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Add handling for DW_LNS_set_epilogue_begin in wasm debug info #8414

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Merged
kripken merged 1 commit into from
Mar 5, 2026
Merged

Add handling for DW_LNS_set_epilogue_begin in wasm debug info #8414

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13 changes: 10 additions & 3 deletions src/wasm/wasm-debug.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -195,6 +195,10 @@ struct LineState {
prologueEnd = true;
break;
}
case llvm::dwarf::DW_LNS_set_epilogue_begin: {
epilogueBegin = true;
break;
}
case llvm::dwarf::DW_LNS_copy: {
return true;
}
Expand Down Expand Up @@ -331,8 +335,8 @@ struct LineState {
if (prologueEnd) {
newOpcodes.push_back(makeItem(llvm::dwarf::DW_LNS_set_prologue_end));
}
if (epilogueBegin != old.epilogueBegin) {
Fatal() << "eb";
if (epilogueBegin) {
newOpcodes.push_back(makeItem(llvm::dwarf::DW_LNS_set_epilogue_begin));
}
if (useSpecial) {
// Emit a special, which emits a line automatically.
Expand All @@ -349,7 +353,10 @@ struct LineState {
}

// Some flags are automatically reset after each debug line.
void resetAfterLine() { prologueEnd = false; }
void resetAfterLine() {
prologueEnd = false;
epilogueBegin = false;
}

private:
llvm::DWARFYAML::LineTableOpcode
Expand Down
240 changes: 240 additions & 0 deletions test/passes/epilogue_begin_dwarf.bin.txt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,240 @@
DWARF debug info
================

Contains section .debug_info (58 bytes)
Contains section .debug_abbrev (39 bytes)
Contains section .debug_line (57 bytes)
Contains section .debug_str (212 bytes)

.debug_abbrev contents:
Abbrev table for offset: 0x00000000
[1] DW_TAG_compile_unit DW_CHILDREN_yes
DW_AT_producer DW_FORM_strp
DW_AT_language DW_FORM_data2
DW_AT_name DW_FORM_strp
DW_AT_stmt_list DW_FORM_sec_offset
DW_AT_comp_dir DW_FORM_strp
DW_AT_low_pc DW_FORM_addr
DW_AT_high_pc DW_FORM_data4

[2] DW_TAG_subprogram DW_CHILDREN_no
DW_AT_low_pc DW_FORM_addr
DW_AT_high_pc DW_FORM_data4
DW_AT_linkage_name DW_FORM_strp
DW_AT_name DW_FORM_strp
DW_AT_decl_file DW_FORM_data1
DW_AT_decl_line DW_FORM_data1
DW_AT_external DW_FORM_flag_present


.debug_info contents:
0x00000000: Compile Unit: length = 0x00000036 version = 0x0004 abbr_offset = 0x0000 addr_size = 0x04 (next unit at 0x0000003a)

0x0000000b: DW_TAG_compile_unit [1] *
DW_AT_producer [DW_FORM_strp] ( .debug_str[0x00000000] = "clang version 10.0.0 (/b/s/w/ir/cache/git/chromium.googlesource.com-external-github.com-llvm-llvm--project f2e65447b3cb6340883957e033e77095a025ebdc)")
DW_AT_language [DW_FORM_data2] (DW_LANG_C_plus_plus)
DW_AT_name [DW_FORM_strp] ( .debug_str[0x00000095] = "a.cpp")
DW_AT_stmt_list [DW_FORM_sec_offset] (0x00000000)
DW_AT_comp_dir [DW_FORM_strp] ( .debug_str[0x0000009b] = "/usr/local/google/home/azakai/Dev/emscripten")
DW_AT_low_pc [DW_FORM_addr] (0x0000000000000005)
DW_AT_high_pc [DW_FORM_data4] (0x00000002)

0x00000026: DW_TAG_subprogram [2]
DW_AT_low_pc [DW_FORM_addr] (0x0000000000000005)
DW_AT_high_pc [DW_FORM_data4] (0x00000002)
DW_AT_linkage_name [DW_FORM_strp] ( .debug_str[0x000000c8] = "_Z3foov")
DW_AT_name [DW_FORM_strp] ( .debug_str[0x000000d0] = "foo")
DW_AT_decl_file [DW_FORM_data1] ("/usr/local/google/home/azakai/Dev/emscripten/a.cpp")
DW_AT_decl_line [DW_FORM_data1] (3)
DW_AT_external [DW_FORM_flag_present] (true)

0x00000039: NULL

.debug_line contents:
debug_line[0x00000000]
Line table prologue:
total_length: 0x00000035
version: 4
prologue_length: 0x0000001d
min_inst_length: 1
max_ops_per_inst: 1
default_is_stmt: 1
line_base: -5
line_range: 14
opcode_base: 13
standard_opcode_lengths[DW_LNS_copy] = 0
standard_opcode_lengths[DW_LNS_advance_pc] = 1
standard_opcode_lengths[DW_LNS_advance_line] = 1
standard_opcode_lengths[DW_LNS_set_file] = 1
standard_opcode_lengths[DW_LNS_set_column] = 1
standard_opcode_lengths[DW_LNS_negate_stmt] = 0
standard_opcode_lengths[DW_LNS_set_basic_block] = 0
standard_opcode_lengths[DW_LNS_const_add_pc] = 0
standard_opcode_lengths[DW_LNS_fixed_advance_pc] = 1
standard_opcode_lengths[DW_LNS_set_prologue_end] = 0
standard_opcode_lengths[DW_LNS_set_epilogue_begin] = 0
standard_opcode_lengths[DW_LNS_set_isa] = 1
file_names[ 1]:
name: "a.cpp"
dir_index: 0
mod_time: 0x00000000
length: 0x00000000
0x00000027: 00 DW_LNE_set_address (0x0000000000000005)
0x0000002e: 14 address += 0, line += 2
0x0000000000000005 3 0 1 0 0 is_stmt

0x0000002f: 05 DW_LNS_set_column (1)
0x00000031: 0a DW_LNS_set_prologue_end
0x00000032: 0b DW_LNS_set_epilogue_begin
0x00000033: 21 address += 1, line += 1
0x0000000000000006 4 1 1 0 0 is_stmt prologue_end epilogue_begin

0x00000034: 02 DW_LNS_advance_pc (1)
0x00000036: 00 DW_LNE_end_sequence
0x0000000000000007 4 1 1 0 0 is_stmt end_sequence


.debug_str contents:
0x00000000: "clang version 10.0.0 (/b/s/w/ir/cache/git/chromium.googlesource.com-external-github.com-llvm-llvm--project f2e65447b3cb6340883957e033e77095a025ebdc)"
0x00000095: "a.cpp"
0x0000009b: "/usr/local/google/home/azakai/Dev/emscripten"
0x000000c8: "_Z3foov"
0x000000d0: "foo"
DWARF debug info
================

Contains section .debug_info (58 bytes)
Contains section .debug_abbrev (39 bytes)
Contains section .debug_line (63 bytes)
Contains section .debug_str (212 bytes)

.debug_abbrev contents:
Abbrev table for offset: 0x00000000
[1] DW_TAG_compile_unit DW_CHILDREN_yes
DW_AT_producer DW_FORM_strp
DW_AT_language DW_FORM_data2
DW_AT_name DW_FORM_strp
DW_AT_stmt_list DW_FORM_sec_offset
DW_AT_comp_dir DW_FORM_strp
DW_AT_low_pc DW_FORM_addr
DW_AT_high_pc DW_FORM_data4

[2] DW_TAG_subprogram DW_CHILDREN_no
DW_AT_low_pc DW_FORM_addr
DW_AT_high_pc DW_FORM_data4
DW_AT_linkage_name DW_FORM_strp
DW_AT_name DW_FORM_strp
DW_AT_decl_file DW_FORM_data1
DW_AT_decl_line DW_FORM_data1
DW_AT_external DW_FORM_flag_present


.debug_info contents:
0x00000000: Compile Unit: length = 0x00000036 version = 0x0004 abbr_offset = 0x0000 addr_size = 0x04 (next unit at 0x0000003a)

0x0000000b: DW_TAG_compile_unit [1] *
DW_AT_producer [DW_FORM_strp] ( .debug_str[0x00000000] = "clang version 10.0.0 (/b/s/w/ir/cache/git/chromium.googlesource.com-external-github.com-llvm-llvm--project f2e65447b3cb6340883957e033e77095a025ebdc)")
DW_AT_language [DW_FORM_data2] (DW_LANG_C_plus_plus)
DW_AT_name [DW_FORM_strp] ( .debug_str[0x00000095] = "a.cpp")
DW_AT_stmt_list [DW_FORM_sec_offset] (0x00000000)
DW_AT_comp_dir [DW_FORM_strp] ( .debug_str[0x0000009b] = "/usr/local/google/home/azakai/Dev/emscripten")
DW_AT_low_pc [DW_FORM_addr] (0x0000000000000000)
DW_AT_high_pc [DW_FORM_data4] (0x00000007)

0x00000026: DW_TAG_subprogram [2]
DW_AT_low_pc [DW_FORM_addr] (0x0000000000000000)
DW_AT_high_pc [DW_FORM_data4] (0x00000007)
DW_AT_linkage_name [DW_FORM_strp] ( .debug_str[0x000000c8] = "_Z3foov")
DW_AT_name [DW_FORM_strp] ( .debug_str[0x000000d0] = "foo")
DW_AT_decl_file [DW_FORM_data1] ("/usr/local/google/home/azakai/Dev/emscripten/a.cpp")
DW_AT_decl_line [DW_FORM_data1] (3)
DW_AT_external [DW_FORM_flag_present] (true)

0x00000039: NULL

.debug_line contents:
debug_line[0x00000000]
Line table prologue:
total_length: 0x0000003b
version: 4
prologue_length: 0x0000001d
min_inst_length: 1
max_ops_per_inst: 1
default_is_stmt: 1
line_base: -5
line_range: 14
opcode_base: 13
standard_opcode_lengths[DW_LNS_copy] = 0
standard_opcode_lengths[DW_LNS_advance_pc] = 1
standard_opcode_lengths[DW_LNS_advance_line] = 1
standard_opcode_lengths[DW_LNS_set_file] = 1
standard_opcode_lengths[DW_LNS_set_column] = 1
standard_opcode_lengths[DW_LNS_negate_stmt] = 0
standard_opcode_lengths[DW_LNS_set_basic_block] = 0
standard_opcode_lengths[DW_LNS_const_add_pc] = 0
standard_opcode_lengths[DW_LNS_fixed_advance_pc] = 1
standard_opcode_lengths[DW_LNS_set_prologue_end] = 0
standard_opcode_lengths[DW_LNS_set_epilogue_begin] = 0
standard_opcode_lengths[DW_LNS_set_isa] = 1
file_names[ 1]:
name: "a.cpp"
dir_index: 0
mod_time: 0x00000000
length: 0x00000000
0x00000027: 00 DW_LNE_set_address (0x0000000000000006)
0x0000002e: 03 DW_LNS_advance_line (4)
0x00000030: 05 DW_LNS_set_column (1)
0x00000032: 0a DW_LNS_set_prologue_end
0x00000033: 0b DW_LNS_set_epilogue_begin
0x00000034: 01 DW_LNS_copy
0x0000000000000006 4 1 1 0 0 is_stmt prologue_end epilogue_begin


0x00000035: 00 DW_LNE_set_address (0x0000000000000007)
0x0000003c: 00 DW_LNE_end_sequence
0x0000000000000007 4 1 1 0 0 is_stmt end_sequence


.debug_str contents:
0x00000000: "clang version 10.0.0 (/b/s/w/ir/cache/git/chromium.googlesource.com-external-github.com-llvm-llvm--project f2e65447b3cb6340883957e033e77095a025ebdc)"
0x00000095: "a.cpp"
0x0000009b: "/usr/local/google/home/azakai/Dev/emscripten"
0x000000c8: "_Z3foov"
0x000000d0: "foo"
(module
(type $0 (func (param i32) (result i32)))
(type $1 (func (param i32)))
(type $2 (func (result i32)))
(type $3 (func))
(type $4 (func (param i32 i32)))
(import "env" "__wasm_call_ctors" (func $fimport$0))
(import "env" "dlmalloc" (func $fimport$1 (param i32) (result i32)))
(import "env" "dlfree" (func $fimport$2 (param i32)))
(import "env" "setThrew" (func $fimport$3 (param i32 i32)))
(import "env" "stackSave" (func $fimport$4 (result i32)))
(import "env" "stackAlloc" (func $fimport$5 (param i32) (result i32)))
(import "env" "stackRestore" (func $fimport$6 (param i32)))
(import "env" "__growWasmMemory" (func $fimport$7 (param i32) (result i32)))
(global $global$0 i32 (i32.const 1532))
(export "__wasm_call_ctors" (func $fimport$0))
(export "_Z3foov" (func $fimport$0))
(export "__errno_location" (func $0))
(export "setThrew" (func $fimport$3))
(export "malloc" (func $fimport$1))
(export "free" (func $fimport$2))
(export "__data_end" (global $global$0))
(export "stackSave" (func $fimport$4))
(export "stackAlloc" (func $fimport$5))
(export "stackRestore" (func $fimport$6))
(export "__growWasmMemory" (func $fimport$7))
(func $0 (result i32)
;; code offset: 0x3
(i32.const 1024)
)
;; custom section "sourceMappingURL", size 15
;; custom section "sourceMappingURL", size 15
;; custom section ".debug_info", size 58
;; custom section ".debug_abbrev", size 39
;; custom section ".debug_line", size 63
;; custom section ".debug_str", size 212
)
1 change: 1 addition & 0 deletions test/passes/epilogue_begin_dwarf.passes
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
g_dwarfdump_roundtrip_dwarfdump
Binary file added test/passes/epilogue_begin_dwarf.wasm
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