labath created this revision.
labath added reviewers: shafik, aprantl.
Herald added a project: LLDB.
labath requested review of this revision.
Herald added a reviewer: jdoerfert.
Herald added subscribers: sstefan1, JDevlieghere.

This fixes several issues in handling of DW_AT_const_value attributes:

- the first is that the size of the data given by data forms does not need to 
match the size of the underlying variable. We already had the case to handle 
this for DW_FORM_(us)data -- this extends the handling to other data forms. The 
main reason this was not picked up is because clang uses leb forms in these 
cases while gcc prefers the fixed-size ones.
- The handling of DW_AT_strp form was completely broken -- we would end up 
using the pointer value as the result. I've reorganized this code so that it 
handles all string forms uniformly.
- In case of a completely bogus form we would crash due to strlen(nullptr).

Depends on D86311 <https://reviews.llvm.org/D86311>.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D86348

Files:
  lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
  lldb/test/Shell/SymbolFile/DWARF/DW_AT_const_value.s

Index: lldb/test/Shell/SymbolFile/DWARF/DW_AT_const_value.s
===================================================================
--- lldb/test/Shell/SymbolFile/DWARF/DW_AT_const_value.s
+++ lldb/test/Shell/SymbolFile/DWARF/DW_AT_const_value.s
@@ -1,408 +1,158 @@
-# 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
+# Test handling of (optimized-out/location-less) variables whose value is
+# specified by DW_AT_const_value
 
-# 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: }
+# REQUIRES: x86
 
-# 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.
+# RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux %s -o %t
+# RUN: %lldb %t \
+# RUN:   -o "target variable udata data1 data2 data4 data8 string strp ref4" \
+# RUN:   -o exit | FileCheck %s
 
+# CHECK-LABEL: target variable udata data1 data2 data4 data8 string strp ref4
+## Variable specified via DW_FORM_udata. This is typical for clang (10).
+# CHECK: (unsigned long) udata = 4742474247424742
+## Variables specified via fixed-size forms. This is typical for gcc (9).
+# CHECK: (unsigned long) data1 = 47
+# CHECK: (unsigned long) data2 = 4742
+# CHECK: (unsigned long) data4 = 47424742
+# CHECK: (unsigned long) data8 = 4742474247424742
+## Variables specified using string forms. This behavior purely speculative -- I
+## don't know of any compiler that would represent character strings this way.
+# CHECK: (char [7]) string = "string"
+# CHECK: (char [7]) strp = "strp"
+## Bogus attribute form. Let's make sure we don't crash at least.
+# CHECK: (char [7]) ref4 = <empty constant data>
 
-.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:
+        .section        .debug_abbrev,"",@progbits
+        .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   3                       # DW_AT_name
+        .byte   8                       # DW_FORM_string
+        .byte   0                       # EOM(1)
+        .byte   0                       # EOM(2)
+        .byte   4                       # Abbreviation Code
+        .byte   1                       # DW_TAG_array_type
+        .byte   1                       # DW_CHILDREN_yes
+        .byte   73                      # DW_AT_type
+        .byte   19                      # DW_FORM_ref4
+        .byte   0                       # EOM(1)
+        .byte   0                       # EOM(2)
+        .byte   5                       # Abbreviation Code
+        .byte   33                      # DW_TAG_subrange_type
+        .byte   0                       # DW_CHILDREN_no
+        .byte   73                      # DW_AT_type
+        .byte   19                      # DW_FORM_ref4
+        .byte   55                      # DW_AT_count
+        .byte   11                      # DW_FORM_data1
+        .byte   0                       # EOM(1)
+        .byte   0                       # EOM(2)
+        .byte   6                       # Abbreviation Code
+        .byte   36                      # DW_TAG_base_type
+        .byte   0                       # DW_CHILDREN_no
+        .byte   3                       # DW_AT_name
+        .byte   8                       # DW_FORM_string
+        .byte   11                      # DW_AT_byte_size
+        .byte   11                      # DW_FORM_data1
+        .byte   62                      # DW_AT_encoding
+        .byte   11                      # DW_FORM_data1
+        .byte   0                       # EOM(1)
+        .byte   0                       # EOM(2)
+.macro var code, form
+        .byte   \code                   # Abbreviation Code
+        .byte   52                      # DW_TAG_variable
+        .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   28                      # DW_AT_const_value
+        .byte   \form
+        .byte   0                       # EOM(1)
+        .byte   0                       # EOM(2)
+.endm
+        var 10, 0xf                     # DW_FORM_udata
+        var 11, 0xb                     # DW_FORM_data1
+        var 12, 0x5                     # DW_FORM_data2
+        var 13, 0x6                     # DW_FORM_data4
+        var 14, 0x7                     # DW_FORM_data8
+        var 15, 0x8                     # DW_FORM_string
+        var 16, 0xe                     # DW_FORM_strp
+        var 17, 0x13                    # DW_FORM_ref4
+        .byte   0                       # EOM(3)
+        .section        .debug_info,"",@progbits
+.Lcu_begin0:
+        .long   .Ldebug_info_end0-.Ldebug_info_start0 # Length of Unit
+.Ldebug_info_start0:
+        .short  4                       # DWARF version number
+        .long   .debug_abbrev           # Offset Into Abbrev. Section
+        .byte   8                       # Address Size (in bytes)
+        .byte   1                       # Abbrev DW_TAG_compile_unit
+        .asciz  "Hand-written DWARF"    # DW_AT_producer
+        .asciz  "const.c"               # DW_AT_name
+.Lchar_arr:
+        .byte   4                       # Abbrev DW_TAG_array_type
+        .long   .Lchar-.Lcu_begin0      # DW_AT_type
+        .byte   5                       # Abbrev DW_TAG_subrange_type
+        .long   .Lulong-.Lcu_begin0     # DW_AT_type
+        .byte   7                       # DW_AT_count
+        .byte   0                       # End Of Children Mark
+.Lchar:
+        .byte   6                       # Abbrev DW_TAG_base_type
+        .asciz  "char"                  # DW_AT_name
+        .byte   1                       # DW_AT_byte_size
+        .byte   6                       # DW_AT_encoding
+.Lulong:
+        .byte   6                       # Abbrev DW_TAG_base_type
+        .asciz  "unsigned long"         # DW_AT_name
+        .byte   8                       # DW_AT_byte_size
+        .byte   7                       # DW_AT_encoding
+
+        .byte   10                      # Abbrev DW_TAG_variable
+        .asciz  "udata"                 # DW_AT_name
+        .long   .Lulong-.Lcu_begin0     # DW_AT_type
+        .uleb128 4742474247424742       # DW_AT_const_value
+
+        .byte   11                      # Abbrev DW_TAG_variable
+        .asciz  "data1"                 # DW_AT_name
+        .long   .Lulong-.Lcu_begin0     # DW_AT_type
+        .byte   47                      # DW_AT_const_value
+
+        .byte   12                      # Abbrev DW_TAG_variable
+        .asciz  "data2"                 # DW_AT_name
+        .long   .Lulong-.Lcu_begin0     # DW_AT_type
+        .word   4742                    # DW_AT_const_value
+
+        .byte   13                      # Abbrev DW_TAG_variable
+        .asciz  "data4"                 # DW_AT_name
+        .long   .Lulong-.Lcu_begin0     # DW_AT_type
+        .long   47424742                # DW_AT_const_value
+
+        .byte   14                      # Abbrev DW_TAG_variable
+        .asciz  "data8"                 # DW_AT_name
+        .long   .Lulong-.Lcu_begin0     # DW_AT_type
+        .quad   4742474247424742        # DW_AT_const_value
+
+        .byte   15                      # Abbrev DW_TAG_variable
+        .asciz  "string"                # DW_AT_name
+        .long   .Lchar_arr-.Lcu_begin0  # DW_AT_type
+        .asciz  "string"                # DW_AT_const_value
+
+        .byte   16                      # Abbrev DW_TAG_variable
+        .asciz  "strp"                  # DW_AT_name
+        .long   .Lchar_arr-.Lcu_begin0  # DW_AT_type
+        .long   .Lstrp                  # DW_AT_const_value
+
+        .byte   17                      # Abbrev DW_TAG_variable
+        .asciz  "ref4"                  # DW_AT_name
+        .long   .Lchar_arr-.Lcu_begin0  # DW_AT_type
+        .long   .Lulong-.Lcu_begin0     # DW_AT_const_value
+
+        .byte   0                       # End Of Children Mark
+.Ldebug_info_end0:
+
+        .section        .debug_str,"MS",@progbits,1
+.Lstrp:
+        .asciz "strp"
Index: lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
===================================================================
--- lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -3197,44 +3197,18 @@
                     DataExtractor(debug_info_data, block_offset, block_length),
                     die.GetCU());
               } else if (DWARFFormValue::IsDataForm(form_value.Form())) {
-                // Retrieve the value as a data expression.
-                uint32_t data_offset = attributes.DIEOffsetAtIndex(i);
-                if (auto data_length = form_value.GetFixedSize())
-                  location = DWARFExpression(
-                      module,
-                      DataExtractor(debug_info_data, data_offset, *data_length),
-                      die.GetCU());
-                else {
-                  const uint8_t *data_pointer = form_value.BlockData();
-                  if (data_pointer) {
-                    form_value.Unsigned();
-                  } else if (DWARFFormValue::IsDataForm(form_value.Form())) {
-                    // we need to get the byte size of the type later after we
-                    // create the variable
-                    const_value = form_value;
-                  }
-                }
-              } else {
-                // Retrieve the value as a string expression.
-                if (form_value.Form() == DW_FORM_strp) {
-                  uint32_t data_offset = attributes.DIEOffsetAtIndex(i);
-                  if (auto data_length = form_value.GetFixedSize())
-                    location = DWARFExpression(module,
-                                               DataExtractor(debug_info_data,
-                                                             data_offset,
-                                                             *data_length),
-                                               die.GetCU());
-                } else {
-                  const char *str = form_value.AsCString();
-                  uint32_t string_offset =
-                      str - (const char *)debug_info_data.GetDataStart();
-                  uint32_t string_length = strlen(str) + 1;
-                  location = DWARFExpression(module,
-                                             DataExtractor(debug_info_data,
-                                                           string_offset,
-                                                           string_length),
-                                             die.GetCU());
-                }
+                // Constant value size does not have to match the size of the
+                // variable. We will fetch the size of the type after we create
+                // it.
+                const_value = form_value;
+              } else if (const char *str = form_value.AsCString()) {
+                uint32_t string_length = strlen(str) + 1;
+                location = DWARFExpression(
+                    module,
+                    DataExtractor(str, string_length,
+                                  die.GetCU()->GetByteOrder(),
+                                  die.GetCU()->GetAddressByteSize()),
+                    die.GetCU());
               }
             }
             break;
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