In addition to the existing support for libbfd and calling out to
an external addr2line command, add support for using libllvm directly.
This is both faster than libbfd, and can be enabled in distro builds
(the LLVM license has an explicit provision for GPLv2 compatibility).
Thus, it is set as the primary choice if available.
As an example, running perf report on a medium-size profile with
DWARF-based backtraces took 58 seconds with LLVM, 78 seconds with
libbfd, 153 seconds with external llvm-addr2line, and I got tired
and aborted the test after waiting for 55 minutes with external
bfd addr2line (which is the default for perf as compiled by distributions
today). Evidently, for this case, the bfd addr2line process needs
18 seconds (on a 5.2 GHz Zen 3) to load the .debug ELF in question,
hits the 1-second timeout and gets killed during initialization,
getting restarted anew every time. Having an in-process addr2line
makes this much more robust.
As future extensions, libllvm can be used in many other places where
we currently use libbfd or other libraries:
- Symbol enumeration (in particular, for PE binaries).
- Demangling (including non-Itanium demangling, e.g. Microsoft
or Rust).
- Disassembling (perf annotate).
However, these are much less pressing; most people don't profile
PE binaries, and perf has non-bfd paths for ELF. The same with
demangling; the default _cxa_demangle path works fine for most
users. Disassembling is coming in a later patch in the series;
however do note that while bfd objdump can be slow on large binaries,
it is possible to use --objdump=llvm-objdump to get the speed benefits.
(It appears LLVM-based demangling is very simple, should we want
that.)
Tested with LLVM 14, 15, 16, 18 and 19. For some reason, LLVM 12 was not
correctly detected using feature_check, and thus was not tested.
Signed-off-by: Steinar H. Gunderson <[email protected]>
---
tools/build/Makefile.feature | 1 +
tools/perf/Makefile.config | 15 ++++
tools/perf/builtin-version.c | 1 +
tools/perf/util/Build | 1 +
tools/perf/util/llvm-c-helpers.cpp | 130 +++++++++++++++++++++++++++++
tools/perf/util/llvm-c-helpers.h | 47 +++++++++++
tools/perf/util/srcline.c | 57 ++++++++++++-
7 files changed, 251 insertions(+), 1 deletion(-)
create mode 100644 tools/perf/util/llvm-c-helpers.cpp
create mode 100644 tools/perf/util/llvm-c-helpers.h
diff --git a/tools/build/Makefile.feature b/tools/build/Makefile.feature
index 1e2ab148d5db..278b26216254 100644
--- a/tools/build/Makefile.feature
+++ b/tools/build/Makefile.feature
@@ -136,6 +136,7 @@ FEATURE_DISPLAY ?= \
libunwind \
libdw-dwarf-unwind \
libcapstone \
+ llvm \
zlib \
lzma \
get_cpuid \
diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 7f1e016a9253..414a37f712bd 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -969,6 +969,21 @@ ifdef BUILD_NONDISTRO
endif
endif
+ifndef NO_LLVM
+ $(call feature_check,llvm)
+ ifeq ($(feature-llvm), 1)
+ CFLAGS += -DHAVE_LLVM_SUPPORT
+ CXXFLAGS += -DHAVE_LLVM_SUPPORT
+ CXXFLAGS += $(shell $(LLVM_CONFIG) --cxxflags)
+ LIBLLVM = $(shell $(LLVM_CONFIG) --libs all) $(shell $(LLVM_CONFIG) --system-libs)
+ EXTLIBS += -L$(shell $(LLVM_CONFIG) --libdir) $(LIBLLVM)
+ $(call detected,CONFIG_LLVM)
+ else
+ $(warning No libllvm found, slower source file resolution, please install llvm-devel/llvm-dev)
+ NO_LLVM := 1
+ endif
+endif
+
ifndef NO_DEMANGLE
$(call feature_check,cxa-demangle)
ifeq ($(feature-cxa-demangle), 1)
diff --git a/tools/perf/builtin-version.c b/tools/perf/builtin-version.c
index 398aa53e9e2e..94d8e13a688f 100644
--- a/tools/perf/builtin-version.c
+++ b/tools/perf/builtin-version.c
@@ -65,6 +65,7 @@ static void library_status(void)
STATUS(HAVE_LIBBFD_SUPPORT, libbfd);
STATUS(HAVE_DEBUGINFOD_SUPPORT, debuginfod);
STATUS(HAVE_LIBELF_SUPPORT, libelf);
+ STATUS(HAVE_LLVM_SUPPORT, libllvm);
STATUS(HAVE_LIBNUMA_SUPPORT, libnuma);
STATUS(HAVE_LIBNUMA_SUPPORT, numa_num_possible_cpus);
STATUS(HAVE_LIBPERL_SUPPORT, libperl);
diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index da64efd8718f..32c4e5e634ed 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -226,6 +226,7 @@ perf-$(CONFIG_CXX_DEMANGLE) += demangle-cxx.o
perf-y += demangle-ocaml.o
perf-y += demangle-java.o
perf-y += demangle-rust.o
+perf-$(CONFIG_LLVM) += llvm-c-helpers.o
ifdef CONFIG_JITDUMP
perf-$(CONFIG_LIBELF) += jitdump.o
diff --git a/tools/perf/util/llvm-c-helpers.cpp b/tools/perf/util/llvm-c-helpers.cpp
new file mode 100644
index 000000000000..cde3f1f03af0
--- /dev/null
+++ b/tools/perf/util/llvm-c-helpers.cpp
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Must come before the linux/compiler.h include, which defines several
+ * macros (e.g. noinline) that conflict with compiler builtins used
+ * by LLVM.
+ */
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-parameter" /* Needed for LLVM <= 15 */
+#include <llvm/DebugInfo/Symbolize/Symbolize.h>
+#pragma GCC diagnostic pop
+
+#include <stdio.h>
+#include <sys/types.h>
+#include <linux/compiler.h>
+#include "symbol_conf.h"
+#include "llvm-c-helpers.h"
+
+using namespace llvm;
+using llvm::symbolize::LLVMSymbolizer;
+
+/*
+ * Allocate a static LLVMSymbolizer, which will live to the end of the program.
+ * Unlike the bfd paths, LLVMSymbolizer has its own cache, so we do not need
+ * to store anything in the dso struct.
+ */
+static LLVMSymbolizer *get_symbolizer()
+{
+ static LLVMSymbolizer *instance = nullptr;
+ if (instance == nullptr) {
+ LLVMSymbolizer::Options opts;
+ /*
+ * LLVM sometimes demangles slightly different from the rest
+ * of the code, and this mismatch can cause new_inline_sym()
+ * to get confused and mark non-inline symbol as inlined
+ * (since the name does not properly match up with base_sym).
+ * Thus, disable the demangling and let the rest of the code
+ * handle it.
+ */
+ opts.Demangle = false;
+ instance = new LLVMSymbolizer(opts);
+ }
+ return instance;
+}
+
+/* Returns 0 on error, 1 on success. */
+static int extract_file_and_line(const DILineInfo& line_info, char **file,
+ unsigned int *line)
+{
+ if (file) {
+ if (line_info.FileName == "<invalid>") {
+ /* Match the convention of libbfd. */
+ *file = nullptr;
+ } else {
+ /* The caller expects to get something it can free(). */
+ *file = strdup(line_info.FileName.c_str());
+ if (*file == nullptr)
+ return 0;
+ }
+ }
+ if (line)
+ *line = line_info.Line;
+ return 1;
+}
+
+extern "C"
+int llvm_addr2line(const char *dso_name, u64 addr,
+ char **file, unsigned int *line,
+ bool unwind_inlines,
+ llvm_a2l_frame** inline_frames)
+{
+ LLVMSymbolizer *symbolizer = get_symbolizer();
+ object::SectionedAddress sectioned_addr = {
+ addr,
+ object::SectionedAddress::UndefSection
+ };
+
+ if (unwind_inlines) {
+ Expected<DIInliningInfo> res_or_err =
+ symbolizer->symbolizeInlinedCode(dso_name,
+ sectioned_addr);
+ if (!res_or_err)
+ return 0;
+ unsigned num_frames = res_or_err->getNumberOfFrames();
+ if (num_frames == 0)
+ return 0;
+
+ if (extract_file_and_line(
+ res_or_err->getFrame(0), file, line) == 0)
+ return 0;
+
+ *inline_frames = (llvm_a2l_frame*)malloc(
+ sizeof(**inline_frames) * num_frames);
+ if (*inline_frames == nullptr)
+ return 0;
+
+ for (unsigned i = 0; i < num_frames; ++i) {
+ const DILineInfo& src = res_or_err->getFrame(i);
+ llvm_a2l_frame& dst = (*inline_frames)[i];
+ if (src.FileName == "<invalid>")
+ /* Match the convention of libbfd. */
+ dst.filename = nullptr;
+ else
+ dst.filename = strdup(src.FileName.c_str());
+ dst.funcname = strdup(src.FunctionName.c_str());
+ dst.line = src.Line;
+
+ if (dst.filename == nullptr ||
+ dst.funcname == nullptr) {
+ for (unsigned j = 0; j <= i; ++j) {
+ free((*inline_frames)[j].filename);
+ free((*inline_frames)[j].funcname);
+ }
+ free(*inline_frames);
+ return 0;
+ }
+ }
+
+ return num_frames;
+ } else {
+ if (inline_frames)
+ *inline_frames = nullptr;
+
+ Expected<DILineInfo> res_or_err =
+ symbolizer->symbolizeCode(dso_name, sectioned_addr);
+ if (!res_or_err)
+ return 0;
+ return extract_file_and_line(*res_or_err, file, line);
+ }
+}
diff --git a/tools/perf/util/llvm-c-helpers.h b/tools/perf/util/llvm-c-helpers.h
new file mode 100644
index 000000000000..1b28cdc9f9b7
--- /dev/null
+++ b/tools/perf/util/llvm-c-helpers.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PERF_LLVM_C_HELPERS
+#define __PERF_LLVM_C_HELPERS 1
+
+/*
+ * Helpers to call into LLVM C++ code from C, for the parts that do not have
+ * C APIs.
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct llvm_a2l_frame {
+ char *filename;
+ char *funcname;
+ unsigned int line;
+};
+
+/*
+ * Implement addr2line() using libLLVM. LLVM is a C++ API, and
+ * many of the linux/ headers cannot be included in a C++ compile unit,
+ * so we need to make a little bridge code here. llvm_addr2line() will
+ * convert the inline frame information from LLVM's internal structures
+ * and put them into a flat array given in inline_frames. The caller
+ * is then responsible for taking that array and convert it into perf's
+ * regular inline frame structures (which depend on e.g. struct list_head).
+ *
+ * If the address could not be resolved, or an error occurred (e.g. OOM),
+ * returns 0. Otherwise, returns the number of inline frames (which means 1
+ * if the address was not part of an inlined function). If unwind_inlines
+ * is set and the return code is nonzero, inline_frames will be set to
+ * a newly allocated array with that length. The caller is then responsible
+ * for freeing both the strings and the array itself.
+ */
+int llvm_addr2line(const char *dso_name,
+ u64 addr,
+ char **file,
+ unsigned int *line,
+ bool unwind_inlines,
+ struct llvm_a2l_frame **inline_frames);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __PERF_LLVM_C_HELPERS */
diff --git a/tools/perf/util/srcline.c b/tools/perf/util/srcline.c
index 9d670d8c1c08..0505b4c16608 100644
--- a/tools/perf/util/srcline.c
+++ b/tools/perf/util/srcline.c
@@ -16,6 +16,9 @@
#include "util/debug.h"
#include "util/callchain.h"
#include "util/symbol_conf.h"
+#ifdef HAVE_LLVM_SUPPORT
+#include "util/llvm-c-helpers.h"
+#endif
#include "srcline.h"
#include "string2.h"
#include "symbol.h"
@@ -130,7 +133,59 @@ static struct symbol *new_inline_sym(struct dso *dso,
#define MAX_INLINE_NEST 1024
-#ifdef HAVE_LIBBFD_SUPPORT
+#ifdef HAVE_LLVM_SUPPORT
+
+static void free_llvm_inline_frames(struct llvm_a2l_frame *inline_frames,
+ int num_frames)
+{
+ if (inline_frames != NULL) {
+ for (int i = 0; i < num_frames; ++i) {
+ free(inline_frames[i].filename);
+ free(inline_frames[i].funcname);
+ }
+ free(inline_frames);
+ }
+}
+
+static int addr2line(const char *dso_name, u64 addr,
+ char **file, unsigned int *line, struct dso *dso,
+ bool unwind_inlines, struct inline_node *node,
+ struct symbol *sym)
+{
+ struct llvm_a2l_frame *inline_frames = NULL;
+ int num_frames = llvm_addr2line(dso_name, addr, file, line,
+ node && unwind_inlines, &inline_frames);
+
+ if (num_frames == 0 || !inline_frames) {
+ /* Error, or we didn't want inlines. */
+ return num_frames;
+ }
+
+ for (int i = 0; i < num_frames; ++i) {
+ struct symbol *inline_sym =
+ new_inline_sym(dso, sym, inline_frames[i].funcname);
+ char *srcline = NULL;
+
+ if (inline_frames[i].filename)
+ srcline = srcline_from_fileline(
+ inline_frames[i].filename,
+ inline_frames[i].line);
+ if (inline_list__append(inline_sym, srcline, node) != 0) {
+ free_llvm_inline_frames(inline_frames, num_frames);
+ return 0;
+ }
+ }
+ free_llvm_inline_frames(inline_frames, num_frames);
+
+ return num_frames;
+}
+
+void dso__free_a2l(struct dso *)
+{
+ /* Nothing to free. */
+}
+
+#elif defined(HAVE_LIBBFD_SUPPORT)
/*
* Implement addr2line using libbfd.
--
2.43.0
The Capstone disassembler code has a useful code snippet to read
the bytes for a given code symbol into memory. Split it out into
its own function, so that the LLVM disassembler can use it in
the next patch.
Signed-off-by: Steinar H. Gunderson <[email protected]>
---
tools/perf/util/disasm.c | 90 +++++++++++++++++++++++++---------------
1 file changed, 56 insertions(+), 34 deletions(-)
diff --git a/tools/perf/util/disasm.c b/tools/perf/util/disasm.c
index 72aec8f61b94..c0dbb955e61a 100644
--- a/tools/perf/util/disasm.c
+++ b/tools/perf/util/disasm.c
@@ -1396,6 +1396,53 @@ static int find_file_offset(u64 start, u64 len, u64 pgoff, void *arg)
return 0;
}
+static u8 *
+read_symbol(const char *filename, struct map *map, struct symbol *sym,
+ u64 *len, bool *is_64bit)
+{
+ struct dso *dso = map__dso(map);
+ struct nscookie nsc;
+ u64 start = map__rip_2objdump(map, sym->start);
+ u64 end = map__rip_2objdump(map, sym->end);
+ int fd, count;
+ u8 *buf = NULL;
+ struct find_file_offset_data data = {
+ .ip = start,
+ };
+
+ *is_64bit = false;
+
+ nsinfo__mountns_enter(dso__nsinfo(dso), &nsc);
+ fd = open(filename, O_RDONLY);
+ nsinfo__mountns_exit(&nsc);
+ if (fd < 0)
+ return NULL;
+
+ if (file__read_maps(fd, /*exe=*/true, find_file_offset, &data,
+ is_64bit) == 0)
+ goto err;
+
+ *len = end - start;
+ buf = malloc(*len);
+ if (buf == NULL)
+ goto err;
+
+ count = pread(fd, buf, *len, data.offset);
+ close(fd);
+ fd = -1;
+
+ if ((u64)count != *len)
+ goto err;
+
+ return buf;
+
+err:
+ if (fd >= 0)
+ close(fd);
+ free(buf);
+ return NULL;
+}
+
static void print_capstone_detail(cs_insn *insn, char *buf, size_t len,
struct annotate_args *args, u64 addr)
{
@@ -1458,19 +1505,13 @@ static int symbol__disassemble_capstone(char *filename, struct symbol *sym,
{
struct annotation *notes = symbol__annotation(sym);
struct map *map = args->ms.map;
- struct dso *dso = map__dso(map);
- struct nscookie nsc;
u64 start = map__rip_2objdump(map, sym->start);
- u64 end = map__rip_2objdump(map, sym->end);
- u64 len = end - start;
+ u64 len;
u64 offset;
- int i, fd, count;
+ int i, count;
bool is_64bit = false;
bool needs_cs_close = false;
u8 *buf = NULL;
- struct find_file_offset_data data = {
- .ip = start,
- };
csh handle;
cs_insn *insn;
char disasm_buf[512];
@@ -1479,31 +1520,9 @@ static int symbol__disassemble_capstone(char *filename, struct symbol *sym,
if (args->options->objdump_path)
return -1;
- nsinfo__mountns_enter(dso__nsinfo(dso), &nsc);
- fd = open(filename, O_RDONLY);
- nsinfo__mountns_exit(&nsc);
- if (fd < 0)
- return -1;
-
- if (file__read_maps(fd, /*exe=*/true, find_file_offset, &data,
- &is_64bit) == 0)
- goto err;
-
- if (open_capstone_handle(args, is_64bit, &handle) < 0)
- goto err;
-
- needs_cs_close = true;
-
- buf = malloc(len);
+ buf = read_symbol(filename, map, sym, &len, &is_64bit);
if (buf == NULL)
- goto err;
-
- count = pread(fd, buf, len, data.offset);
- close(fd);
- fd = -1;
-
- if ((u64)count != len)
- goto err;
+ return -1;
/* add the function address and name */
scnprintf(disasm_buf, sizeof(disasm_buf), "%#"PRIx64" <%s>:",
@@ -1521,6 +1540,11 @@ static int symbol__disassemble_capstone(char *filename, struct symbol *sym,
annotation_line__add(&dl->al, ¬es->src->source);
+ if (open_capstone_handle(args, is_64bit, &handle) < 0)
+ goto err;
+
+ needs_cs_close = true;
+
count = cs_disasm(handle, buf, len, start, len, &insn);
for (i = 0, offset = 0; i < count; i++) {
int printed;
@@ -1565,8 +1589,6 @@ static int symbol__disassemble_capstone(char *filename, struct symbol *sym,
return count < 0 ? count : 0;
err:
- if (fd >= 0)
- close(fd);
if (needs_cs_close) {
struct disasm_line *tmp;
--
2.43.0
Support using LLVM as a disassembler method, allowing helperless
annotation in non-distro builds. (It is also much faster than
using libbfd or bfd objdump on binaries with a lot of debug
information.)
This is nearly identical to the output of llvm-objdump; there are
some very rare whitespace differences, some minor changes to demangling
(since we use perf's regular demangling and not LLVM's own) and
the occasional case where llvm-objdump makes a different choice
when multiple symbols share the same address. It should work across
all of LLVM's supported architectures, although I've only tested 64-bit
x86, and finding the right triple from perf's idea of machine
architecture can sometimes be a bit tricky. Ideally, we should have
some way of finding the triplet just from the file itself.
Signed-off-by: Steinar H. Gunderson <[email protected]>
---
tools/perf/util/disasm.c | 195 +++++++++++++++++++++++++++++
tools/perf/util/llvm-c-helpers.cpp | 62 +++++++++
tools/perf/util/llvm-c-helpers.h | 11 ++
3 files changed, 268 insertions(+)
diff --git a/tools/perf/util/disasm.c b/tools/perf/util/disasm.c
index c0dbb955e61a..9c07d2a8c8a8 100644
--- a/tools/perf/util/disasm.c
+++ b/tools/perf/util/disasm.c
@@ -43,6 +43,7 @@ static int call__scnprintf(struct ins *ins, char *bf, size_t size,
static void ins__sort(struct arch *arch);
static int disasm_line__parse(char *line, const char **namep, char **rawp);
+static char *expand_tabs(char *line, char **storage, size_t *storage_len);
static __attribute__((constructor)) void symbol__init_regexpr(void)
{
@@ -1378,7 +1379,9 @@ static int open_capstone_handle(struct annotate_args *args, bool is_64bit,
return 0;
}
+#endif
+#if defined(HAVE_LIBCAPSTONE_SUPPORT) || defined(HAVE_LLVM_SUPPORT)
struct find_file_offset_data {
u64 ip;
u64 offset;
@@ -1442,7 +1445,9 @@ read_symbol(const char *filename, struct map *map, struct symbol *sym,
free(buf);
return NULL;
}
+#endif
+#ifdef HAVE_LIBCAPSTONE_SUPPORT
static void print_capstone_detail(cs_insn *insn, char *buf, size_t len,
struct annotate_args *args, u64 addr)
{
@@ -1606,6 +1611,191 @@ static int symbol__disassemble_capstone(char *filename, struct symbol *sym,
}
#endif
+#ifdef HAVE_LLVM_SUPPORT
+#include <llvm-c/Disassembler.h>
+#include <llvm-c/Target.h>
+#include "util/llvm-c-helpers.h"
+
+struct symbol_lookup_storage {
+ u64 branch_addr;
+ u64 pcrel_load_addr;
+};
+
+/*
+ * Whenever LLVM wants to resolve an address into a symbol, it calls this
+ * callback. We don't ever actually _return_ anything (in particular, because
+ * it puts quotation marks around what we return), but we use this as a hint
+ * that there is a branch or PC-relative address in the expression that we
+ * should add some textual annotation for after the instruction. The caller
+ * will use this information to add the actual annotation.
+ */
+static const char *
+symbol_lookup_callback(void *disinfo, uint64_t value,
+ uint64_t *ref_type,
+ uint64_t address __maybe_unused,
+ const char **ref __maybe_unused)
+{
+ struct symbol_lookup_storage *storage =
+ (struct symbol_lookup_storage *)disinfo;
+ if (*ref_type == LLVMDisassembler_ReferenceType_In_Branch)
+ storage->branch_addr = value;
+ else if (*ref_type == LLVMDisassembler_ReferenceType_In_PCrel_Load)
+ storage->pcrel_load_addr = value;
+ *ref_type = LLVMDisassembler_ReferenceType_InOut_None;
+ return NULL;
+}
+
+static int symbol__disassemble_llvm(char *filename, struct symbol *sym,
+ struct annotate_args *args)
+{
+ struct annotation *notes = symbol__annotation(sym);
+ struct map *map = args->ms.map;
+ struct dso *dso = map__dso(map);
+ u64 start = map__rip_2objdump(map, sym->start);
+ u8 *buf;
+ u64 len;
+ u64 pc;
+ bool is_64bit;
+ char triplet[64];
+ char disasm_buf[2048];
+ size_t disasm_len;
+ struct disasm_line *dl;
+ LLVMDisasmContextRef disasm = NULL;
+ struct symbol_lookup_storage storage;
+ char *line_storage = NULL;
+ size_t line_storage_len = 0;
+
+ if (args->options->objdump_path)
+ return -1;
+
+ LLVMInitializeAllTargetInfos();
+ LLVMInitializeAllTargetMCs();
+ LLVMInitializeAllDisassemblers();
+
+ buf = read_symbol(filename, map, sym, &len, &is_64bit);
+ if (buf == NULL)
+ return -1;
+
+ if (arch__is(args->arch, "x86")) {
+ if (is_64bit)
+ scnprintf(triplet, sizeof(triplet), "x86_64-pc-linux");
+ else
+ scnprintf(triplet, sizeof(triplet), "i686-pc-linux");
+ } else {
+ scnprintf(triplet, sizeof(triplet), "%s-linux-gnu",
+ args->arch->name);
+ }
+
+ disasm = LLVMCreateDisasm(
+ triplet, &storage, 0, NULL, symbol_lookup_callback);
+ if (disasm == NULL)
+ goto err;
+
+ if (args->options->disassembler_style &&
+ !strcmp(args->options->disassembler_style, "intel"))
+ LLVMSetDisasmOptions(
+ disasm, LLVMDisassembler_Option_AsmPrinterVariant);
+
+ /*
+ * This needs to be set after AsmPrinterVariant, due to a bug in LLVM;
+ * setting AsmPrinterVariant makes a new instruction printer, making it
+ * forget about the PrintImmHex flag (which is applied before if both
+ * are given to the same call).
+ */
+ LLVMSetDisasmOptions(disasm, LLVMDisassembler_Option_PrintImmHex);
+
+ /* add the function address and name */
+ scnprintf(disasm_buf, sizeof(disasm_buf), "%#"PRIx64" <%s>:",
+ start, sym->name);
+
+ args->offset = -1;
+ args->line = disasm_buf;
+ args->line_nr = 0;
+ args->fileloc = NULL;
+ args->ms.sym = sym;
+
+ dl = disasm_line__new(args);
+ if (dl == NULL)
+ goto err;
+
+ annotation_line__add(&dl->al, ¬es->src->source);
+
+ pc = start;
+ for (u64 offset = 0; offset < len; ) {
+ unsigned int ins_len;
+
+ storage.branch_addr = 0;
+ storage.pcrel_load_addr = 0;
+
+ ins_len = LLVMDisasmInstruction(
+ disasm, buf + offset, len - offset, pc,
+ disasm_buf, sizeof(disasm_buf));
+ if (ins_len == 0)
+ goto err;
+ disasm_len = strlen(disasm_buf);
+
+ if (storage.branch_addr != 0) {
+ char *name = llvm_name_for_code(
+ dso, filename, storage.branch_addr);
+ if (name != NULL) {
+ disasm_len += scnprintf(
+ disasm_buf + disasm_len,
+ sizeof(disasm_buf) - disasm_len,
+ " <%s>", name);
+ free(name);
+ }
+ }
+ if (storage.pcrel_load_addr != 0) {
+ char *name = llvm_name_for_data(
+ dso, filename, storage.pcrel_load_addr);
+ disasm_len += scnprintf(disasm_buf + disasm_len,
+ sizeof(disasm_buf) - disasm_len,
+ " # %#"PRIx64,
+ storage.pcrel_load_addr);
+ if (name) {
+ disasm_len += scnprintf(
+ disasm_buf + disasm_len,
+ sizeof(disasm_buf) - disasm_len,
+ " <%s>", name);
+ free(name);
+ }
+ }
+
+ args->offset = offset;
+ args->line = expand_tabs(
+ disasm_buf, &line_storage, &line_storage_len);
+ args->line_nr = 0;
+ args->fileloc = NULL;
+ args->ms.sym = sym;
+
+ llvm_addr2line(filename, pc, &args->fileloc,
+ (unsigned int *)&args->line_nr, false, NULL);
+
+ dl = disasm_line__new(args);
+ if (dl == NULL)
+ goto err;
+
+ annotation_line__add(&dl->al, ¬es->src->source);
+
+ free(args->fileloc);
+ pc += ins_len;
+ offset += ins_len;
+ }
+
+ LLVMDisasmDispose(disasm);
+ free(buf);
+ free(line_storage);
+ return 0;
+
+err:
+ LLVMDisasmDispose(disasm);
+ free(buf);
+ free(line_storage);
+ return -1;
+}
+#endif
+
+
/*
* Possibly create a new version of line with tabs expanded. Returns the
* existing or new line, storage is updated if a new line is allocated. If
@@ -1730,6 +1920,11 @@ int symbol__disassemble(struct symbol *sym, struct annotate_args *args)
strcpy(symfs_filename, tmp);
}
+#ifdef HAVE_LLVM_SUPPORT
+ err = symbol__disassemble_llvm(symfs_filename, sym, args);
+ if (err == 0)
+ goto out_remove_tmp;
+#endif
#ifdef HAVE_LIBCAPSTONE_SUPPORT
err = symbol__disassemble_capstone(symfs_filename, sym, args);
if (err == 0)
diff --git a/tools/perf/util/llvm-c-helpers.cpp b/tools/perf/util/llvm-c-helpers.cpp
index cde3f1f03af0..4a34de7551f8 100644
--- a/tools/perf/util/llvm-c-helpers.cpp
+++ b/tools/perf/util/llvm-c-helpers.cpp
@@ -8,6 +8,7 @@
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-parameter" /* Needed for LLVM <= 15 */
#include <llvm/DebugInfo/Symbolize/Symbolize.h>
+#include <llvm/Support/TargetSelect.h>
#pragma GCC diagnostic pop
#include <stdio.h>
@@ -16,6 +17,9 @@
#include "symbol_conf.h"
#include "llvm-c-helpers.h"
+extern "C"
+char *dso__demangle_sym(struct dso *dso, int kmodule, const char *elf_name);
+
using namespace llvm;
using llvm::symbolize::LLVMSymbolizer;
@@ -128,3 +132,61 @@ int llvm_addr2line(const char *dso_name, u64 addr,
return extract_file_and_line(*res_or_err, file, line);
}
}
+
+static char *
+make_symbol_relative_string(struct dso *dso, const char *sym_name,
+ u64 addr, u64 base_addr)
+{
+ if (!strcmp(sym_name, "<invalid>"))
+ return NULL;
+
+ char *demangled = dso__demangle_sym(dso, 0, sym_name);
+ if (base_addr && base_addr != addr) {
+ char buf[256];
+ snprintf(buf, sizeof(buf), "%s+0x%lx",
+ demangled ? demangled : sym_name, addr - base_addr);
+ free(demangled);
+ return strdup(buf);
+ } else {
+ if (demangled)
+ return demangled;
+ else
+ return strdup(sym_name);
+ }
+}
+
+extern "C"
+char *llvm_name_for_code(struct dso *dso, const char *dso_name, u64 addr)
+{
+ LLVMSymbolizer *symbolizer = get_symbolizer();
+ object::SectionedAddress sectioned_addr = {
+ addr,
+ object::SectionedAddress::UndefSection
+ };
+ Expected<DILineInfo> res_or_err =
+ symbolizer->symbolizeCode(dso_name, sectioned_addr);
+ if (!res_or_err) {
+ return NULL;
+ }
+ return make_symbol_relative_string(
+ dso, res_or_err->FunctionName.c_str(),
+ addr, res_or_err->StartAddress.value_or(0));
+}
+
+extern "C"
+char *llvm_name_for_data(struct dso *dso, const char *dso_name, u64 addr)
+{
+ LLVMSymbolizer *symbolizer = get_symbolizer();
+ object::SectionedAddress sectioned_addr = {
+ addr,
+ object::SectionedAddress::UndefSection
+ };
+ Expected<DIGlobal> res_or_err =
+ symbolizer->symbolizeData(dso_name, sectioned_addr);
+ if (!res_or_err) {
+ return NULL;
+ }
+ return make_symbol_relative_string(
+ dso, res_or_err->Name.c_str(),
+ addr, res_or_err->Start);
+}
diff --git a/tools/perf/util/llvm-c-helpers.h b/tools/perf/util/llvm-c-helpers.h
index 1b28cdc9f9b7..e00e3f73a906 100644
--- a/tools/perf/util/llvm-c-helpers.h
+++ b/tools/perf/util/llvm-c-helpers.h
@@ -11,6 +11,8 @@
extern "C" {
#endif
+struct dso;
+
struct llvm_a2l_frame {
char *filename;
char *funcname;
@@ -40,6 +42,15 @@ int llvm_addr2line(const char *dso_name,
bool unwind_inlines,
struct llvm_a2l_frame **inline_frames);
+/*
+ * Simple symbolizers for addresses; will convert something like
+ * 0x12345 to "func+0x123". Will return NULL if no symbol was found.
+ *
+ * The returned value must be freed by the caller, with free().
+ */
+char *llvm_name_for_code(struct dso *dso, const char *dso_name, u64 addr);
+char *llvm_name_for_data(struct dso *dso, const char *dso_name, u64 addr);
+
#ifdef __cplusplus
}
#endif
--
2.43.0
Hello,
Thanks a lot for the patches!
On Mon, May 20, 2024 at 1:31 AM Steinar H. Gunderson <[email protected]> wrote:
>
> In addition to the existing support for libbfd and calling out to
> an external addr2line command, add support for using libllvm directly.
> This is both faster than libbfd, and can be enabled in distro builds
> (the LLVM license has an explicit provision for GPLv2 compatibility).
> Thus, it is set as the primary choice if available.
>
> As an example, running perf report on a medium-size profile with
> DWARF-based backtraces took 58 seconds with LLVM, 78 seconds with
> libbfd, 153 seconds with external llvm-addr2line, and I got tired
> and aborted the test after waiting for 55 minutes with external
> bfd addr2line (which is the default for perf as compiled by distributions
> today). Evidently, for this case, the bfd addr2line process needs
> 18 seconds (on a 5.2 GHz Zen 3) to load the .debug ELF in question,
> hits the 1-second timeout and gets killed during initialization,
> getting restarted anew every time. Having an in-process addr2line
> makes this much more robust.
>
> As future extensions, libllvm can be used in many other places where
> we currently use libbfd or other libraries:
>
> - Symbol enumeration (in particular, for PE binaries).
> - Demangling (including non-Itanium demangling, e.g. Microsoft
> or Rust).
> - Disassembling (perf annotate).
I think it should support other DWARF use cases like
unwinding and type info?
>
> However, these are much less pressing; most people don't profile
> PE binaries, and perf has non-bfd paths for ELF. The same with
> demangling; the default _cxa_demangle path works fine for most
> users. Disassembling is coming in a later patch in the series;
> however do note that while bfd objdump can be slow on large binaries,
> it is possible to use --objdump=llvm-objdump to get the speed benefits.
I remember bfd objdump is sometimes faster than llvm-objdump
especially when no line numbers are requested IIRC.
> (It appears LLVM-based demangling is very simple, should we want
> that.)
>
> Tested with LLVM 14, 15, 16, 18 and 19. For some reason, LLVM 12 was not
> correctly detected using feature_check, and thus was not tested.
Anyway, nice work. Maybe we can implement other use cases
using LLVM and reduce the dependencies.
Thanks,
Namhyung
>
> Signed-off-by: Steinar H. Gunderson <[email protected]>
On Wed, May 22, 2024 at 10:27:06AM -0700, Namhyung Kim wrote:
> I think it should support other DWARF use cases like
> unwinding and type info?
I don't actually know. I had a look, but could really only find
documentation for _writing_ DWARF info. However, I've hardly used LLVM
before, so it's entirely possible that I missed something.
> I remember bfd objdump is sometimes faster than llvm-objdump
> especially when no line numbers are requested IIRC.
Hm, I've never seen that. But it's impossible to say for sure
that no such case exists, of course.
> Anyway, nice work. Maybe we can implement other use cases
> using LLVM and reduce the dependencies.
It's possible to remove the libbfd dependency entirely if that's a goal,
at least, but I don't know what the current thinking is. I'll be happy
to take a stab at it (I guess it's possible to test the PE support with
WINE fairly easily?).
I found out that if compiling with an older compiler, LLVM changes to
llvm::Optional and doesn't have .value_or(), so I need to fix that
(the patch is trivial, but it means I need to post a v5, I guess).
Is there anything else I need to do after that to get this merged?
/* Steinar */
On Wed, May 22, 2024 at 12:50 PM Steinar H. Gunderson <sesse@googlecom> wrote:
>
> On Wed, May 22, 2024 at 10:27:06AM -0700, Namhyung Kim wrote:
> > I think it should support other DWARF use cases like
> > unwinding and type info?
>
> I don't actually know. I had a look, but could really only find
> documentation for _writing_ DWARF info. However, I've hardly used LLVM
> before, so it's entirely possible that I missed something.
Oh ok. I guess it should be able to read when it knows how to write. :)
But anyway they are separate, nice-to-have issues. I think we can
add them later.
>
> > I remember bfd objdump is sometimes faster than llvm-objdump
> > especially when no line numbers are requested IIRC.
>
> Hm, I've never seen that. But it's impossible to say for sure
> that no such case exists, of course.
>
> > Anyway, nice work. Maybe we can implement other use cases
> > using LLVM and reduce the dependencies.
>
> It's possible to remove the libbfd dependency entirely if that's a goal,
> at least, but I don't know what the current thinking is. I'll be happy
> to take a stab at it (I guess it's possible to test the PE support with
> WINE fairly easily?).
Great! Personally I found libbfd is hard to read (and use). Hope
that libllvm is better in that pov. I'm not sure if we all want to
remove the libbfd dependency but at least we can select one of
them at build time. Maybe the same for libelf and libdw(fl) too.
>
> I found out that if compiling with an older compiler, LLVM changes to
> llvm::Optional and doesn't have .value_or(), so I need to fix that
> (the patch is trivial, but it means I need to post a v5, I guess).
> Is there anything else I need to do after that to get this merged?
Having symbol enumeration and demangling with LLVM would
be nice but not required to merge this work. I'll take a deeper
look next week. Please post v5.
Thanks,
Namhyung
On Wed, May 22, 2024 at 01:46:35PM -0700, Namhyung Kim wrote:
> Great! Personally I found libbfd is hard to read (and use). Hope
> that libllvm is better in that pov. I'm not sure if we all want to
> remove the libbfd dependency but at least we can select one of
> them at build time. Maybe the same for libelf and libdw(fl) too.
I've never used either before, but I found libllvm pretty
straightforward. The C/C++ interop is a bit painful, though.
(The disassembler has a C interface, but addr2line does not,
from what I could see.)
> Having symbol enumeration and demangling with LLVM would
> be nice but not required to merge this work. I'll take a deeper
> look next week. Please post v5.
Posted.
/* Steinar */
On Mon, May 20, 2024 at 10:30:46AM +0200, Steinar H. Gunderson wrote:
> In addition to the existing support for libbfd and calling out to
> an external addr2line command, add support for using libllvm directly.
> This is both faster than libbfd, and can be enabled in distro builds
> (the LLVM license has an explicit provision for GPLv2 compatibility).
> Thus, it is set as the primary choice if available.
That is great news! Thanks for contributing this.
> As an example, running perf report on a medium-size profile with
> DWARF-based backtraces took 58 seconds with LLVM, 78 seconds with
> libbfd, 153 seconds with external llvm-addr2line, and I got tired
> and aborted the test after waiting for 55 minutes with external
> bfd addr2line (which is the default for perf as compiled by distributions
> today). Evidently, for this case, the bfd addr2line process needs
> 18 seconds (on a 5.2 GHz Zen 3) to load the .debug ELF in question,
> hits the 1-second timeout and gets killed during initialization,
> getting restarted anew every time. Having an in-process addr2line
> makes this much more robust.
>
> As future extensions, libllvm can be used in many other places where
> we currently use libbfd or other libraries:
>
> - Symbol enumeration (in particular, for PE binaries).
> - Demangling (including non-Itanium demangling, e.g. Microsoft
> or Rust).
> - Disassembling (perf annotate).
All great news.
> However, these are much less pressing; most people don't profile
> PE binaries, and perf has non-bfd paths for ELF. The same with
> demangling; the default _cxa_demangle path works fine for most
> users. Disassembling is coming in a later patch in the series;
> however do note that while bfd objdump can be slow on large binaries,
> it is possible to use --objdump=llvm-objdump to get the speed benefits.
> (It appears LLVM-based demangling is very simple, should we want
> that.)
>
> Tested with LLVM 14, 15, 16, 18 and 19. For some reason, LLVM 12 was not
> correctly detected using feature_check, and thus was not tested.
And here is an area that we need to have in mind when adding code like
this, that uses infrastructure that evolves over compiler versions and
in combination with the usage perf makes of it: We need to have 'perf
test' entries to compare the output of existing methods with the ones
from these new ones.
Its great having something we can enable by default so that distros pick
it, having the BFD one, we can keep it while it doesn't become too much
of a maintainance burden for us developers to test it against the
(new) default methods.
I'll try and test your patchkit, thanks again!
- Arnaldo
> Signed-off-by: Steinar H. Gunderson <[email protected]>
> ---
> tools/build/Makefile.feature | 1 +
> tools/perf/Makefile.config | 15 ++++
> tools/perf/builtin-version.c | 1 +
> tools/perf/util/Build | 1 +
> tools/perf/util/llvm-c-helpers.cpp | 130 +++++++++++++++++++++++++++++
> tools/perf/util/llvm-c-helpers.h | 47 +++++++++++
> tools/perf/util/srcline.c | 57 ++++++++++++-
> 7 files changed, 251 insertions(+), 1 deletion(-)
> create mode 100644 tools/perf/util/llvm-c-helpers.cpp
> create mode 100644 tools/perf/util/llvm-c-helpers.h
>
> diff --git a/tools/build/Makefile.feature b/tools/build/Makefile.feature
> index 1e2ab148d5db..278b26216254 100644
> --- a/tools/build/Makefile.feature
> +++ b/tools/build/Makefile.feature
> @@ -136,6 +136,7 @@ FEATURE_DISPLAY ?= \
> libunwind \
> libdw-dwarf-unwind \
> libcapstone \
> + llvm \
> zlib \
> lzma \
> get_cpuid \
> diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> index 7f1e016a9253..414a37f712bd 100644
> --- a/tools/perf/Makefile.config
> +++ b/tools/perf/Makefile.config
> @@ -969,6 +969,21 @@ ifdef BUILD_NONDISTRO
> endif
> endif
>
> +ifndef NO_LLVM
> + $(call feature_check,llvm)
> + ifeq ($(feature-llvm), 1)
> + CFLAGS += -DHAVE_LLVM_SUPPORT
> + CXXFLAGS += -DHAVE_LLVM_SUPPORT
> + CXXFLAGS += $(shell $(LLVM_CONFIG) --cxxflags)
> + LIBLLVM = $(shell $(LLVM_CONFIG) --libs all) $(shell $(LLVM_CONFIG) --system-libs)
> + EXTLIBS += -L$(shell $(LLVM_CONFIG) --libdir) $(LIBLLVM)
> + $(call detected,CONFIG_LLVM)
> + else
> + $(warning No libllvm found, slower source file resolution, please install llvm-devel/llvm-dev)
> + NO_LLVM := 1
> + endif
> +endif
> +
> ifndef NO_DEMANGLE
> $(call feature_check,cxa-demangle)
> ifeq ($(feature-cxa-demangle), 1)
> diff --git a/tools/perf/builtin-version.c b/tools/perf/builtin-version.c
> index 398aa53e9e2e..94d8e13a688f 100644
> --- a/tools/perf/builtin-version.c
> +++ b/tools/perf/builtin-version.c
> @@ -65,6 +65,7 @@ static void library_status(void)
> STATUS(HAVE_LIBBFD_SUPPORT, libbfd);
> STATUS(HAVE_DEBUGINFOD_SUPPORT, debuginfod);
> STATUS(HAVE_LIBELF_SUPPORT, libelf);
> + STATUS(HAVE_LLVM_SUPPORT, libllvm);
> STATUS(HAVE_LIBNUMA_SUPPORT, libnuma);
> STATUS(HAVE_LIBNUMA_SUPPORT, numa_num_possible_cpus);
> STATUS(HAVE_LIBPERL_SUPPORT, libperl);
> diff --git a/tools/perf/util/Build b/tools/perf/util/Build
> index da64efd8718f..32c4e5e634ed 100644
> --- a/tools/perf/util/Build
> +++ b/tools/perf/util/Build
> @@ -226,6 +226,7 @@ perf-$(CONFIG_CXX_DEMANGLE) += demangle-cxx.o
> perf-y += demangle-ocaml.o
> perf-y += demangle-java.o
> perf-y += demangle-rust.o
> +perf-$(CONFIG_LLVM) += llvm-c-helpers.o
>
> ifdef CONFIG_JITDUMP
> perf-$(CONFIG_LIBELF) += jitdump.o
> diff --git a/tools/perf/util/llvm-c-helpers.cpp b/tools/perf/util/llvm-c-helpers.cpp
> new file mode 100644
> index 000000000000..cde3f1f03af0
> --- /dev/null
> +++ b/tools/perf/util/llvm-c-helpers.cpp
> @@ -0,0 +1,130 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +/*
> + * Must come before the linux/compiler.h include, which defines several
> + * macros (e.g. noinline) that conflict with compiler builtins used
> + * by LLVM.
> + */
> +#pragma GCC diagnostic push
> +#pragma GCC diagnostic ignored "-Wunused-parameter" /* Needed for LLVM <= 15 */
> +#include <llvm/DebugInfo/Symbolize/Symbolize.h>
> +#pragma GCC diagnostic pop
> +
> +#include <stdio.h>
> +#include <sys/types.h>
> +#include <linux/compiler.h>
> +#include "symbol_conf.h"
> +#include "llvm-c-helpers.h"
> +
> +using namespace llvm;
> +using llvm::symbolize::LLVMSymbolizer;
> +
> +/*
> + * Allocate a static LLVMSymbolizer, which will live to the end of the program.
> + * Unlike the bfd paths, LLVMSymbolizer has its own cache, so we do not need
> + * to store anything in the dso struct.
> + */
> +static LLVMSymbolizer *get_symbolizer()
> +{
> + static LLVMSymbolizer *instance = nullptr;
> + if (instance == nullptr) {
> + LLVMSymbolizer::Options opts;
> + /*
> + * LLVM sometimes demangles slightly different from the rest
> + * of the code, and this mismatch can cause new_inline_sym()
> + * to get confused and mark non-inline symbol as inlined
> + * (since the name does not properly match up with base_sym).
> + * Thus, disable the demangling and let the rest of the code
> + * handle it.
> + */
> + opts.Demangle = false;
> + instance = new LLVMSymbolizer(opts);
> + }
> + return instance;
> +}
> +
> +/* Returns 0 on error, 1 on success. */
> +static int extract_file_and_line(const DILineInfo& line_info, char **file,
> + unsigned int *line)
> +{
> + if (file) {
> + if (line_info.FileName == "<invalid>") {
> + /* Match the convention of libbfd. */
> + *file = nullptr;
> + } else {
> + /* The caller expects to get something it can free(). */
> + *file = strdup(line_info.FileName.c_str());
> + if (*file == nullptr)
> + return 0;
> + }
> + }
> + if (line)
> + *line = line_info.Line;
> + return 1;
> +}
> +
> +extern "C"
> +int llvm_addr2line(const char *dso_name, u64 addr,
> + char **file, unsigned int *line,
> + bool unwind_inlines,
> + llvm_a2l_frame** inline_frames)
> +{
> + LLVMSymbolizer *symbolizer = get_symbolizer();
> + object::SectionedAddress sectioned_addr = {
> + addr,
> + object::SectionedAddress::UndefSection
> + };
> +
> + if (unwind_inlines) {
> + Expected<DIInliningInfo> res_or_err =
> + symbolizer->symbolizeInlinedCode(dso_name,
> + sectioned_addr);
> + if (!res_or_err)
> + return 0;
> + unsigned num_frames = res_or_err->getNumberOfFrames();
> + if (num_frames == 0)
> + return 0;
> +
> + if (extract_file_and_line(
> + res_or_err->getFrame(0), file, line) == 0)
> + return 0;
> +
> + *inline_frames = (llvm_a2l_frame*)malloc(
> + sizeof(**inline_frames) * num_frames);
> + if (*inline_frames == nullptr)
> + return 0;
> +
> + for (unsigned i = 0; i < num_frames; ++i) {
> + const DILineInfo& src = res_or_err->getFrame(i);
> + llvm_a2l_frame& dst = (*inline_frames)[i];
> + if (src.FileName == "<invalid>")
> + /* Match the convention of libbfd. */
> + dst.filename = nullptr;
> + else
> + dst.filename = strdup(src.FileName.c_str());
> + dst.funcname = strdup(src.FunctionName.c_str());
> + dst.line = src.Line;
> +
> + if (dst.filename == nullptr ||
> + dst.funcname == nullptr) {
> + for (unsigned j = 0; j <= i; ++j) {
> + free((*inline_frames)[j].filename);
> + free((*inline_frames)[j].funcname);
> + }
> + free(*inline_frames);
> + return 0;
> + }
> + }
> +
> + return num_frames;
> + } else {
> + if (inline_frames)
> + *inline_frames = nullptr;
> +
> + Expected<DILineInfo> res_or_err =
> + symbolizer->symbolizeCode(dso_name, sectioned_addr);
> + if (!res_or_err)
> + return 0;
> + return extract_file_and_line(*res_or_err, file, line);
> + }
> +}
> diff --git a/tools/perf/util/llvm-c-helpers.h b/tools/perf/util/llvm-c-helpers.h
> new file mode 100644
> index 000000000000..1b28cdc9f9b7
> --- /dev/null
> +++ b/tools/perf/util/llvm-c-helpers.h
> @@ -0,0 +1,47 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __PERF_LLVM_C_HELPERS
> +#define __PERF_LLVM_C_HELPERS 1
> +
> +/*
> + * Helpers to call into LLVM C++ code from C, for the parts that do not have
> + * C APIs.
> + */
> +
> +#ifdef __cplusplus
> +extern "C" {
> +#endif
> +
> +struct llvm_a2l_frame {
> + char *filename;
> + char *funcname;
> + unsigned int line;
> +};
> +
> +/*
> + * Implement addr2line() using libLLVM. LLVM is a C++ API, and
> + * many of the linux/ headers cannot be included in a C++ compile unit,
> + * so we need to make a little bridge code here. llvm_addr2line() will
> + * convert the inline frame information from LLVM's internal structures
> + * and put them into a flat array given in inline_frames. The caller
> + * is then responsible for taking that array and convert it into perf's
> + * regular inline frame structures (which depend on e.g. struct list_head).
> + *
> + * If the address could not be resolved, or an error occurred (e.g. OOM),
> + * returns 0. Otherwise, returns the number of inline frames (which means 1
> + * if the address was not part of an inlined function). If unwind_inlines
> + * is set and the return code is nonzero, inline_frames will be set to
> + * a newly allocated array with that length. The caller is then responsible
> + * for freeing both the strings and the array itself.
> + */
> +int llvm_addr2line(const char *dso_name,
> + u64 addr,
> + char **file,
> + unsigned int *line,
> + bool unwind_inlines,
> + struct llvm_a2l_frame **inline_frames);
> +
> +#ifdef __cplusplus
> +}
> +#endif
> +
> +#endif /* __PERF_LLVM_C_HELPERS */
> diff --git a/tools/perf/util/srcline.c b/tools/perf/util/srcline.c
> index 9d670d8c1c08..0505b4c16608 100644
> --- a/tools/perf/util/srcline.c
> +++ b/tools/perf/util/srcline.c
> @@ -16,6 +16,9 @@
> #include "util/debug.h"
> #include "util/callchain.h"
> #include "util/symbol_conf.h"
> +#ifdef HAVE_LLVM_SUPPORT
> +#include "util/llvm-c-helpers.h"
> +#endif
> #include "srcline.h"
> #include "string2.h"
> #include "symbol.h"
> @@ -130,7 +133,59 @@ static struct symbol *new_inline_sym(struct dso *dso,
>
> #define MAX_INLINE_NEST 1024
>
> -#ifdef HAVE_LIBBFD_SUPPORT
> +#ifdef HAVE_LLVM_SUPPORT
> +
> +static void free_llvm_inline_frames(struct llvm_a2l_frame *inline_frames,
> + int num_frames)
> +{
> + if (inline_frames != NULL) {
> + for (int i = 0; i < num_frames; ++i) {
> + free(inline_frames[i].filename);
> + free(inline_frames[i].funcname);
> + }
> + free(inline_frames);
> + }
> +}
> +
> +static int addr2line(const char *dso_name, u64 addr,
> + char **file, unsigned int *line, struct dso *dso,
> + bool unwind_inlines, struct inline_node *node,
> + struct symbol *sym)
> +{
> + struct llvm_a2l_frame *inline_frames = NULL;
> + int num_frames = llvm_addr2line(dso_name, addr, file, line,
> + node && unwind_inlines, &inline_frames);
> +
> + if (num_frames == 0 || !inline_frames) {
> + /* Error, or we didn't want inlines. */
> + return num_frames;
> + }
> +
> + for (int i = 0; i < num_frames; ++i) {
> + struct symbol *inline_sym =
> + new_inline_sym(dso, sym, inline_frames[i].funcname);
> + char *srcline = NULL;
> +
> + if (inline_frames[i].filename)
> + srcline = srcline_from_fileline(
> + inline_frames[i].filename,
> + inline_frames[i].line);
> + if (inline_list__append(inline_sym, srcline, node) != 0) {
> + free_llvm_inline_frames(inline_frames, num_frames);
> + return 0;
> + }
> + }
> + free_llvm_inline_frames(inline_frames, num_frames);
> +
> + return num_frames;
> +}
> +
> +void dso__free_a2l(struct dso *)
> +{
> + /* Nothing to free. */
> +}
> +
> +#elif defined(HAVE_LIBBFD_SUPPORT)
>
> /*
> * Implement addr2line using libbfd.
> --
> 2.43.0