[llvm] [tools][llc] Add `--save-stats` option (PR #163967)
Tomer Shafir via llvm-commits
llvm-commits at lists.llvm.org
Mon Oct 20 05:04:55 PDT 2025
https://github.com/tomershafir updated https://github.com/llvm/llvm-project/pull/163967
>From 56a0157a1a511e8b29eb8b90e9e5cf480d2d36aa Mon Sep 17 00:00:00 2001
From: tomershafir <tomer.shafir8 at gmail.com>
Date: Fri, 17 Oct 2025 16:46:06 +0300
Subject: [PATCH] [tools][llc] Add `--save-stats` option
This patch adds a Clang-compatible `--save-stats` option, to provide an easy to use way to save LLVM statistics files when working with llc on the backend.
Like on Clang, one can specify `--save-stats`, `--save-stats=cwd`, and `--save-stats=obj` with the same semantics and JSON format.
The implementation uses 2 methods `MaybeEnableStats` and `MaybeSaveStats` called before and after `compileModule` respectively that externally own the statistics related logic, while `compileModule` is now required to return the resolved output filename via an output param.
Note: like on Clang, the pre-existing `--stats` option is not affected.
---
llvm/docs/CommandGuide/llc.rst | 6 +++
llvm/docs/ReleaseNotes.md | 1 +
llvm/test/tools/llc/save-stats.ll | 10 +++++
llvm/tools/llc/llc.cpp | 72 +++++++++++++++++++++++++++++--
4 files changed, 85 insertions(+), 4 deletions(-)
create mode 100644 llvm/test/tools/llc/save-stats.ll
diff --git a/llvm/docs/CommandGuide/llc.rst b/llvm/docs/CommandGuide/llc.rst
index 900649f59c401..6fe0a51292132 100644
--- a/llvm/docs/CommandGuide/llc.rst
+++ b/llvm/docs/CommandGuide/llc.rst
@@ -136,6 +136,12 @@ End-user Options
Print statistics recorded by code-generation passes.
+.. option:: --save-stats, --save-stats=cwd, --save-stats=obj
+
+ Save LLVM statistics to a file in the current directory
+ (:option:`--save-stats`/"--save-stats=cwd") or the directory
+ of the output file ("--save-stats=obj") in JSON format.
+
.. option:: --time-passes
Record the amount of time needed for each pass and print a report to standard
diff --git a/llvm/docs/ReleaseNotes.md b/llvm/docs/ReleaseNotes.md
index 754cd409f83eb..66a0986210820 100644
--- a/llvm/docs/ReleaseNotes.md
+++ b/llvm/docs/ReleaseNotes.md
@@ -175,6 +175,7 @@ Changes to the LLVM tools
* `llvm-readelf` now dumps all hex format values in lower-case mode.
* Some code paths for supporting Python 2.7 in `llvm-lit` have been removed.
* Support for `%T` in lit has been removed.
+* Add `--save-stats` option to `llc` to save LLVM statistics to a file. Compatible with the Clang option.
Changes to LLDB
---------------------------------
diff --git a/llvm/test/tools/llc/save-stats.ll b/llvm/test/tools/llc/save-stats.ll
new file mode 100644
index 0000000000000..cf0752c2c9eef
--- /dev/null
+++ b/llvm/test/tools/llc/save-stats.ll
@@ -0,0 +1,10 @@
+
+; RUN: rm -f %t.stats && llc -mtriple=arm64-apple-macosx --save-stats=obj -o %t.s %s && test -f %t.stats
+; RUN: rm -f %{t:stem}.tmp.stats && llc -mtriple=arm64-apple-macosx --save-stats=cwd -o %t.s %s && test -f %{t:stem}.tmp.stats
+; RUN: rm -f %{t:stem}.tmp.stats && llc -mtriple=arm64-apple-macosx --save-stats -o %t.s %s && test -f %{t:stem}.tmp.stats
+; RUN: not llc -mtriple=arm64-apple-macosx --save-stats=invalid -o %t.s %s 2>&1 | FileCheck %s --check-prefix=INVALID_ARG
+
+; INVALID_ARG: llc: error: Invalid --save-stats value: invalid, must be empty, 'cwd' or 'obj'
+define i32 @func() {
+ ret i32 0
+}
diff --git a/llvm/tools/llc/llc.cpp b/llvm/tools/llc/llc.cpp
index 8b03db301424b..7057c3f6c0254 100644
--- a/llvm/tools/llc/llc.cpp
+++ b/llvm/tools/llc/llc.cpp
@@ -15,6 +15,7 @@
#include "NewPMDriver.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/ScopeExit.h"
+#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/CodeGen/CommandFlags.h"
#include "llvm/CodeGen/LinkAllAsmWriterComponents.h"
@@ -45,6 +46,7 @@
#include "llvm/Support/FormattedStream.h"
#include "llvm/Support/InitLLVM.h"
#include "llvm/Support/PGOOptions.h"
+#include "llvm/Support/Path.h"
#include "llvm/Support/PluginLoader.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/TargetSelect.h"
@@ -57,6 +59,7 @@
#include "llvm/TargetParser/SubtargetFeature.h"
#include "llvm/TargetParser/Triple.h"
#include "llvm/Transforms/Utils/Cloning.h"
+#include <cassert>
#include <memory>
#include <optional>
using namespace llvm;
@@ -203,6 +206,13 @@ static cl::opt<std::string> RemarksFormat(
cl::desc("The format used for serializing remarks (default: YAML)"),
cl::value_desc("format"), cl::init("yaml"));
+static cl::opt<std::string> SaveStats(
+ "save-stats",
+ cl::desc("Save LLVM statistics to a file in the current directory"
+ "(`-save-stats`/`-save-stats=cwd`) or the directory of the output"
+ "file (`-save-stats=obj`). (default: cwd)"),
+ cl::init(""), cl::ValueOptional);
+
static cl::opt<bool> EnableNewPassManager(
"enable-new-pm", cl::desc("Enable the new pass manager"), cl::init(false));
@@ -276,7 +286,8 @@ static void setPGOOptions(TargetMachine &TM) {
TM.setPGOOption(PGOOpt);
}
-static int compileModule(char **, LLVMContext &);
+static int compileModule(char **argv, LLVMContext &Context,
+ std::string &OutputFilename);
[[noreturn]] static void reportError(Twine Msg, StringRef Filename = "") {
SmallString<256> Prefix;
@@ -355,6 +366,50 @@ static std::unique_ptr<ToolOutputFile> GetOutputStream(const char *TargetName,
return FDOut;
}
+static int MaybeEnableStats() {
+ if (SaveStats.getNumOccurrences() > 0) {
+ if (SaveStats.empty() || SaveStats == "cwd" || SaveStats == "obj") {
+ llvm::EnableStatistics(false);
+ } else {
+ WithColor::error(errs(), "llc")
+ << "Invalid --save-stats value: " << SaveStats
+ << ", must be empty, 'cwd' or 'obj'\n";
+ return 1;
+ }
+ }
+ return 0;
+}
+
+static int MaybeSaveStats(std::string &&OutputFilename) {
+ if (SaveStats.getNumOccurrences() > 0) {
+ SmallString<128> StatsFilename;
+ if (SaveStats == "obj") {
+ StatsFilename = OutputFilename;
+ llvm::sys::path::remove_filename(StatsFilename);
+ } else {
+ assert((SaveStats.empty() || SaveStats == "cwd") &&
+ "Should have been a valid --save-stats value");
+ }
+
+ auto BaseName = llvm::sys::path::filename(OutputFilename);
+ llvm::sys::path::append(StatsFilename, BaseName);
+ llvm::sys::path::replace_extension(StatsFilename, "stats");
+
+ auto FileFlags = llvm::sys::fs::OF_TextWithCRLF;
+ std::error_code EC;
+ auto StatsOS =
+ std::make_unique<llvm::raw_fd_ostream>(StatsFilename, EC, FileFlags);
+ if (EC) {
+ WithColor::error(errs(), "llc")
+ << "Unable to open statistics file: " << EC.message() << "\n";
+ return 1;
+ } else {
+ llvm::PrintStatisticsJSON(*StatsOS);
+ }
+ }
+ return 0;
+}
+
// main - Entry point for the llc compiler.
//
int main(int argc, char **argv) {
@@ -432,18 +487,23 @@ int main(int argc, char **argv) {
reportError(std::move(E), RemarksFilename);
LLVMRemarkFileHandle RemarksFile = std::move(*RemarksFileOrErr);
+ if (int RetVal = MaybeEnableStats())
+ return RetVal;
+ std::string OutputFilename;
+
if (InputLanguage != "" && InputLanguage != "ir" && InputLanguage != "mir")
reportError("input language must be '', 'IR' or 'MIR'");
// Compile the module TimeCompilations times to give better compile time
// metrics.
for (unsigned I = TimeCompilations; I; --I)
- if (int RetVal = compileModule(argv, Context))
+ if (int RetVal = compileModule(argv, Context, OutputFilename))
return RetVal;
if (RemarksFile)
RemarksFile->keep();
- return 0;
+
+ return MaybeSaveStats(std::move(OutputFilename));
}
static bool addPass(PassManagerBase &PM, const char *argv0, StringRef PassName,
@@ -475,7 +535,8 @@ static bool addPass(PassManagerBase &PM, const char *argv0, StringRef PassName,
return false;
}
-static int compileModule(char **argv, LLVMContext &Context) {
+static int compileModule(char **argv, LLVMContext &Context,
+ std::string &OutputFilename) {
// Load the module to be compiled...
SMDiagnostic Err;
std::unique_ptr<Module> M;
@@ -659,6 +720,9 @@ static int compileModule(char **argv, LLVMContext &Context) {
// Ensure the filename is passed down to CodeViewDebug.
Target->Options.ObjectFilenameForDebug = Out->outputFilename();
+ // Return a copy of the output filename via the output param
+ OutputFilename = Out->outputFilename();
+
// Tell target that this tool is not necessarily used with argument ABI
// compliance (i.e. narrow integer argument extensions).
Target->Options.VerifyArgABICompliance = 0;
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