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

Split from #100596.

Introduce the RealtimeSanitizer transform, which inserts the
rtsan_enter/exit functions at the appropriate places in an instrumented
function.

Author: cjappl

llvm/include/llvm/Transforms/Instrumentation/RealtimeSanitizer.h

@@ -0,0 +1,41 @@
+//===- RealtimeSanitizer.h - 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.
+//
+// The instrumentation pass inserts calls to __rtsan_realtime_enter and
+// __rtsan_realtime_exit at the entry and exit points of functions that are
+// marked with the appropriate attribute.
+//
+// See also: llvm-project/compiler-rt/lib/rtsan/
+//
+//===----------------------------------------------------------------------===//
+#ifndef LLVM_TRANSFORMS_INSTRUMENTATION_REALTIMESANITIZER_H
+#define LLVM_TRANSFORMS_INSTRUMENTATION_REALTIMESANITIZER_H
+
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+struct RealtimeSanitizerOptions {};
+
+class RealtimeSanitizerPass : public PassInfoMixin<RealtimeSanitizerPass> {
+public:
+  RealtimeSanitizerPass(const RealtimeSanitizerOptions &Options);
+  PreservedAnalyses run(Function &F, AnalysisManager<Function> &AM);
+
+  static bool isRequired() { return true; }
+
+private:
+  RealtimeSanitizerOptions Options{};
+};
+
+} // namespace llvm
+
+#endif // LLVM_TRANSFORMS_INSTRUMENTATION_REALTIMESANITIZER_H

llvm/lib/Passes/PassBuilder.cpp

@@ -199,6 +199,7 @@
 #include "llvm/Transforms/Instrumentation/PGOForceFunctionAttrs.h"
 #include "llvm/Transforms/Instrumentation/PGOInstrumentation.h"
 #include "llvm/Transforms/Instrumentation/PoisonChecking.h"
+#include "llvm/Transforms/Instrumentation/RealtimeSanitizer.h"
 #include "llvm/Transforms/Instrumentation/SanitizerBinaryMetadata.h"
 #include "llvm/Transforms/Instrumentation/SanitizerCoverage.h"
 #include "llvm/Transforms/Instrumentation/ThreadSanitizer.h"
@@ -1210,6 +1211,11 @@ parseRegAllocFastPassOptions(PassBuilder &PB, StringRef Params) {
   return Opts;
 }
 
+Expected<RealtimeSanitizerOptions> parseRtSanPassOptions(StringRef Params) {
+  RealtimeSanitizerOptions Result;
+  return Result;
+}
+
 } // namespace
 
 /// Tests whether a pass name starts with a valid prefix for a default pipeline

llvm/lib/Passes/PassRegistry.def

@@ -592,6 +592,10 @@ FUNCTION_PASS_WITH_PARAMS(
       return WinEHPreparePass(DemoteCatchSwitchPHIOnly);
     },
     parseWinEHPrepareOptions, "demote-catchswitch-only")
+FUNCTION_PASS_WITH_PARAMS(
+    "rtsan", "RealtimeSanitizerPass",
+    [](RealtimeSanitizerOptions Opts) { return RealtimeSanitizerPass(Opts); },
+    parseRtSanPassOptions, "")
 #undef FUNCTION_PASS_WITH_PARAMS
 
 #ifndef LOOPNEST_PASS

llvm/lib/Transforms/Instrumentation/CMakeLists.txt

@@ -25,6 +25,7 @@ add_llvm_component_library(LLVMInstrumentation
   ValueProfileCollector.cpp
   ThreadSanitizer.cpp
   HWAddressSanitizer.cpp
+  RealtimeSanitizer.cpp
 
   ADDITIONAL_HEADER_DIRS
   ${LLVM_MAIN_INCLUDE_DIR}/llvm/Transforms

llvm/lib/Transforms/Instrumentation/RealtimeSanitizer.cpp

@@ -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();
+  }
+
+  return PreservedAnalyses::all();
+}

llvm/test/Instrumentation/RealtimeSanitizer/rtsan.ll

@@ -0,0 +1,27 @@
+; RUN: opt < %s -passes=rtsan -S | FileCheck %s
+
+define void @violation() #0 {
+  %1 = alloca ptr, align 8
+  %2 = call ptr @malloc(i64 noundef 2) #3
+  store ptr %2, ptr %1, align 8
+  ret void
+}
+
+declare ptr @malloc(i64 noundef) #1
+
+define noundef i32 @main() #2 {
+  %1 = alloca i32, align 4
+  store i32 0, ptr %1, align 4
+  call void @violation() #4
+  ret i32 0
+}
+
+attributes #0 = { mustprogress noinline sanitize_realtime optnone ssp uwtable(sync) }
+
+; RealtimeSanitizer pass should insert __rtsan_realtime_enter right after function definition
+; CHECK-LABEL: @violation()
+; CHECK-NEXT: call{{.*}}@__rtsan_realtime_enter
+
+; RealtimeSanitizer pass should insert __rtsan_realtime_exit right before function return
+; CHECK: call{{.*}}@__rtsan_realtime_exit
+; CHECK-NEXT: ret{{.*}}void

llvm/test/Instrumentation/RealtimeSanitizer/rtsan_multi_return.ll

@@ -0,0 +1,30 @@
+; RUN: opt < %s -passes=rtsan -S | FileCheck %s
+
+define i32 @example(i32 %x) #0 {
+entry:
+    %retval = alloca i32
+    %cmp = icmp sgt i32 %x, 10
+    br i1 %cmp, label %then, label %else
+
+then:
+    ret i32 1
+
+else:
+    ret i32 0
+}
+
+attributes #0 = { mustprogress noinline sanitize_realtime optnone ssp uwtable(sync) }
+
+; RealtimeSanitizer pass should insert __rtsan_realtime_enter right after function definition
+; CHECK-LABEL: @example(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: call{{.*}}@__rtsan_realtime_enter
+
+; RealtimeSanitizer pass should insert the call at both function returns
+; CHECK-LABEL: then:
+; CHECK-NEXT: call{{.*}}@__rtsan_realtime_exit
+; CHECK-NEXT: ret i32 1
+
+; CHECK-LABEL: else:
+; CHECK-NEXT: call{{.*}}@__rtsan_realtime_exit
+; CHECK-NEXT: ret i32 0