[llvm] [LLVM][rtsan] Add RealtimeSanitizer transform pass (PR #101232)

[Florian Mayer via llvm-commits]

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@@ -0,0 +1,61 @@
+//===- RealtimeSanitizer.cpp - RealtimeSanitizer instrumentation *- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of the RealtimeSanitizer, an LLVM transformation for
+// detecting and reporting realtime safety violations.
+//
+// See also: llvm-project/compiler-rt/lib/rtsan/
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/IR/Analysis.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/Module.h"
+
+#include "llvm/Transforms/Instrumentation/RealtimeSanitizer.h"
+
+using namespace llvm;
+
+static void insertCallBeforeInstruction(Function &Fn, Instruction &Instruction,
+                                        const char *FunctionName) {
+  LLVMContext &Context = Fn.getContext();
+  FunctionType *FuncType = FunctionType::get(Type::getVoidTy(Context), false);
+  FunctionCallee Func =
+      Fn.getParent()->getOrInsertFunction(FunctionName, FuncType);
+  IRBuilder<> Builder{&Instruction};
+  Builder.CreateCall(Func, {});
+}
+
+static void insertCallAtFunctionEntryPoint(Function &Fn,
+                                           const char *InsertFnName) {
+
+  insertCallBeforeInstruction(Fn, Fn.front().front(), InsertFnName);
+}
+
+static void insertCallAtAllFunctionExitPoints(Function &Fn,
+                                              const char *InsertFnName) {
+  for (auto &BB : Fn)
+    for (auto &I : BB)
+      if (auto *RI = dyn_cast<ReturnInst>(&I))
+        insertCallBeforeInstruction(Fn, I, InsertFnName);
+}
+
+RealtimeSanitizerPass::RealtimeSanitizerPass(
+    const RealtimeSanitizerOptions &Options)
+    : Options{Options} {}
+
+PreservedAnalyses RealtimeSanitizerPass::run(Function &F,
+                                             AnalysisManager<Function> &AM) {
+  if (F.hasFnAttribute(Attribute::SanitizeRealtime)) {
+    insertCallAtFunctionEntryPoint(F, "__rtsan_realtime_enter");
+    insertCallAtAllFunctionExitPoints(F, "__rtsan_realtime_exit");
+    return PreservedAnalyses::none();
----------------
fmayer wrote:

It means whether the analysis has to be re-evalulated after the pass (if needed by a pass afterwards), or whether the pass has not changed the result (or, for some analyses, it is possible to incrementally change them, in which case it could also have done that).

https://github.com/llvm/llvm-project/pull/101232