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[Symbolizer] Handle {{{bt}}} symbolizer markup element.
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This adds support for backtrace generation to the llvm-symbolizer markup
filter, which is likely the largest use case.

Reviewed By: peter.smith

Differential Revision: https://reviews.llvm.org/D132706

(cherry picked from commit ea99225)
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@mysterymath @tru
mysterymath authored and tru committed Sep 7, 2022
1 parent 55b8f29 commit 7ce1ec5
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Showing 5 changed files with 326 additions and 6 deletions.
18 changes: 15 additions & 3 deletions llvm/docs/CommandGuide/llvm-symbolizer.rst
View file
Expand Up @@ -254,9 +254,21 @@ OPTIONS
and prints the results to standard output. The following markup elements are
not yet supported:

* ``{{bt}}``
* ``{{hexdict}}``
* ``{{dumpfile}}``
* ``{{{hexdict}}}``
* ``{{{dumpfile}}}``

The ``{{{bt}}}`` backtrace element reports frames using the following syntax:

``#<number>[.<inline>] <address> <function> <file>:<line>:<col> (<module>+<relative address>)``

``<inline>`` provides frame numbers for calls inlined into the caller
coresponding to ``<number>``. The inlined call numbers start at 1 and increase
from callee to caller.

``<address>`` is an address inside the call instruction to the function. The
address may not be the start of the instruction. ``<relative address>`` is
the corresponding virtual offset in the ``<module>`` loaded at that address.


.. _llvm-symbolizer-opt-f:

Expand Down
2 changes: 1 addition & 1 deletion llvm/docs/SymbolizerMarkupFormat.rst
View file
Expand Up @@ -205,7 +205,7 @@ human-readable symbolic form.
{{{data:0x12345678}}}
{{{data:0xffffffff9abcdef0}}}

``{{{bt:%u:%p}}}``, ``{{{bt:%u:%p:ra}}}``, ``{{{bt:%u:%p:pc}}}`` [#not_yet_implemented]_
``{{{bt:%u:%p}}}``, ``{{{bt:%u:%p:ra}}}``, ``{{{bt:%u:%p:pc}}}``

This represents one frame in a backtrace. It usually appears on a line by
itself (surrounded only by whitespace), in a sequence of such lines with
Expand Down
2 changes: 2 additions & 0 deletions llvm/include/llvm/DebugInfo/Symbolize/MarkupFilter.h
View file
Expand Up @@ -97,6 +97,7 @@ class MarkupFilter {
bool tryPresentation(const MarkupNode &Node);
bool trySymbol(const MarkupNode &Node);
bool tryPC(const MarkupNode &Node);
bool tryBackTrace(const MarkupNode &Node);
bool tryData(const MarkupNode &Node);

bool trySGR(const MarkupNode &Node);
Expand All @@ -118,6 +119,7 @@ class MarkupFilter {
Optional<SmallVector<uint8_t>> parseBuildID(StringRef Str) const;
Optional<std::string> parseMode(StringRef Str) const;
Optional<PCType> parsePCType(StringRef Str) const;
Optional<uint64_t> parseFrameNumber(StringRef Str) const;

bool checkTag(const MarkupNode &Node) const;
bool checkNumFields(const MarkupNode &Element, size_t Size) const;
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97 changes: 95 additions & 2 deletions llvm/lib/DebugInfo/Symbolize/MarkupFilter.cpp
View file
Expand Up @@ -27,6 +27,7 @@
#include "llvm/Demangle/Demangle.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/FormatVariadic.h"
#include "llvm/Support/WithColor.h"
#include "llvm/Support/raw_ostream.h"
Expand Down Expand Up @@ -216,6 +217,8 @@ bool MarkupFilter::tryPresentation(const MarkupNode &Node) {
return true;
if (tryPC(Node))
return true;
if (tryBackTrace(Node))
return true;
return tryData(Node);
}

Expand Down Expand Up @@ -269,8 +272,7 @@ bool MarkupFilter::tryPC(const MarkupNode &Node) {
printRawElement(Node);
return true;
}
if (LI->FileName == DILineInfo::BadString &&
LI->FunctionName == DILineInfo::BadString && LI->Line == 0) {
if (!*LI) {
printRawElement(Node);
return true;
}
Expand All @@ -286,6 +288,87 @@ bool MarkupFilter::tryPC(const MarkupNode &Node) {
return true;
}

bool MarkupFilter::tryBackTrace(const MarkupNode &Node) {
if (Node.Tag != "bt")
return false;
if (!checkNumFieldsAtLeast(Node, 2))
return true;
if (!checkNumFieldsAtMost(Node, 3))
return true;

Optional<uint64_t> FrameNumber = parseFrameNumber(Node.Fields[0]);
if (!FrameNumber)
return true;

Optional<uint64_t> Addr = parseAddr(Node.Fields[1]);
if (!Addr)
return true;

// Backtrace addresses are assumed to be return addresses by default.
PCType Type = PCType::ReturnAddress;
if (Node.Fields.size() == 3) {
Optional<PCType> ParsedType = parsePCType(Node.Fields[2]);
if (!ParsedType)
return true;
Type = *ParsedType;
}
*Addr = adjustAddr(*Addr, Type);

const MMap *MMap = getContainingMMap(*Addr);
if (!MMap) {
WithColor::error() << "no mmap covers address\n";
reportLocation(Node.Fields[0].begin());
printRawElement(Node);
return true;
}
uint64_t MRA = MMap->getModuleRelativeAddr(*Addr);

Expected<DIInliningInfo> II =
Symbolizer.symbolizeInlinedCode(MMap->Mod->BuildID, {MRA});
if (!II) {
WithColor::defaultErrorHandler(II.takeError());
printRawElement(Node);
return true;
}

highlight();
for (unsigned I = 0, E = II->getNumberOfFrames(); I != E; ++I) {
auto Header = formatv("{0, +6}", formatv("#{0}", FrameNumber)).sstr<16>();
// Don't highlight the # sign as a value.
size_t NumberIdx = Header.find("#") + 1;
OS << Header.substr(0, NumberIdx);
printValue(Header.substr(NumberIdx));
if (I == E - 1) {
OS << " ";
} else {
OS << '.';
printValue(formatv("{0, -2}", I + 1));
}
printValue(formatv(" {0:x16} ", *Addr));

DILineInfo LI = II->getFrame(I);
if (LI) {
printValue(LI.FunctionName);
OS << ' ';
printValue(LI.FileName);
OS << ':';
printValue(Twine(LI.Line));
OS << ':';
printValue(Twine(LI.Column));
OS << ' ';
}
OS << '(';
printValue(MMap->Mod->Name);
OS << "+";
printValue(formatv("{0:x}", MRA));
OS << ')';
if (I != E - 1)
OS << lineEnding();
}
restoreColor();
return true;
}

bool MarkupFilter::tryData(const MarkupNode &Node) {
if (Node.Tag != "data")
return false;
Expand Down Expand Up @@ -502,6 +585,16 @@ Optional<uint64_t> MarkupFilter::parseSize(StringRef Str) const {
return ID;
}

// Parse a frame number (%i in the spec).
Optional<uint64_t> MarkupFilter::parseFrameNumber(StringRef Str) const {
uint64_t ID;
if (Str.getAsInteger(10, ID)) {
reportTypeError(Str, "frame number");
return None;
}
return ID;
}

// Parse a build ID (%x in the spec).
Optional<SmallVector<uint8_t>> MarkupFilter::parseBuildID(StringRef Str) const {
std::string Bytes;
Expand Down
213 changes: 213 additions & 0 deletions llvm/test/DebugInfo/symbolize-filter-markup-bt.test
View file
@@ -0,0 +1,213 @@
REQUIRES: x86-registered-target
RUN: split-file %s %t
RUN: mkdir -p %t/.build-id/ab
RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %t/asm.s \
RUN: -o %t/.build-id/ab/cdef.debug
RUN: llvm-symbolizer --debug-file-directory=%t --filter-markup < %t/input \
RUN: > %t.output 2> %t.err
RUN: FileCheck %s --input-file=%t.output --match-full-lines \
RUN: --implicit-check-not {{.}}
RUN: FileCheck %s --check-prefix=ERR --input-file=%t.err --match-full-lines

CHECK: [[BEGIN:\[{3}]]ELF module #0x0 "a.o"; BuildID=abcdef [0x10-0x10f](r)[[END:\]{3}]]
CHECK: #0.1 0x0000000000000018 second /tmp[[SEP:[/\\]]]tmp.c:8:3 (a.o+0x8)
CHECK: #0 0x0000000000000018 first /tmp[[SEP]]tmp.c:4:3 (a.o+0x8)
CHECK: #1.1 0x0000000000000018 second /tmp[[SEP]]tmp.c:8:3 (a.o+0x8)
CHECK: #1 0x0000000000000018 first /tmp[[SEP]]tmp.c:4:3 (a.o+0x8)
CHECK: #0.1 0x0000000000000018 second /tmp[[SEP]]tmp.c:8:3 (a.o+0x8)
CHECK: #0 0x0000000000000018 first /tmp[[SEP]]tmp.c:4:3 (a.o+0x8)
CHECK: #0 0x0000000000000019 first /tmp[[SEP]]tmp.c:5:1 (a.o+0x9)
CHECK: #0 0x00000000000000fe (a.o+0xee)
CHECK: [[BEGIN]]bt:0:0x111[[END]]

ERR: error: expected at least 2 field(s); found 0
ERR: error: no mmap covers address
ERR: error: expected PC type; found ''
ERR: error: expected at most 3 field(s); found 4

;--- input
{{{module:0:a.o:elf:abcdef}}}
{{{mmap:0x10:256:load:0:r:0}}}
{{{bt:0:0x19}}}
{{{bt:1:0x19}}}
{{{bt:0:0x19:ra}}}
{{{bt:0:0x19:pc}}}
{{{bt:0:0xff}}}

{{{bt}}}
{{{bt:0:0x111}}}
{{{bt:0:0:}}}
{{{bt:0:0:pc:}}}
;--- asm.s
# Generated by running "clang -finline -g -S tmp.c" in the following tmp.c on
# Linux x86_64:
#
# static void second(void);
# void first(void) {
# second();
# }
# void second(void) {}
.text
.file "tmp.c"
.globl first # -- Begin function first
.p2align 4, 0x90
.type first,@function
first: # @first
.Lfunc_begin0:
.file 1 "/tmp" "tmp.c"
.loc 1 3 0 # tmp.c:3:0
.cfi_startproc
# %bb.0:
pushq %rbp
.cfi_def_cfa_offset 16
.cfi_offset %rbp, -16
movq %rsp, %rbp
.cfi_def_cfa_register %rbp
.Ltmp0:
.loc 1 8 3 prologue_end # tmp.c:8:3
callq first
.Ltmp1:
.loc 1 5 1 # tmp.c:5:1
popq %rbp
.cfi_def_cfa %rsp, 8
retq
.Ltmp2:
.Lfunc_end0:
.size first, .Lfunc_end0-first
.cfi_endproc
# -- End function
.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 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 16 # DW_AT_stmt_list
.byte 23 # DW_FORM_sec_offset
.byte 27 # DW_AT_comp_dir
.byte 14 # DW_FORM_strp
.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 46 # DW_TAG_subprogram
.byte 0 # DW_CHILDREN_no
.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 39 # DW_AT_prototyped
.byte 25 # DW_FORM_flag_present
.byte 63 # DW_AT_external
.byte 25 # DW_FORM_flag_present
.byte 32 # DW_AT_inline
.byte 11 # DW_FORM_data1
.byte 0 # EOM(1)
.byte 0 # EOM(2)
.byte 3 # 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 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 39 # DW_AT_prototyped
.byte 25 # DW_FORM_flag_present
.byte 63 # DW_AT_external
.byte 25 # DW_FORM_flag_present
.byte 0 # EOM(1)
.byte 0 # EOM(2)
.byte 4 # Abbreviation Code
.byte 29 # DW_TAG_inlined_subroutine
.byte 0 # DW_CHILDREN_no
.byte 49 # DW_AT_abstract_origin
.byte 19 # DW_FORM_ref4
.byte 17 # DW_AT_low_pc
.byte 1 # DW_FORM_addr
.byte 18 # DW_AT_high_pc
.byte 6 # DW_FORM_data4
.byte 88 # DW_AT_call_file
.byte 11 # DW_FORM_data1
.byte 89 # DW_AT_call_line
.byte 11 # DW_FORM_data1
.byte 87 # DW_AT_call_column
.byte 11 # DW_FORM_data1
.byte 0 # EOM(1)
.byte 0 # EOM(2)
.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 [1] 0xb:0x52 DW_TAG_compile_unit
.long .Linfo_string0 # DW_AT_producer
.short 12 # DW_AT_language
.long .Linfo_string1 # DW_AT_name
.long .Lline_table_start0 # DW_AT_stmt_list
.long .Linfo_string2 # DW_AT_comp_dir
.quad .Lfunc_begin0 # DW_AT_low_pc
.long .Lfunc_end0-.Lfunc_begin0 # DW_AT_high_pc
.byte 2 # Abbrev [2] 0x2a:0x8 DW_TAG_subprogram
.long .Linfo_string3 # DW_AT_name
.byte 1 # DW_AT_decl_file
.byte 7 # DW_AT_decl_line
# DW_AT_prototyped
# DW_AT_external
.byte 1 # DW_AT_inline
.byte 3 # Abbrev [3] 0x32:0x2a DW_TAG_subprogram
.quad .Lfunc_begin0 # DW_AT_low_pc
.long .Lfunc_end0-.Lfunc_begin0 # DW_AT_high_pc
.byte 1 # DW_AT_frame_base
.byte 86
.long .Linfo_string4 # DW_AT_name
.byte 1 # DW_AT_decl_file
.byte 3 # DW_AT_decl_line
# DW_AT_prototyped
# DW_AT_external
.byte 4 # Abbrev [4] 0x47:0x14 DW_TAG_inlined_subroutine
.long 42 # DW_AT_abstract_origin
.quad .Ltmp0 # DW_AT_low_pc
.long .Ltmp1-.Ltmp0 # DW_AT_high_pc
.byte 1 # DW_AT_call_file
.byte 4 # DW_AT_call_line
.byte 3 # DW_AT_call_column
.byte 0 # End Of Children Mark
.byte 0 # End Of Children Mark
.Ldebug_info_end0:
.section .debug_str,"MS",@progbits,1
.Linfo_string0:
.asciz "Debian clang version 13.0.1-6" # string offset=0
.Linfo_string1:
.asciz "tmp.c" # string offset=30
.Linfo_string2:
.asciz "/tmp" # string offset=36
.Linfo_string3:
.asciz "second" # string offset=85
.Linfo_string4:
.asciz "first" # string offset=92
.ident "Debian clang version 13.0.1-6"
.section ".note.GNU-stack","",@progbits
.addrsig
.addrsig_sym first
.section .debug_line,"",@progbits
.Lline_table_start0:

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