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[lldb] Fix prologue size calculation for discontinuous functions #131597

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Merged
merged 2 commits into from
Mar 20, 2025
Merged

[lldb] Fix prologue size calculation for discontinuous functions #131597

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[lldb] Fix prologue size calculation for discontinuous functions
labath Mar 17, 2025
2b7e15a
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labath Mar 19, 2025
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20 changes: 11 additions & 9 deletions lldb/source/Symbol/Function.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -662,10 +662,12 @@ uint32_t Function::GetPrologueByteSize() {
}
}

const addr_t func_start_file_addr =
m_range.GetBaseAddress().GetFileAddress();
const addr_t func_end_file_addr =
func_start_file_addr + m_range.GetByteSize();
AddressRange entry_range;
m_block.GetRangeContainingAddress(m_address, entry_range);
const addr_t range_start_file_addr = m_address.GetFileAddress();
const addr_t range_end_file_addr =
entry_range.GetBaseAddress().GetFileAddress() +
entry_range.GetByteSize();
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Any reason to do it this way rather than:

const addr_t range_start_file_addr = entry_range.GetBaseAddress().GetFileAddress();
const addr_t range_end_file_addr = range_start_file_addr + entry_range.GetByteSize();

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Yes, because in the most general case, the entry point may not be at the start of any particular range (either because of a perverse compiler or because the linker placed two of the ranges next to each other and we have merged them into one).

I'm going to add a comment about that.


// Now calculate the offset to pass the subsequent line 0 entries.
uint32_t first_non_zero_line = prologue_end_line_idx;
Expand All @@ -677,7 +679,7 @@ uint32_t Function::GetPrologueByteSize() {
break;
}
if (line_entry.range.GetBaseAddress().GetFileAddress() >=
func_end_file_addr)
range_end_file_addr)
break;

first_non_zero_line++;
Expand All @@ -694,13 +696,13 @@ uint32_t Function::GetPrologueByteSize() {

// Verify that this prologue end file address in the function's address
// range just to be sure
if (func_start_file_addr < prologue_end_file_addr &&
prologue_end_file_addr < func_end_file_addr) {
m_prologue_byte_size = prologue_end_file_addr - func_start_file_addr;
if (range_start_file_addr < prologue_end_file_addr &&
prologue_end_file_addr < range_end_file_addr) {
m_prologue_byte_size = prologue_end_file_addr - range_start_file_addr;
}

if (prologue_end_file_addr < line_zero_end_file_addr &&
line_zero_end_file_addr < func_end_file_addr) {
line_zero_end_file_addr < range_end_file_addr) {
m_prologue_byte_size +=
line_zero_end_file_addr - prologue_end_file_addr;
}
Expand Down
25 changes: 23 additions & 2 deletions lldb/test/Shell/SymbolFile/DWARF/x86/discontinuous-function.s
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Original file line number Diff line number Diff line change
Expand Up @@ -16,22 +16,32 @@ image lookup -v -n foo
# CHECK-LABEL: image lookup -v -n foo
# CHECK: 1 match found in {{.*}}
# CHECK: Summary: input.o`foo
# CHECK: Function: id = {{.*}}, name = "foo", ranges = [0x0000000000000000-0x000000000000000e)[0x0000000000000014-0x000000000000001c)
# CHECK: Function: id = {{.*}}, name = "foo", ranges = [0x0000000000000000-0x000000000000000f)[0x0000000000000015-0x000000000000001d)

image lookup -v --regex -n '^foo$'
# CHECK-LABEL: image lookup -v --regex -n '^foo$'
# CHECK: 1 match found in {{.*}}
# CHECK: Summary: input.o`foo
# CHECK: Function: id = {{.*}}, name = "foo", ranges = [0x0000000000000000-0x000000000000000e)[0x0000000000000014-0x000000000000001c)
# CHECK: Function: id = {{.*}}, name = "foo", ranges = [0x0000000000000000-0x000000000000000f)[0x0000000000000015-0x000000000000001d)

expr -- &foo
# CHECK-LABEL: expr -- &foo
# CHECK: (void (*)()) $0 = 0x0000000000000007

breakpoint set --name foo --skip-prologue false
# CHECK-LABEL: breakpoint set --name foo --skip-prologue false
# CHECK: Breakpoint 1: where = input.o`foo at -:1, address = 0x0000000000000007

breakpoint set --name foo --skip-prologue true
# CHECK-LABEL: breakpoint set --name foo --skip-prologue true
# CHECK: Breakpoint 2: where = input.o`foo + 1 at -:2, address = 0x0000000000000008

#--- input.s
.text

.file 0 "." "-"
foo.__part.1:
.loc 0 10
.cfi_startproc
callq bar
jmp foo.__part.3
Expand All @@ -41,7 +51,10 @@ foo.__part.1:

.type foo,@function
foo:
.loc 0 1
.cfi_startproc
nop
.loc 0 2 prologue_end
cmpl $0, %edi
je foo.__part.2
jmp foo.__part.1
Expand All @@ -51,13 +64,15 @@ foo:

bar:
.cfi_startproc
.loc 0 100
movl $47, %eax
retq
.cfi_endproc
.Lbar_end:
.size bar, .Lbar_end-bar

foo.__part.2:
.loc 0 20
.cfi_startproc
callq baz
jmp foo.__part.3
Expand All @@ -66,6 +81,7 @@ foo.__part.2:
.cfi_endproc

foo.__part.3:
.loc 0 30
.cfi_startproc
retq
.Lfoo.__part.3_end:
Expand All @@ -87,6 +103,8 @@ foo.__part.3:
.byte 35 # DW_FORM_rnglistx
.byte 116 # DW_AT_rnglists_base
.byte 23 # DW_FORM_sec_offset
.byte 16 # DW_AT_stmt_list
.byte 23 # DW_FORM_sec_offset
.byte 0 # EOM(1)
.byte 0 # EOM(2)
.byte 2 # Abbreviation Code
Expand Down Expand Up @@ -127,6 +145,7 @@ foo.__part.3:
.quad 0 # DW_AT_low_pc
.byte 1 # DW_AT_ranges
.long .Lrnglists_table_base0 # DW_AT_rnglists_base
.long .Lline_table_start0 # DW_AT_stmt_list
.byte 2 # Abbrev [2] DW_TAG_subprogram
.quad bar # DW_AT_low_pc
.quad .Lbar_end # DW_AT_high_pc
Expand Down Expand Up @@ -183,3 +202,5 @@ foo.__part.3:
.Ldebug_list_header_end0:

.section ".note.GNU-stack","",@progbits
.section .debug_line,"",@progbits
.Lline_table_start0: