https://github.com/cjappl updated
https://github.com/llvm/llvm-project/pull/102622
>From 9d3d49fa755c28b21c3b4771faae65cf418dec5a Mon Sep 17 00:00:00 2001
From: Chris Apple <cja-priv...@pm.me>
Date: Wed, 24 Jul 2024 14:25:44 -0700
Subject: [PATCH 1/3] [clang][rtsan] Introduce realtime sanitizer codegen and
driver
---
clang/include/clang/Basic/Sanitizers.def | 3 ++
clang/include/clang/Driver/SanitizerArgs.h | 1 +
clang/lib/CodeGen/BackendUtil.cpp | 8 ++++
clang/lib/CodeGen/CodeGenFunction.cpp | 6 +++
clang/lib/Driver/SanitizerArgs.cpp | 14 ++++--
clang/lib/Driver/ToolChains/CommonArgs.cpp | 6 +++
clang/lib/Driver/ToolChains/Darwin.cpp | 8 ++++
clang/lib/Driver/ToolChains/Linux.cpp | 1 +
clang/test/CodeGen/rtsan_attribute_inserted.c | 7 +++
clang/test/CodeGen/rtsan_insert_at_entry.c | 9 ++++
clang/test/CodeGen/rtsan_insert_at_exit.c | 9 ++++
.../rtsan_no_attribute_sanitizer_disabled.c | 8 ++++
clang/test/Driver/fsanitize.c | 46 +++++++++++++++++++
clang/test/Driver/rtsan.c | 14 ++++++
14 files changed, 135 insertions(+), 5 deletions(-)
create mode 100644 clang/test/CodeGen/rtsan_attribute_inserted.c
create mode 100644 clang/test/CodeGen/rtsan_insert_at_entry.c
create mode 100644 clang/test/CodeGen/rtsan_insert_at_exit.c
create mode 100644 clang/test/CodeGen/rtsan_no_attribute_sanitizer_disabled.c
create mode 100644 clang/test/Driver/rtsan.c
diff --git a/clang/include/clang/Basic/Sanitizers.def
b/clang/include/clang/Basic/Sanitizers.def
index bee35e9dca7c39..9223f62b3639a7 100644
--- a/clang/include/clang/Basic/Sanitizers.def
+++ b/clang/include/clang/Basic/Sanitizers.def
@@ -79,6 +79,9 @@ SANITIZER("thread", Thread)
// Numerical stability sanitizer.
SANITIZER("numerical", NumericalStability)
+// RealtimeSanitizer
+SANITIZER("realtime", Realtime)
+
// LeakSanitizer
SANITIZER("leak", Leak)
diff --git a/clang/include/clang/Driver/SanitizerArgs.h
b/clang/include/clang/Driver/SanitizerArgs.h
index 47ef175302679f..c13a640268f0c7 100644
--- a/clang/include/clang/Driver/SanitizerArgs.h
+++ b/clang/include/clang/Driver/SanitizerArgs.h
@@ -106,6 +106,7 @@ class SanitizerArgs {
bool needsNsanRt() const {
return Sanitizers.has(SanitizerKind::NumericalStability);
}
+ bool needsRtsanRt() const { return Sanitizers.has(SanitizerKind::Realtime); }
bool hasMemTag() const {
return hasMemtagHeap() || hasMemtagStack() || hasMemtagGlobals();
diff --git a/clang/lib/CodeGen/BackendUtil.cpp
b/clang/lib/CodeGen/BackendUtil.cpp
index 81e6702d5de666..95aa328c0245de 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -78,6 +78,7 @@
#include "llvm/Transforms/Instrumentation/MemorySanitizer.h"
#include "llvm/Transforms/Instrumentation/NumericalStabilitySanitizer.h"
#include "llvm/Transforms/Instrumentation/PGOInstrumentation.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"
@@ -989,6 +990,13 @@ void EmitAssemblyHelper::RunOptimizationPipeline(
FPM.addPass(BoundsCheckingPass());
});
+ if (LangOpts.Sanitize.has(SanitizerKind::Realtime))
+ PB.registerScalarOptimizerLateEPCallback(
+ [](FunctionPassManager &FPM, OptimizationLevel Level) {
+ RealtimeSanitizerOptions Opts;
+ FPM.addPass(RealtimeSanitizerPass(Opts));
+ });
+
// Don't add sanitizers if we are here from ThinLTO PostLink. That already
// done on PreLink stage.
if (!IsThinLTOPostLink) {
diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp
b/clang/lib/CodeGen/CodeGenFunction.cpp
index 2b2e23f1e5d7fb..fc388f6f879a1e 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -845,6 +845,12 @@ void CodeGenFunction::StartFunction(GlobalDecl GD,
QualType RetTy,
if (SanOpts.has(SanitizerKind::ShadowCallStack))
Fn->addFnAttr(llvm::Attribute::ShadowCallStack);
+ if (SanOpts.has(SanitizerKind::Realtime)) {
+ for (const FunctionEffectWithCondition &Fe : FD->getFunctionEffects())
+ if (Fe.Effect.kind() == FunctionEffect::Kind::NonBlocking)
+ Fn->addFnAttr(llvm::Attribute::SanitizeRealtime);
+ }
+
// Apply fuzzing attribute to the function.
if (SanOpts.hasOneOf(SanitizerKind::Fuzzer | SanitizerKind::FuzzerNoLink))
Fn->addFnAttr(llvm::Attribute::OptForFuzzing);
diff --git a/clang/lib/Driver/SanitizerArgs.cpp
b/clang/lib/Driver/SanitizerArgs.cpp
index 1fd870b72286e5..7b38f20fc8d059 100644
--- a/clang/lib/Driver/SanitizerArgs.cpp
+++ b/clang/lib/Driver/SanitizerArgs.cpp
@@ -552,11 +552,15 @@ SanitizerArgs::SanitizerArgs(const ToolChain &TC,
SanitizerKind::Leak | SanitizerKind::Thread |
SanitizerKind::Memory | SanitizerKind::KernelAddress |
SanitizerKind::Scudo | SanitizerKind::SafeStack),
- std::make_pair(SanitizerKind::MemTag,
- SanitizerKind::Address | SanitizerKind::KernelAddress |
- SanitizerKind::HWAddress |
- SanitizerKind::KernelHWAddress),
- std::make_pair(SanitizerKind::KCFI, SanitizerKind::Function)};
+ std::make_pair(SanitizerKind::MemTag, SanitizerKind::Address |
+ SanitizerKind::KernelAddress |
+ SanitizerKind::HWAddress |
+
SanitizerKind::KernelHWAddress),
+ std::make_pair(SanitizerKind::KCFI, SanitizerKind::Function),
+ std::make_pair(SanitizerKind::Realtime,
+ SanitizerKind::Address | SanitizerKind::Thread |
+ SanitizerKind::Undefined | SanitizerKind::Memory)};
+
// Enable toolchain specific default sanitizers if not explicitly disabled.
SanitizerMask Default = TC.getDefaultSanitizers() & ~AllRemove;
diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 6e9744607d9ebc..61ec730aa4a5b5 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1431,6 +1431,8 @@ collectSanitizerRuntimes(const ToolChain &TC, const
ArgList &Args,
if (!Args.hasArg(options::OPT_shared))
HelperStaticRuntimes.push_back("hwasan-preinit");
}
+ if (SanArgs.needsRtsanRt() && SanArgs.linkRuntimes())
+ SharedRuntimes.push_back("rtsan");
}
// The stats_client library is also statically linked into DSOs.
@@ -1456,6 +1458,10 @@ collectSanitizerRuntimes(const ToolChain &TC, const
ArgList &Args,
StaticRuntimes.push_back("asan_cxx");
}
+ if (!SanArgs.needsSharedRt() && SanArgs.needsRtsanRt() &&
+ SanArgs.linkRuntimes())
+ StaticRuntimes.push_back("rtsan");
+
if (!SanArgs.needsSharedRt() && SanArgs.needsMemProfRt()) {
StaticRuntimes.push_back("memprof");
if (SanArgs.linkCXXRuntimes())
diff --git a/clang/lib/Driver/ToolChains/Darwin.cpp
b/clang/lib/Driver/ToolChains/Darwin.cpp
index ee6890d5b98f0e..9dfb803e12bbee 100644
--- a/clang/lib/Driver/ToolChains/Darwin.cpp
+++ b/clang/lib/Driver/ToolChains/Darwin.cpp
@@ -1519,6 +1519,8 @@ void DarwinClang::AddLinkRuntimeLibArgs(const ArgList
&Args,
const char *sanitizer = nullptr;
if (Sanitize.needsUbsanRt()) {
sanitizer = "UndefinedBehaviorSanitizer";
+ } else if (Sanitize.needsRtsanRt()) {
+ sanitizer = "RealtimeSanitizer";
} else if (Sanitize.needsAsanRt()) {
sanitizer = "AddressSanitizer";
} else if (Sanitize.needsTsanRt()) {
@@ -1541,6 +1543,11 @@ void DarwinClang::AddLinkRuntimeLibArgs(const ArgList
&Args,
AddLinkSanitizerLibArgs(Args, CmdArgs, "asan");
}
}
+ if (Sanitize.needsRtsanRt()) {
+ assert(Sanitize.needsSharedRt() &&
+ "Static sanitizer runtimes not supported");
+ AddLinkSanitizerLibArgs(Args, CmdArgs, "rtsan");
+ }
if (Sanitize.needsLsanRt())
AddLinkSanitizerLibArgs(Args, CmdArgs, "lsan");
if (Sanitize.needsUbsanRt()) {
@@ -3531,6 +3538,7 @@ SanitizerMask Darwin::getSupportedSanitizers() const {
Res |= SanitizerKind::Address;
Res |= SanitizerKind::PointerCompare;
Res |= SanitizerKind::PointerSubtract;
+ Res |= SanitizerKind::Realtime;
Res |= SanitizerKind::Leak;
Res |= SanitizerKind::Fuzzer;
Res |= SanitizerKind::FuzzerNoLink;
diff --git a/clang/lib/Driver/ToolChains/Linux.cpp
b/clang/lib/Driver/ToolChains/Linux.cpp
index 2265138edbffbe..96680b3412a2db 100644
--- a/clang/lib/Driver/ToolChains/Linux.cpp
+++ b/clang/lib/Driver/ToolChains/Linux.cpp
@@ -800,6 +800,7 @@ SanitizerMask Linux::getSupportedSanitizers() const {
Res |= SanitizerKind::Address;
Res |= SanitizerKind::PointerCompare;
Res |= SanitizerKind::PointerSubtract;
+ Res |= SanitizerKind::Realtime;
Res |= SanitizerKind::Fuzzer;
Res |= SanitizerKind::FuzzerNoLink;
Res |= SanitizerKind::KernelAddress;
diff --git a/clang/test/CodeGen/rtsan_attribute_inserted.c
b/clang/test/CodeGen/rtsan_attribute_inserted.c
new file mode 100644
index 00000000000000..ecba06703fee2c
--- /dev/null
+++ b/clang/test/CodeGen/rtsan_attribute_inserted.c
@@ -0,0 +1,7 @@
+// RUN: %clang -target x86_64-unknown-linux -fsanitize=realtime %s -S
-emit-llvm -o - | FileCheck %s
+
+float process(float *a) [[clang::nonblocking]] { return *a; }
+
+// CHECK-LABEL: @process{{.*}}#0 {
+// CHECK: attributes #0 = {
+// CHECK-SAME: {{.*sanitize_realtime.*}}
diff --git a/clang/test/CodeGen/rtsan_insert_at_entry.c
b/clang/test/CodeGen/rtsan_insert_at_entry.c
new file mode 100644
index 00000000000000..22d568425cbe74
--- /dev/null
+++ b/clang/test/CodeGen/rtsan_insert_at_entry.c
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 -triple aarch64-none-linux-gnu -fsanitize=realtime
-emit-llvm -o - %s | FileCheck %s
+
+// The first instruction after the function is entred should be a call to
+// enable the realtime sanitizer stack
+
+int foo(int *a) [[clang::nonblocking]] { return *a; }
+// CHECK-LABEL: define{{.*}}@foo
+// CHECK-NEXT: entry:
+// CHECK-NEXT: call{{.*}}__rtsan_realtime_enter
diff --git a/clang/test/CodeGen/rtsan_insert_at_exit.c
b/clang/test/CodeGen/rtsan_insert_at_exit.c
new file mode 100644
index 00000000000000..32b381f163f595
--- /dev/null
+++ b/clang/test/CodeGen/rtsan_insert_at_exit.c
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 -triple aarch64-none-linux-gnu -fsanitize=realtime
-emit-llvm -o - %s | FileCheck %s
+
+// __rtsan_realtime_exit should be inserted at all function returns
+
+int bar(int* x) [[clang::nonblocking]] {
+ return *x;
+}
+// CHECK-LABEL: call{{.*}}__rtsan_realtime_exit
+// CHECK-NEXT: ret
diff --git a/clang/test/CodeGen/rtsan_no_attribute_sanitizer_disabled.c
b/clang/test/CodeGen/rtsan_no_attribute_sanitizer_disabled.c
new file mode 100644
index 00000000000000..85742d8b63d9ec
--- /dev/null
+++ b/clang/test/CodeGen/rtsan_no_attribute_sanitizer_disabled.c
@@ -0,0 +1,8 @@
+// RUN: %clang -target x86_64-unknown-linux %s -S -emit-llvm -o - |
FileCheck %s
+
+
+float process(float *a) [[clang::nonblocking]] { return *a; }
+
+// Without the -fsanitize=realtime flag, we shouldn't attach
+// the attribute
+// CHECK-NOT: {{.*sanitize_realtime.*}}
diff --git a/clang/test/Driver/fsanitize.c b/clang/test/Driver/fsanitize.c
index 678fa432fb0a0a..f86c978f221cd4 100644
--- a/clang/test/Driver/fsanitize.c
+++ b/clang/test/Driver/fsanitize.c
@@ -1040,3 +1040,49 @@
// RUN: not %clang --target=aarch64-none-elf -fsanitize=dataflow %s -### 2>&1
| FileCheck %s -check-prefix=UNSUPPORTED-BAREMETAL
// RUN: not %clang --target=arm-arm-none-eabi -fsanitize=shadow-call-stack %s
-### 2>&1 | FileCheck %s -check-prefix=UNSUPPORTED-BAREMETAL
// UNSUPPORTED-BAREMETAL: unsupported option '-fsanitize={{.*}}' for target
+
+// RUN: %clang --target=x86_64-apple-darwin -fsanitize=realtime %s -### 2>&1 |
FileCheck %s --check-prefix=CHECK-RTSAN-X86-64-DARWIN
+// CHECK-RTSAN-X86-64-DARWIN-NOT: unsupported option
+
+// RUN: %clang --target=x86_64-apple-darwin -fsanitize=realtime %s -### 2>&1 |
FileCheck %s --check-prefix=CHECK-RTSAN-X86-64-DARWIN
+// CHECK-RTSAN-X86-64-DARWIN-NOT: unsupported option
+// RUN: %clang --target=x86_64-apple-macos -fsanitize=realtime %s -### 2>&1 |
FileCheck %s --check-prefix=CHECK-RTSAN-X86-64-MACOS
+// CHECK-RTSAN-X86-64-MACOS-NOT: unsupported option
+// RUN: %clang --target=arm64-apple-macos -fsanitize=realtime %s -### 2>&1 |
FileCheck %s --check-prefix=CHECK-RTSAN-ARM64-MACOS
+// CHECK-RTSAN-ARM64-MACOS-NOT: unsupported option
+
+// RUN: %clang --target=arm64-apple-ios-simulator -fsanitize=realtime %s -###
2>&1 | FileCheck %s --check-prefix=CHECK-RTSAN-ARM64-IOSSIMULATOR
+// CHECK-RTSAN-ARM64-IOSSIMULATOR-NOT: unsupported option
+
+// RUN: %clang --target=arm64-apple-watchos-simulator -fsanitize=realtime %s
-### 2>&1 | FileCheck %s --check-prefix=CHECK-RTSAN-ARM64-WATCHOSSIMULATOR
+// CHECK-RTSAN-ARM64-WATCHOSSIMULATOR-NOT: unsupported option
+
+// RUN: %clang --target=arm64-apple-tvos-simulator -fsanitize=realtime %s -###
2>&1 | FileCheck %s --check-prefix=CHECK-RTSAN-ARM64-TVOSSIMULATOR
+// CHECK-RTSAN-ARM64-TVOSSIMULATOR-NOT: unsupported option
+
+// RUN: %clang --target=x86_64-apple-ios-simulator -fsanitize=realtime %s -###
2>&1 | FileCheck %s --check-prefix=CHECK-RTSAN-X86-64-IOSSIMULATOR
+// CHECK-RTSAN-X86-64-IOSSIMULATOR-NOT: unsupported option
+
+// RUN: %clang --target=x86_64-apple-watchos-simulator -fsanitize=realtime %s
-### 2>&1 | FileCheck %s --check-prefix=CHECK-RTSAN-X86-64-WATCHOSSIMULATOR
+// CHECK-RTSAN-X86-64-WATCHOSSIMULATOR-NOT: unsupported option
+
+// RUN: %clang --target=x86_64-apple-tvos-simulator -fsanitize=realtime %s
-### 2>&1 | FileCheck %s --check-prefix=CHECK-RTSAN-X86-64-TVOSSIMULATOR
+// CHECK-RTSAN-X86-64-TVOSSIMULATOR-NOT: unsupported option
+
+// RUN: %clang --target=x86_64-linux-gnu -fsanitize=realtime %s -### 2>&1 |
FileCheck %s --check-prefix=CHECK-RTSAN-X86-64-LINUX
+// CHECK-RTSAN-X86-64-LINUX-NOT: unsupported option
+
+// RUN: not %clang --target=i386-pc-openbsd -fsanitize=realtime %s -### 2>&1 |
FileCheck %s --check-prefix=CHECK-RTSAN-OPENBSD
+// CHECK-RTSAN-OPENBSD: unsupported option '-fsanitize=realtime' for target
'i386-pc-openbsd'
+
+// RUN: not %clang --target=x86_64-linux-gnu -fsanitize=realtime,thread %s
-### 2>&1 | FileCheck %s --check-prefix=CHECK-REALTIME-TSAN
+// CHECK-REALTIME-TSAN: error: invalid argument '-fsanitize=realtime' not
allowed with '-fsanitize=thread'
+
+// RUN: not %clang --target=x86_64-linux-gnu -fsanitize=realtime,address %s
-### 2>&1 | FileCheck %s --check-prefix=CHECK-REALTIME-ASAN
+// CHECK-REALTIME-ASAN: error: invalid argument '-fsanitize=realtime' not
allowed with '-fsanitize=address'
+
+// RUN: not %clang --target=x86_64-linux-gnu -fsanitize=realtime,memory %s
-### 2>&1 | FileCheck %s --check-prefix=CHECK-REALTIME-MSAN
+// CHECK-REALTIME-MSAN: error: invalid argument '-fsanitize=realtime' not
allowed with '-fsanitize=memory'
+
+// RUN: not %clang --target=x86_64-linux-gnu -fsanitize=realtime,undefined %s
-### 2>&1 | FileCheck %s --check-prefix=CHECK-REALTIME-UBSAN
+// CHECK-REALTIME-UBSAN: error: invalid argument '-fsanitize=realtime' not
allowed with '-fsanitize=undefined'
diff --git a/clang/test/Driver/rtsan.c b/clang/test/Driver/rtsan.c
new file mode 100644
index 00000000000000..999e88d066427c
--- /dev/null
+++ b/clang/test/Driver/rtsan.c
@@ -0,0 +1,14 @@
+// RUN: %clang -target x86_64-unknown-linux -fsanitize=realtime %s -S
-emit-llvm -o - | FileCheck %s
+// RUN: %clang -O1 -target x86_64-unknown-linux -fsanitize=realtime %s -S
-emit-llvm -o - | FileCheck %s
+// RUN: %clang -O2 -target x86_64-unknown-linux -fsanitize=realtime %s -S
-emit-llvm -o - | FileCheck %s
+// RUN: %clang -O3 -target x86_64-unknown-linux -fsanitize=realtime %s -S
-emit-llvm -o - | FileCheck %s
+// RUN: %clang -target x86_64-unknown-linux -fsanitize=realtime %s -S
-emit-llvm -flto=thin -o - | FileCheck %s
+// RUN: %clang -O2 -target x86_64-unknown-linux -fsanitize=realtime %s -S
-emit-llvm -flto=thin -o - | FileCheck %s
+// RUN: %clang -target x86_64-unknown-linux -fsanitize=realtime %s -S
-emit-llvm -flto -o - | FileCheck %s
+// RUN: %clang -O2 -target x86_64-unknown-linux -fsanitize=realtime %s -S
-emit-llvm -flto -o - | FileCheck %s
+
+// Ensure the rtsan_realtime calls are never optimized away
+
+int foo(int *a) [[clang::nonblocking]] { return *a; }
+// CHECK: __rtsan_realtime_enter
+// CHECK: __rtsan_realtime_exit
>From 57de56187f721fa257ba84923e9f24bd910074b5 Mon Sep 17 00:00:00 2001
From: Chris Apple <cja-priv...@pm.me>
Date: Fri, 9 Aug 2024 08:42:22 -0700
Subject: [PATCH 2/3] [PR] Test hasAnyFunctionEffects before iterating
---
clang/lib/CodeGen/CodeGenFunction.cpp | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp
b/clang/lib/CodeGen/CodeGenFunction.cpp
index fc388f6f879a1e..364333e780b6d7 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -846,9 +846,12 @@ void CodeGenFunction::StartFunction(GlobalDecl GD,
QualType RetTy,
Fn->addFnAttr(llvm::Attribute::ShadowCallStack);
if (SanOpts.has(SanitizerKind::Realtime)) {
- for (const FunctionEffectWithCondition &Fe : FD->getFunctionEffects())
- if (Fe.Effect.kind() == FunctionEffect::Kind::NonBlocking)
- Fn->addFnAttr(llvm::Attribute::SanitizeRealtime);
+ if (FD && FD->getASTContext().hasAnyFunctionEffects()) {
+ for (const FunctionEffectWithCondition &Fe : FD->getFunctionEffects()) {
+ if (Fe.Effect.kind() == FunctionEffect::Kind::NonBlocking)
+ Fn->addFnAttr(llvm::Attribute::SanitizeRealtime);
+ }
+ }
}
// Apply fuzzing attribute to the function.
>From e047ca614dad3719cd7828d0b688a2186eaff679 Mon Sep 17 00:00:00 2001
From: Chris Apple <cja-priv...@pm.me>
Date: Sat, 10 Aug 2024 08:41:31 -0700
Subject: [PATCH 3/3] Documentation draft 1
---
clang/docs/RealtimeSanitizer.rst | 81 ++++++++++++++++++++++++++++++++
clang/docs/ReleaseNotes.rst | 5 ++
2 files changed, 86 insertions(+)
create mode 100644 clang/docs/RealtimeSanitizer.rst
diff --git a/clang/docs/RealtimeSanitizer.rst b/clang/docs/RealtimeSanitizer.rst
new file mode 100644
index 00000000000000..f9af41467df05f
--- /dev/null
+++ b/clang/docs/RealtimeSanitizer.rst
@@ -0,0 +1,81 @@
+=================
+RealtimeSanitizer
+=================
+
+.. contents::
+ :local:
+
+Introduction
+============
+RealtimeSanitizer (a.k.a. RTSan) is a real-time safety testing tool for C and
+C++ projects. RTSan can be used to detect real-time violations,such as calls to
+methods that are not safe for use in functions with deterministic runtime
+requirements.
+
+The tool can detect the following types of real-time violations:
+
+* System calls
+* Allocations
+* Exceptions
+
+These checks are put in place when compiling with the
+``-fsanitize=realtime`` flag, for functions marked with
+``[[clang::nonblocking]]``.
+
+.. code-block:: c
+ void process_audio(float* buffer) [[clang::nonblocking]] {
+ ...
+ }
+
+The runtime slowdown introduced by RealtimeSanitizer is trivial. Code in
+real-time contexts without real-time safety violations have no slowdown.
+
+How to build
+============
+
+Build LLVM/Clang with `CMake <https://llvm.org/docs/CMake.html>` and enable the
+``compiler-rt`` runtime. An example CMake configuration that will allow for the
+use/testing of RealtimeSanitizer:
+
+.. code-block:: console
+
+ $ cmake -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_PROJECTS="clang"
-DLLVM_ENABLE_RUNTIMES="compiler-rt" <path to source>/llvm
+
+Usage
+=====
+
+There are two requirements:
+1. The code must be compiled with the ``-fsanitize=realtime`` flag.
+2. Functions that are subject to real-time constraints must be
+ marked with the ``[[clang::nonblocking]]`` attribute.
+
+Typically, these attributes should be added onto the functions that are entry
+points for threads with real-time priority. These threads are subject to a
fixed
+callback time, such as audio callback threads or rendering loops in video game
+code.
+
+.. code-block:: console
+ % cat example_realtime_violation.cpp
+ int main() [[clang::nonblocking]] {
+ int* p = new int;
+ return 0;
+ }
+
+ # Compile and link
+ % clang -fsanitize=realtime -g example_realtime_violation.cpp
+
+If a real-time safety violation is detected in a ``[[clang::nonblocking]]``
+context, or any function invoked by that function, the program will exit with a
+non-zero exit code.
+
+.. code-block:: console
+ % clang -fsanitize=realtime -g example_realtime_violation.cpp
+ % ./a.out
+ Real-time violation: intercepted call to real-time unsafe function `malloc`
in real-time context! Stack trace:
+ #0 0x00010065ad9c in __rtsan::PrintStackTrace() rtsan_stack.cpp:45
+ #1 0x00010065abcc in __rtsan::Context::ExpectNotRealtime(char const*)
rtsan_context.cpp:78
+ #2 0x00010065b8d0 in malloc rtsan_interceptors.cpp:289
+ #3 0x000195bd7bd0 in operator new(unsigned long)+0x1c
(libc++abi.dylib:arm64+0x16bd0)
+ #4 0xb338001000dbf68 (<unknown module>)
+ #5 0x0001958960dc (<unknown module>)
+ #6 0x45737ffffffffffc (<unknown module>)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 6796a619ba97f8..79f721169fdbb2 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -349,6 +349,11 @@ Moved checkers
Sanitizers
----------
+- Introduced Realtime Sanitizer, activated by using the -fsanitize=realtime
+ flag. This sanitizer detects unsafe system library calls, such as memory
+ allocations and mutex locks. If any such function is called during invocation
+ of a function marked with the ``[[clang::nonblocking]]`` attribute, an error
+ is printed to the console and the process exits non-zero.
Python Binding Changes
----------------------
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