shafik created this revision.
shafik added reviewers: aprantl, friss, labath, jingham, vsk.
shafik requested review of this revision.
Herald added a reviewer: jdoerfert.
Herald added a subscriber: sstefan1.
In some cases when we have a `DW_AT_const_value` and the data can be found in
the `DWARFExpression` then `ValueObjectVariable` does not handle it properly
and we end up with an `extracting data from value failed` error:
(lldb) target var constant
(U) constant = {
raw = <extracting data from value failed>
= (a = <extracting data from value failed>, b = <extracting data from
value failed>, c = <extracting data from value failed>, d = <extracting data
from value failed>, e = <extracting data from value failed>, f = <extracting
data from value failed>)
}
This should fix that case.
The test is a very stripped down assembly file since reproducing this relies on
the results of compiling with `-O1` which may not be stable over time.
https://reviews.llvm.org/D86311
Files:
lldb/source/Core/ValueObjectVariable.cpp
lldb/test/Shell/SymbolFile/DWARF/DW_AT_const_value.s
Index: lldb/test/Shell/SymbolFile/DWARF/DW_AT_const_value.s
===================================================================
--- /dev/null
+++ lldb/test/Shell/SymbolFile/DWARF/DW_AT_const_value.s
@@ -0,0 +1,408 @@
+# RUN: llvm-mc -filetype=obj -o %t -triple x86_64-apple-macosx10.15.0 %s
+# RUN: %lldb %t -o "target variable constant" -b | FileCheck %s
+
+# CHECK: (lldb) target variable constant
+# CHECK: (U) constant = {
+# CHECK: raw = 1688469761
+# CHECK: = (a = 1, b = 1, c = 36, d = 2, e = 36, f = 1)
+# CHECK: }
+
+# This is testing when how ValueObjectVariable handles the case where the
+# DWARFExpression holds the data that represents a constant value.
+# Compile at -O1 allows us to capture this case. Below is the code used
+# to generate the assembly:
+#
+# typedef union
+# {
+# unsigned raw;
+# struct
+# {
+# unsigned a : 8;
+# unsigned b : 8;
+# unsigned c : 6;
+# unsigned d : 2;
+# unsigned e : 6;
+# unsigned f : 2;
+# } ;
+# } U;
+#
+# static U __attribute__((used)) _type_anchor;
+# static const int constant = 0x64A40101;
+#
+# int g() { return constant; }
+#
+# int main() {
+# U u;
+# u.raw = 0x64A40101;
+# }
+#
+# Compiled as follows:
+#
+# clang -gdwarf-4 -O1 dw_at_const_value_bug.c -S -o dw_at_const_value_bug.s
+#
+# I was able to obtain a global of type U with DW_AT_const_value but was able
+# to using int. This required modifying the DW_AT_type of constant to be type
+# U. After that stripping as much of the assembly as possible to give us a
+# smaller reproducer.
+
+
+.zerofill __DATA,__bss,__type_anchor,4,2 ## @_type_anchor
+ .no_dead_strip __type_anchor
+ .section __DWARF,__debug_str,regular,debug
+Linfo_string:
+ .zero 90
+ .asciz "constant" ## string offset=90
+ .asciz "int" ## string offset=99
+ .asciz "_type_anchor" ## string offset=103
+ .asciz "U" ## string offset=116
+ .asciz "raw" ## string offset=118
+ .asciz "unsigned int" ## string offset=122
+ .asciz "a" ## string offset=135
+ .asciz "b" ## string offset=137
+ .asciz "c" ## string offset=139
+ .asciz "d" ## string offset=141
+ .asciz "e" ## string offset=143
+ .asciz "f" ## string offset=145
+ .asciz "g" ## string offset=147
+ .asciz "main" ## string offset=149
+ .asciz "u" ## string offset=154
+ .section __DWARF,__debug_abbrev,regular,debug
+Lsection_abbrev:
+ .byte 1 ## Abbreviation Code
+ .byte 17 ## DW_TAG_compile_unit
+ .byte 1 ## DW_CHILDREN_yes
+ .byte 37 ## DW_AT_producer
+ .byte 14 ## DW_FORM_strp
+ .byte 19 ## DW_AT_language
+ .byte 5 ## DW_FORM_data2
+ .byte 3 ## DW_AT_name
+ .byte 14 ## DW_FORM_strp
+ .byte 66 ## DW_AT_stmt_list
+ .byte 23 ## DW_FORM_sec_offset
+ .byte 27 ## DW_AT_comp_dir
+ .byte 14 ## DW_FORM_strp
+ .ascii "\264B" ## DW_AT_GNU_pubnames
+ .byte 25 ## DW_FORM_flag_present
+ .ascii "\341\177" ## DW_AT_APPLE_optimized
+ .byte 25 ## DW_FORM_flag_present
+ .byte 17 ## DW_AT_low_pc
+ .byte 1 ## DW_FORM_addr
+ .byte 18 ## DW_AT_high_pc
+ .byte 6 ## DW_FORM_data4
+ .byte 0 ## EOM(1)
+ .byte 0 ## EOM(2)
+ .byte 2 ## Abbreviation Code
+ .byte 52 ## DW_TAG_variable
+ .byte 0 ## DW_CHILDREN_no
+ .byte 3 ## DW_AT_name
+ .byte 14 ## DW_FORM_strp
+ .byte 73 ## DW_AT_type
+ .byte 19 ## DW_FORM_ref4
+ .byte 58 ## DW_AT_decl_file
+ .byte 11 ## DW_FORM_data1
+ .byte 59 ## DW_AT_decl_line
+ .byte 11 ## DW_FORM_data1
+ .byte 28 ## DW_AT_const_value
+ .byte 15 ## DW_FORM_udata
+ .byte 0 ## EOM(1)
+ .byte 0 ## EOM(2)
+ .byte 3 ## Abbreviation Code
+ .byte 38 ## DW_TAG_const_type
+ .byte 0 ## DW_CHILDREN_no
+ .byte 73 ## DW_AT_type
+ .byte 19 ## DW_FORM_ref4
+ .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 14 ## DW_FORM_strp
+ .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 5 ## Abbreviation Code
+ .byte 52 ## DW_TAG_variable
+ .byte 0 ## DW_CHILDREN_no
+ .byte 3 ## DW_AT_name
+ .byte 14 ## DW_FORM_strp
+ .byte 73 ## DW_AT_type
+ .byte 19 ## DW_FORM_ref4
+ .byte 58 ## DW_AT_decl_file
+ .byte 11 ## DW_FORM_data1
+ .byte 59 ## DW_AT_decl_line
+ .byte 11 ## DW_FORM_data1
+ .byte 2 ## DW_AT_location
+ .byte 24 ## DW_FORM_exprloc
+ .byte 0 ## EOM(1)
+ .byte 0 ## EOM(2)
+ .byte 6 ## Abbreviation Code
+ .byte 22 ## DW_TAG_typedef
+ .byte 0 ## DW_CHILDREN_no
+ .byte 73 ## DW_AT_type
+ .byte 19 ## DW_FORM_ref4
+ .byte 3 ## DW_AT_name
+ .byte 14 ## DW_FORM_strp
+ .byte 58 ## DW_AT_decl_file
+ .byte 11 ## DW_FORM_data1
+ .byte 59 ## DW_AT_decl_line
+ .byte 11 ## DW_FORM_data1
+ .byte 0 ## EOM(1)
+ .byte 0 ## EOM(2)
+ .byte 7 ## Abbreviation Code
+ .byte 23 ## DW_TAG_union_type
+ .byte 1 ## DW_CHILDREN_yes
+ .byte 11 ## DW_AT_byte_size
+ .byte 11 ## DW_FORM_data1
+ .byte 58 ## DW_AT_decl_file
+ .byte 11 ## DW_FORM_data1
+ .byte 59 ## DW_AT_decl_line
+ .byte 11 ## DW_FORM_data1
+ .byte 0 ## EOM(1)
+ .byte 0 ## EOM(2)
+ .byte 8 ## Abbreviation Code
+ .byte 13 ## DW_TAG_member
+ .byte 0 ## DW_CHILDREN_no
+ .byte 3 ## DW_AT_name
+ .byte 14 ## DW_FORM_strp
+ .byte 73 ## DW_AT_type
+ .byte 19 ## DW_FORM_ref4
+ .byte 58 ## DW_AT_decl_file
+ .byte 11 ## DW_FORM_data1
+ .byte 59 ## DW_AT_decl_line
+ .byte 11 ## DW_FORM_data1
+ .byte 56 ## DW_AT_data_member_location
+ .byte 11 ## DW_FORM_data1
+ .byte 0 ## EOM(1)
+ .byte 0 ## EOM(2)
+ .byte 9 ## Abbreviation Code
+ .byte 13 ## DW_TAG_member
+ .byte 0 ## DW_CHILDREN_no
+ .byte 73 ## DW_AT_type
+ .byte 19 ## DW_FORM_ref4
+ .byte 58 ## DW_AT_decl_file
+ .byte 11 ## DW_FORM_data1
+ .byte 59 ## DW_AT_decl_line
+ .byte 11 ## DW_FORM_data1
+ .byte 56 ## DW_AT_data_member_location
+ .byte 11 ## DW_FORM_data1
+ .byte 0 ## EOM(1)
+ .byte 0 ## EOM(2)
+ .byte 10 ## Abbreviation Code
+ .byte 19 ## DW_TAG_structure_type
+ .byte 1 ## DW_CHILDREN_yes
+ .byte 11 ## DW_AT_byte_size
+ .byte 11 ## DW_FORM_data1
+ .byte 58 ## DW_AT_decl_file
+ .byte 11 ## DW_FORM_data1
+ .byte 59 ## DW_AT_decl_line
+ .byte 11 ## DW_FORM_data1
+ .byte 0 ## EOM(1)
+ .byte 0 ## EOM(2)
+ .byte 11 ## Abbreviation Code
+ .byte 13 ## DW_TAG_member
+ .byte 0 ## DW_CHILDREN_no
+ .byte 3 ## DW_AT_name
+ .byte 14 ## DW_FORM_strp
+ .byte 73 ## DW_AT_type
+ .byte 19 ## DW_FORM_ref4
+ .byte 58 ## DW_AT_decl_file
+ .byte 11 ## DW_FORM_data1
+ .byte 59 ## DW_AT_decl_line
+ .byte 11 ## DW_FORM_data1
+ .byte 13 ## DW_AT_bit_size
+ .byte 11 ## DW_FORM_data1
+ .byte 107 ## DW_AT_data_bit_offset
+ .byte 11 ## DW_FORM_data1
+ .byte 0 ## EOM(1)
+ .byte 0 ## EOM(2)
+ .byte 12 ## Abbreviation Code
+ .byte 46 ## DW_TAG_subprogram
+ .byte 0 ## DW_CHILDREN_no
+ .byte 17 ## DW_AT_low_pc
+ .byte 1 ## DW_FORM_addr
+ .byte 18 ## DW_AT_high_pc
+ .byte 6 ## DW_FORM_data4
+ .byte 64 ## DW_AT_frame_base
+ .byte 24 ## DW_FORM_exprloc
+ .byte 122 ## DW_AT_call_all_calls
+ .byte 25 ## DW_FORM_flag_present
+ .byte 3 ## DW_AT_name
+ .byte 14 ## DW_FORM_strp
+ .byte 58 ## DW_AT_decl_file
+ .byte 11 ## DW_FORM_data1
+ .byte 59 ## DW_AT_decl_line
+ .byte 11 ## DW_FORM_data1
+ .byte 73 ## DW_AT_type
+ .byte 19 ## DW_FORM_ref4
+ .byte 63 ## DW_AT_external
+ .byte 25 ## DW_FORM_flag_present
+ .ascii "\341\177" ## DW_AT_APPLE_optimized
+ .byte 25 ## DW_FORM_flag_present
+ .byte 0 ## EOM(1)
+ .byte 0 ## EOM(2)
+ .byte 13 ## Abbreviation Code
+ .byte 46 ## DW_TAG_subprogram
+ .byte 1 ## DW_CHILDREN_yes
+ .byte 17 ## DW_AT_low_pc
+ .byte 1 ## DW_FORM_addr
+ .byte 18 ## DW_AT_high_pc
+ .byte 6 ## DW_FORM_data4
+ .byte 64 ## DW_AT_frame_base
+ .byte 24 ## DW_FORM_exprloc
+ .byte 122 ## DW_AT_call_all_calls
+ .byte 25 ## DW_FORM_flag_present
+ .byte 3 ## DW_AT_name
+ .byte 14 ## DW_FORM_strp
+ .byte 58 ## DW_AT_decl_file
+ .byte 11 ## DW_FORM_data1
+ .byte 59 ## DW_AT_decl_line
+ .byte 11 ## DW_FORM_data1
+ .byte 73 ## DW_AT_type
+ .byte 19 ## DW_FORM_ref4
+ .byte 63 ## DW_AT_external
+ .byte 25 ## DW_FORM_flag_present
+ .ascii "\341\177" ## DW_AT_APPLE_optimized
+ .byte 25 ## DW_FORM_flag_present
+ .byte 0 ## EOM(1)
+ .byte 0 ## EOM(2)
+ .byte 14 ## Abbreviation Code
+ .byte 52 ## DW_TAG_variable
+ .byte 0 ## DW_CHILDREN_no
+ .byte 28 ## DW_AT_const_value
+ .byte 15 ## DW_FORM_udata
+ .byte 3 ## DW_AT_name
+ .byte 14 ## DW_FORM_strp
+ .byte 58 ## DW_AT_decl_file
+ .byte 11 ## DW_FORM_data1
+ .byte 59 ## DW_AT_decl_line
+ .byte 11 ## DW_FORM_data1
+ .byte 73 ## DW_AT_type
+ .byte 19 ## DW_FORM_ref4
+ .byte 0 ## EOM(1)
+ .byte 0 ## EOM(2)
+ .byte 0 ## EOM(3)
+ .section __DWARF,__debug_info,regular,debug
+Lsection_info:
+Lcu_begin0:
+.set Lset0, Ldebug_info_end0-Ldebug_info_start0 ## Length of Unit
+ .long Lset0
+Ldebug_info_start0:
+ .short 4 ## DWARF version number
+.set Lset1, Lsection_abbrev-Lsection_abbrev ## Offset Into Abbrev. Section
+ .long Lset1
+ .byte 8 ## Address Size (in bytes)
+ .byte 1 ## Abbrev [1] 0xb:0x112 DW_TAG_compile_unit
+ .long 0 ## DW_AT_producer
+ .short 12 ## DW_AT_language
+ .long 47 ## DW_AT_name
+ .long 0 ## DW_AT_stmt_list
+ .long 71 ## DW_AT_comp_dir
+ ## DW_AT_GNU_pubnames
+ ## DW_AT_APPLE_optimized
+ .quad 0 ## DW_AT_low_pc
+ .long 0
+ .byte 2 ## Abbrev [2] 0x2a:0x10 DW_TAG_variable
+ .long 90 ## DW_AT_name
+ .long 91 ## DW_AT_type
+ .byte 1 ## DW_AT_decl_file
+ .byte 16 ## DW_AT_decl_line
+ .ascii "\201\202\220\245\006" ## DW_AT_const_value
+ .byte 3 ## Abbrev [3] 0x3a:0x5 DW_TAG_const_type
+ .long 63 ## DW_AT_type
+ .byte 4 ## Abbrev [4] 0x3f:0x7 DW_TAG_base_type
+ .long 99 ## DW_AT_name
+ .byte 5 ## DW_AT_encoding
+ .byte 4 ## DW_AT_byte_size
+ .byte 5 ## Abbrev [5] 0x46:0x15 DW_TAG_variable
+ .long 103 ## DW_AT_name
+ .long 91 ## DW_AT_type
+ .byte 1 ## DW_AT_decl_file
+ .byte 15 ## DW_AT_decl_line
+ .byte 9 ## DW_AT_location
+ .byte 3
+ .quad __type_anchor
+ .byte 6 ## Abbrev [6] 0x5b:0xb DW_TAG_typedef
+ .long 102 ## DW_AT_type
+ .long 116 ## DW_AT_name
+ .byte 1 ## DW_AT_decl_file
+ .byte 13 ## DW_AT_decl_line
+ .byte 7 ## Abbrev [7] 0x66:0x6c DW_TAG_union_type
+ .byte 4 ## DW_AT_byte_size
+ .byte 1 ## DW_AT_decl_file
+ .byte 1 ## DW_AT_decl_line
+ .byte 8 ## Abbrev [8] 0x6a:0xc DW_TAG_member
+ .long 118 ## DW_AT_name
+ .long 210 ## DW_AT_type
+ .byte 1 ## DW_AT_decl_file
+ .byte 3 ## DW_AT_decl_line
+ .byte 0 ## DW_AT_data_member_location
+ .byte 9 ## Abbrev [9] 0x76:0x8 DW_TAG_member
+ .long 126 ## DW_AT_type
+ .byte 1 ## DW_AT_decl_file
+ .byte 4 ## DW_AT_decl_line
+ .byte 0 ## DW_AT_data_member_location
+ .byte 10 ## Abbrev [10] 0x7e:0x53 DW_TAG_structure_type
+ .byte 4 ## DW_AT_byte_size
+ .byte 1 ## DW_AT_decl_file
+ .byte 4 ## DW_AT_decl_line
+ .byte 11 ## Abbrev [11] 0x82:0xd DW_TAG_member
+ .long 135 ## DW_AT_name
+ .long 210 ## DW_AT_type
+ .byte 1 ## DW_AT_decl_file
+ .byte 6 ## DW_AT_decl_line
+ .byte 8 ## DW_AT_bit_size
+ .byte 0 ## DW_AT_data_bit_offset
+ .byte 11 ## Abbrev [11] 0x8f:0xd DW_TAG_member
+ .long 137 ## DW_AT_name
+ .long 210 ## DW_AT_type
+ .byte 1 ## DW_AT_decl_file
+ .byte 7 ## DW_AT_decl_line
+ .byte 8 ## DW_AT_bit_size
+ .byte 8 ## DW_AT_data_bit_offset
+ .byte 11 ## Abbrev [11] 0x9c:0xd DW_TAG_member
+ .long 139 ## DW_AT_name
+ .long 210 ## DW_AT_type
+ .byte 1 ## DW_AT_decl_file
+ .byte 8 ## DW_AT_decl_line
+ .byte 6 ## DW_AT_bit_size
+ .byte 16 ## DW_AT_data_bit_offset
+ .byte 11 ## Abbrev [11] 0xa9:0xd DW_TAG_member
+ .long 141 ## DW_AT_name
+ .long 210 ## DW_AT_type
+ .byte 1 ## DW_AT_decl_file
+ .byte 9 ## DW_AT_decl_line
+ .byte 2 ## DW_AT_bit_size
+ .byte 22 ## DW_AT_data_bit_offset
+ .byte 11 ## Abbrev [11] 0xb6:0xd DW_TAG_member
+ .long 143 ## DW_AT_name
+ .long 210 ## DW_AT_type
+ .byte 1 ## DW_AT_decl_file
+ .byte 10 ## DW_AT_decl_line
+ .byte 6 ## DW_AT_bit_size
+ .byte 24 ## DW_AT_data_bit_offset
+ .byte 11 ## Abbrev [11] 0xc3:0xd DW_TAG_member
+ .long 145 ## DW_AT_name
+ .long 210 ## DW_AT_type
+ .byte 1 ## DW_AT_decl_file
+ .byte 11 ## DW_AT_decl_line
+ .byte 2 ## DW_AT_bit_size
+ .byte 30 ## DW_AT_data_bit_offset
+ .byte 0 ## End Of Children Mark
+ .byte 0 ## End Of Children Mark
+ .byte 4 ## Abbrev [4] 0xd2:0x7 DW_TAG_base_type
+ .long 122 ## DW_AT_name
+ .byte 7 ## DW_AT_encoding
+ .byte 4 ## DW_AT_byte_size
+ .byte 14 ## Abbrev [14] 0x10b:0x10 DW_TAG_variable
+ .ascii "\201\202\220\245\006" ## DW_AT_const_value
+ .long 154 ## DW_AT_name
+ .byte 1 ## DW_AT_decl_file
+ .byte 21 ## DW_AT_decl_line
+ .long 91 ## DW_AT_type
+ .byte 0 ## End Of Children Mark
+ .byte 0 ## End Of Children Mark
+Ldebug_info_end0:
Index: lldb/source/Core/ValueObjectVariable.cpp
===================================================================
--- lldb/source/Core/ValueObjectVariable.cpp
+++ lldb/source/Core/ValueObjectVariable.cpp
@@ -132,8 +132,11 @@
if (variable->GetLocationIsConstantValueData()) {
// expr doesn't contain DWARF bytes, it contains the constant variable
// value bytes themselves...
- if (expr.GetExpressionData(m_data))
+ if (expr.GetExpressionData(m_data)) {
+ if (m_data.GetDataStart() && m_data.GetByteSize())
+ m_value.SetBytes(m_data.GetDataStart(), m_data.GetByteSize());
m_value.SetContext(Value::eContextTypeVariable, variable);
+ }
else
m_error.SetErrorString("empty constant data");
// constant bytes can't be edited - sorry
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