[llvm] llvm-profgen: Fix race condition (PR #83489)

[Matthias Braun via llvm-commits]

https://github.com/MatzeB created https://github.com/llvm/llvm-project/pull/83489

Fix race condition when multiple instances of `llvm-progen` read from the same 
inputs.


>From 3683e6d17d6af1925b38b1fafdc2e1474f2e7995 Mon Sep 17 00:00:00 2001
From: Matthias Braun <matze at braunis.de>
Date: Thu, 29 Feb 2024 13:51:47 -0800
Subject: [PATCH] llvm-profgen: Fix race condition

---
 llvm/tools/llvm-profgen/PerfReader.cpp | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/llvm/tools/llvm-profgen/PerfReader.cpp b/llvm/tools/llvm-profgen/PerfReader.cpp
index 313d40483a2591..df952734fbf939 100644
--- a/llvm/tools/llvm-profgen/PerfReader.cpp
+++ b/llvm/tools/llvm-profgen/PerfReader.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 #include "PerfReader.h"
 #include "ProfileGenerator.h"
+#include "llvm/ADT/SmallString.h"
 #include "llvm/DebugInfo/Symbolize/SymbolizableModule.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Process.h"
@@ -361,8 +362,11 @@ PerfScriptReader::convertPerfDataToTrace(ProfiledBinary *Binary,
     exitWithError("Perf not found.");
   }
   std::string PerfPath = *PerfExecutable;
-  std::string PerfTraceFile = PerfData.str() + ".script.tmp";
-  std::string ErrorFile = PerfData.str() + ".script.err.tmp";
+
+  SmallString<128> PerfTraceFile;
+  sys::fs::createUniquePath("perf-script-%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%.tmp",
+                            PerfTraceFile, /*MakeAbsolute=*/true);
+  std::string ErrorFile = std::string(PerfTraceFile) + ".script.err.tmp";
   StringRef ScriptMMapArgs[] = {PerfPath, "script",   "--show-mmap-events",
                                 "-F",     "comm,pid", "-i",
                                 PerfData};
@@ -400,7 +404,8 @@ PerfScriptReader::convertPerfDataToTrace(ProfiledBinary *Binary,
                                   PIDs,     "-i",         PerfData};
   sys::ExecuteAndWait(PerfPath, ScriptSampleArgs, std::nullopt, Redirects);
 
-  return {PerfTraceFile, PerfFormat::PerfScript, PerfContent::UnknownContent};
+  return {std::string(PerfTraceFile), PerfFormat::PerfScript,
+          PerfContent::UnknownContent};
 }
 
 void PerfScriptReader::updateBinaryAddress(const MMapEvent &Event) {