index used for the line records.
//
// For the following test case: test.cpp
diff --git a/llvm/test/tools/llvm-debuginfo-analyzer/WebAssembly/Inputs/test-clang-tombstone.s b/llvm/test/tools/llvm-debuginfo-analyzer/WebAssembly/Inputs/test-clang-tombstone.s
new file mode 100644
index 0000000000000..f7e85420b89dd
--- /dev/null
+++ b/llvm/test/tools/llvm-debuginfo-analyzer/WebAssembly/Inputs/test-clang-tombstone.s
@@ -0,0 +1,366 @@
+ .text
+ .file "test.cpp"
+ .globaltype __stack_pointer, i32
+ .functype _Z3fooPKijb (i32, i32, i32) -> (i32)
+ .section .text._Z3fooPKijb,"",@
+ .hidden _Z3fooPKijb # -- Begin function _Z3fooPKijb
+ .globl _Z3fooPKijb
+ .type _Z3fooPKijb,@function
+_Z3fooPKijb: # @_Z3fooPKijb
+.Lfunc_begin0:
+ .file 1 "/data/projects/scripts/regression-suite/input/general" "test.cpp"
+ .loc 1 2 0 # test.cpp:2:0
+ .functype _Z3fooPKijb (i32, i32, i32) -> (i32)
+ .local i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32
+# %bb.0: # %entry
+ global.get __stack_pointer
+ local.set 3
+ i32.const 32
+ local.set 4
+ local.get 3
+ local.get 4
+ i32.sub
+ local.set 5
+ local.get 5
+ local.get 0
+ i32.store 24
+ local.get 5
+ local.get 1
+ i32.store 20
+ local.get 2
+ local.set 6
+ local.get 5
+ local.get 6
+ i32.store8 19
+.Ltmp0:
+ .loc 1 3 7 prologue_end # test.cpp:3:7
+ local.get 5
+ i32.load8_u 19
+ local.set 7
+.Ltmp1:
+ .loc 1 3 7 is_stmt 0 # test.cpp:3:7
+ i32.const 1
+ local.set 8
+ local.get 7
+ local.get 8
+ i32.and
+ local.set 9
+ block
+ block
+ local.get 9
+ i32.eqz
+ br_if 0 # 0: down to label1
+# %bb.1: # %if.then
+.Ltmp2:
+ .loc 1 5 19 is_stmt 1 # test.cpp:5:19
+ i32.const 7
+ local.set 10
+ local.get 5
+ local.get 10
+ i32.store 12
+ .loc 1 6 5 # test.cpp:6:5
+ i32.const 7
+ local.set 11
+ local.get 5
+ local.get 11
+ i32.store 28
+ br 1 # 1: down to label0
+.Ltmp3:
+.LBB0_2: # %if.end
+ .loc 1 0 5 is_stmt 0 # test.cpp:0:5
+ end_block # label1:
+ .loc 1 8 10 is_stmt 1 # test.cpp:8:10
+ local.get 5
+ i32.load 20
+ local.set 12
+ .loc 1 8 3 is_stmt 0 # test.cpp:8:3
+ local.get 5
+ local.get 12
+ i32.store 28
+.LBB0_3: # %return
+ .loc 1 0 3 # test.cpp:0:3
+ end_block # label0:
+ .loc 1 9 1 is_stmt 1 # test.cpp:9:1
+ local.get 5
+ i32.load 28
+ local.set 13
+ local.get 13
+ return
+ end_function
+.Ltmp4:
+.Lfunc_end0:
+ # -- End function
+ .section .debug_abbrev,"",@
+ .int8 1 # Abbreviation Code
+ .int8 17 # DW_TAG_compile_unit
+ .int8 1 # DW_CHILDREN_yes
+ .int8 37 # DW_AT_producer
+ .int8 14 # DW_FORM_strp
+ .int8 19 # DW_AT_language
+ .int8 5 # DW_FORM_data2
+ .int8 3 # DW_AT_name
+ .int8 14 # DW_FORM_strp
+ .int8 16 # DW_AT_stmt_list
+ .int8 23 # DW_FORM_sec_offset
+ .int8 27 # DW_AT_comp_dir
+ .int8 14 # DW_FORM_strp
+ .int8 17 # DW_AT_low_pc
+ .int8 1 # DW_FORM_addr
+ .int8 18 # DW_AT_high_pc
+ .int8 6 # DW_FORM_data4
+ .int8 0 # EOM(1)
+ .int8 0 # EOM(2)
+ .int8 2 # Abbreviation Code
+ .int8 46 # DW_TAG_subprogram
+ .int8 1 # DW_CHILDREN_yes
+ .int8 17 # DW_AT_low_pc
+ .int8 1 # DW_FORM_addr
+ .int8 18 # DW_AT_high_pc
+ .int8 6 # DW_FORM_data4
+ .int8 64 # DW_AT_frame_base
+ .int8 24 # DW_FORM_exprloc
+ .int8 110 # DW_AT_linkage_name
+ .int8 14 # DW_FORM_strp
+ .int8 3 # DW_AT_name
+ .int8 14 # DW_FORM_strp
+ .int8 58 # DW_AT_decl_file
+ .int8 11 # DW_FORM_data1
+ .int8 59 # DW_AT_decl_line
+ .int8 11 # DW_FORM_data1
+ .int8 73 # DW_AT_type
+ .int8 19 # DW_FORM_ref4
+ .int8 63 # DW_AT_external
+ .int8 25 # DW_FORM_flag_present
+ .int8 0 # EOM(1)
+ .int8 0 # EOM(2)
+ .int8 3 # Abbreviation Code
+ .int8 5 # DW_TAG_formal_parameter
+ .int8 0 # DW_CHILDREN_no
+ .int8 2 # DW_AT_location
+ .int8 24 # DW_FORM_exprloc
+ .int8 3 # DW_AT_name
+ .int8 14 # DW_FORM_strp
+ .int8 58 # DW_AT_decl_file
+ .int8 11 # DW_FORM_data1
+ .int8 59 # DW_AT_decl_line
+ .int8 11 # DW_FORM_data1
+ .int8 73 # DW_AT_type
+ .int8 19 # DW_FORM_ref4
+ .int8 0 # EOM(1)
+ .int8 0 # EOM(2)
+ .int8 4 # Abbreviation Code
+ .int8 11 # DW_TAG_lexical_block
+ .int8 1 # DW_CHILDREN_yes
+ .int8 17 # DW_AT_low_pc
+ .int8 1 # DW_FORM_addr
+ .int8 18 # DW_AT_high_pc
+ .int8 6 # DW_FORM_data4
+ .int8 0 # EOM(1)
+ .int8 0 # EOM(2)
+ .int8 5 # Abbreviation Code
+ .int8 52 # DW_TAG_variable
+ .int8 0 # DW_CHILDREN_no
+ .int8 2 # DW_AT_location
+ .int8 24 # DW_FORM_exprloc
+ .int8 3 # DW_AT_name
+ .int8 14 # DW_FORM_strp
+ .int8 58 # DW_AT_decl_file
+ .int8 11 # DW_FORM_data1
+ .int8 59 # DW_AT_decl_line
+ .int8 11 # DW_FORM_data1
+ .int8 73 # DW_AT_type
+ .int8 19 # DW_FORM_ref4
+ .int8 0 # EOM(1)
+ .int8 0 # EOM(2)
+ .int8 6 # Abbreviation Code
+ .int8 22 # DW_TAG_typedef
+ .int8 0 # DW_CHILDREN_no
+ .int8 73 # DW_AT_type
+ .int8 19 # DW_FORM_ref4
+ .int8 3 # DW_AT_name
+ .int8 14 # DW_FORM_strp
+ .int8 58 # DW_AT_decl_file
+ .int8 11 # DW_FORM_data1
+ .int8 59 # DW_AT_decl_line
+ .int8 11 # DW_FORM_data1
+ .int8 0 # EOM(1)
+ .int8 0 # EOM(2)
+ .int8 7 # Abbreviation Code
+ .int8 36 # DW_TAG_base_type
+ .int8 0 # DW_CHILDREN_no
+ .int8 3 # DW_AT_name
+ .int8 14 # DW_FORM_strp
+ .int8 62 # DW_AT_encoding
+ .int8 11 # DW_FORM_data1
+ .int8 11 # DW_AT_byte_size
+ .int8 11 # DW_FORM_data1
+ .int8 0 # EOM(1)
+ .int8 0 # EOM(2)
+ .int8 8 # Abbreviation Code
+ .int8 15 # DW_TAG_pointer_type
+ .int8 0 # DW_CHILDREN_no
+ .int8 73 # DW_AT_type
+ .int8 19 # DW_FORM_ref4
+ .int8 0 # EOM(1)
+ .int8 0 # EOM(2)
+ .int8 9 # Abbreviation Code
+ .int8 38 # DW_TAG_const_type
+ .int8 0 # DW_CHILDREN_no
+ .int8 73 # DW_AT_type
+ .int8 19 # DW_FORM_ref4
+ .int8 0 # EOM(1)
+ .int8 0 # EOM(2)
+ .int8 0 # EOM(3)
+ .section .debug_info,"",@
+.Lcu_begin0:
+ .int32 .Ldebug_info_end0-.Ldebug_info_start0 # Length of Unit
+.Ldebug_info_start0:
+ .int16 4 # DWARF version number
+ .int32 .debug_abbrev0 # Offset Into Abbrev. Section
+ .int8 4 # Address Size (in bytes)
+ .int8 1 # Abbrev [1] 0xb:0xb5 DW_TAG_compile_unit
+ .int32 .Linfo_string0 # DW_AT_producer
+ .int16 33 # DW_AT_language
+ .int32 .Linfo_string1 # DW_AT_name
+ .int32 .Lline_table_start0 # DW_AT_stmt_list
+ .int32 .Linfo_string2 # DW_AT_comp_dir
+ .int32 .Lfunc_begin0 # DW_AT_low_pc
+ .int32 .Lfunc_end0-.Lfunc_begin0 # DW_AT_high_pc
+ .int8 2 # Abbrev [2] 0x26:0x6a DW_TAG_subprogram
+ .int32 0xffffffff # DW_AT_low_pc
+ .int32 .Lfunc_end0-.Lfunc_begin0 # DW_AT_high_pc
+ .int8 4 # DW_AT_frame_base
+ .int8 237
+ .int8 0
+ .int8 5
+ .int8 159
+ .int32 .Linfo_string3 # DW_AT_linkage_name
+ .int32 .Linfo_string4 # DW_AT_name
+ .int8 1 # DW_AT_decl_file
+ .int8 2 # DW_AT_decl_line
+ .int32 144 # DW_AT_type
+ # DW_AT_external
+ .int8 3 # Abbrev [3] 0x42:0xe DW_TAG_formal_parameter
+ .int8 2 # DW_AT_location
+ .int8 145
+ .int8 24
+ .int32 .Linfo_string6 # DW_AT_name
+ .int8 1 # DW_AT_decl_file
+ .int8 2 # DW_AT_decl_line
+ .int32 151 # DW_AT_type
+ .int8 3 # Abbrev [3] 0x50:0xe DW_TAG_formal_parameter
+ .int8 2 # DW_AT_location
+ .int8 145
+ .int8 20
+ .int32 .Linfo_string8 # DW_AT_name
+ .int8 1 # DW_AT_decl_file
+ .int8 2 # DW_AT_decl_line
+ .int32 172 # DW_AT_type
+ .int8 3 # Abbrev [3] 0x5e:0xe DW_TAG_formal_parameter
+ .int8 2 # DW_AT_location
+ .int8 145
+ .int8 19
+ .int32 .Linfo_string10 # DW_AT_name
+ .int8 1 # DW_AT_decl_file
+ .int8 2 # DW_AT_decl_line
+ .int32 179 # DW_AT_type
+ .int8 4 # Abbrev [4] 0x6c:0x18 DW_TAG_lexical_block
+ .int32 .Ltmp2 # DW_AT_low_pc
+ .int32 .Ltmp3-.Ltmp2 # DW_AT_high_pc
+ .int8 5 # Abbrev [5] 0x75:0xe DW_TAG_variable
+ .int8 2 # DW_AT_location
+ .int8 145
+ .int8 12
+ .int32 .Linfo_string12 # DW_AT_name
+ .int8 1 # DW_AT_decl_file
+ .int8 5 # DW_AT_decl_line
+ .int32 186 # DW_AT_type
+ .int8 0 # End Of Children Mark
+ .int8 6 # Abbrev [6] 0x84:0xb DW_TAG_typedef
+ .int32 144 # DW_AT_type
+ .int32 .Linfo_string13 # DW_AT_name
+ .int8 1 # DW_AT_decl_file
+ .int8 4 # DW_AT_decl_line
+ .int8 0 # End Of Children Mark
+ .int8 7 # Abbrev [7] 0x90:0x7 DW_TAG_base_type
+ .int32 .Linfo_string5 # DW_AT_name
+ .int8 5 # DW_AT_encoding
+ .int8 4 # DW_AT_byte_size
+ .int8 6 # Abbrev [6] 0x97:0xb DW_TAG_typedef
+ .int32 162 # DW_AT_type
+ .int32 .Linfo_string7 # DW_AT_name
+ .int8 1 # DW_AT_decl_file
+ .int8 1 # DW_AT_decl_line
+ .int8 8 # Abbrev [8] 0xa2:0x5 DW_TAG_pointer_type
+ .int32 167 # DW_AT_type
+ .int8 9 # Abbrev [9] 0xa7:0x5 DW_TAG_const_type
+ .int32 144 # DW_AT_type
+ .int8 7 # Abbrev [7] 0xac:0x7 DW_TAG_base_type
+ .int32 .Linfo_string9 # DW_AT_name
+ .int8 7 # DW_AT_encoding
+ .int8 4 # DW_AT_byte_size
+ .int8 7 # Abbrev [7] 0xb3:0x7 DW_TAG_base_type
+ .int32 .Linfo_string11 # DW_AT_name
+ .int8 2 # DW_AT_encoding
+ .int8 1 # DW_AT_byte_size
+ .int8 9 # Abbrev [9] 0xba:0x5 DW_TAG_const_type
+ .int32 132 # DW_AT_type
+ .int8 0 # End Of Children Mark
+.Ldebug_info_end0:
+ .section .debug_str,"S",@
+.Linfo_string0:
+ .asciz "clang version 19.0.0" # string offset=0
+.Linfo_string1:
+ .asciz "test.cpp" # string offset=111
+.Linfo_string2:
+ .asciz "general" # string offset=120
+.Linfo_string3:
+ .asciz "_Z3fooPKijb" # string offset=174
+.Linfo_string4:
+ .asciz "foo" # string offset=186
+.Linfo_string5:
+ .asciz "int" # string offset=190
+.Linfo_string6:
+ .asciz "ParamPtr" # string offset=194
+.Linfo_string7:
+ .asciz "INTPTR" # string offset=203
+.Linfo_string8:
+ .asciz "ParamUnsigned" # string offset=210
+.Linfo_string9:
+ .asciz "unsigned int" # strin...
[truncated]
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✅ With the latest revision this PR passed the C/C++ code formatter. |
llvm#136772 Incorrect handling of 'tombstone' value for WebAssembly. Fix clang-format issue.
dwblaikie
reviewed
May 27, 2025
Comment on lines
136
to
138
| // Tombstone value. Assume 64 bits. The value is updated for each | ||
| // Compile Unit that is processed. | ||
| LVAddress TombstoneAddress = MaxAddress; |
There was a problem hiding this comment.
If the value's updated for each CU anyway, could we leave it uninitialized here? (or set it to some meta-tombstone address, so we can assert that value isn't present when we expect a real tombstone value from the CU?)
There was a problem hiding this comment.
Checking for a valid (real) tombstone value it is a good idea.
With this patch, we use '-1' for both 32 and 64 bits.
Looking at these DWARF accepted changes:
https://dwarfstd.org/issues/231013.1.html
https://dwarfstd.org/issues/200609.1.html
What would be some meta-tombstone address that is not a real one, but that we can identify as check-marker? May be the -2 value?
| @@ -0,0 +1,44 @@ | |||
| ; REQUIRES: x86-registered-target | |||
There was a problem hiding this comment.
Do we usually split out the test and .s file in these tests? Most other tests in the LLVM project keep the content in the same file where possible.
(& some comments describing what the assembly is from/what it describes might be handy too, either here (if everything can be merged), or in the assembly file (if it can't be merged))
There was a problem hiding this comment.
Do we usually split out the test and .s file in these tests? Most other tests in the LLVM project keep the content in the same file where possible.
I just followed the same approach as for the existing .s files. I don't mind to combine the test and .s file.
(& some comments describing what the assembly is from/what it describes might be handy too, either here (if everything can be merged), or in the assembly file (if it can't be merged))
I will update the comments and combine the test with the .s file.
|
Confirming that this fixes my original reproducer from #136772. Thanks! 🙂 |
llvm#136772 Incorrect handling of 'tombstone' value for WebAssembly. Address comments from reviewers: - Combine test and .s file. - Introduce the concept of a meta-tombstone value, to be able to check for an invalid tombstone value.
|
Uploaded a new patch:
|
llvm#136772 Incorrect handling of 'tombstone' value for WebAssembly. Minor comments change in test case.
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#136772
Incorrect handling of 'tombstone' value for WebAssembly.
llvm-debuginfo-analyzer already uses the tombstone approach
to identify dead code. Currently, the tombstone value is
evaluated as std::numeric_limits<uint64_t>::max(). Which is
wrong as it does not take into account the 'Address Byte Size'
from the Compile Unit header.