Compiler Sanitizers

Intel® oneAPI DPC++/C++ Compiler

Developer Guide and Reference

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ID 767253

Date 3/31/2025

Version

Public

Compiler Sanitizers

Compiler sanitizers give you tools to detect bugs and/or errors, including buffer overflows, accesses, dangling pointers, uses-of-uninitialized memory and other types of undefined behavior. The compiler sanitizers work with OpenMP* and SYCL*.

System Requirements

Platform Support: CPU device and PVC GPU is supported on Linux.
GPU Configuration: This feature supports one PVC GPU card. For the Intel® oneAPI Level Zero (Level Zero) runtime, use the ZE_AFFINITY_MASK=0 environment variable to set this configuration.

Device-Side AddressSanitizer

The device-side AddressSanitizer (ASan) supports the error checks in the following table for SYCL and OpenMP device code.

Feature	OpenMP	SYCL
bad-context	n/a	Supported
bad-free	n/a	Supported
double-free	n/a	Supported
invalid argument	Supported	Supported
kernel filter	Not supported	Supported
memory leak	Supported	Supported
memory overhead statistics	Supported	Supported
misaligned access	Supported	Supported
multiple error reports	Supported	Supported
nullpointer access	Supported	Supported
out-of-bounds on device global	Supported	Supported
out-of-bounds on global unified shared memory (USM)	Supported	Supported
out-of-bounds on local	Supported	Supported
out-of-bounds on memory buffer	n/a	Supported
out-of-bounds on private	Supported	Supported
use-after-free	Supported	Supported

OpenMP

Compile your OpenMP application and execute it with ASan enabled (only supported on GPU), for example:

icpx -fiopenmp -fopenmp-targets=spir64 -Xarch_device -fsanitize=address -g -O2 -o demo demo.cpp

Run on GPU with:

export LIBOMPTARGET_PLUGIN=unified_runtime     
export UR_ENABLE_LAYERS=UR_LAYER_ASAN
 ./demo

NOTE:

Setting the ONEAPI_DEVICE_SELECTOR=level_zero:gpu environment variable for OpenMP offload on GPU device will cause errors.

SYCL

Compile a SYCL example with ASan enabled:

icpx -fsycl -Xarch_device -fsanitize=address -g -O2 -o demo demo.cpp

Run on CPU with:

export ONEAPI_DEVICE_SELECTOR=opencl:cpu
./demo

Run on GPU with:

export ONEAPI_DEVICE_SELECTOR=level_zero:gpu
./demo

Runtime Flags

Runtime flags can be passed to the device-side ASan with the UR_LAYER_ASAN_OPTIONS environment variable, shown in the following example:

export UR_LAYER_ASAN_OPTIONS="quarantine_size_mb:1" ./demo
export UR_LAYER_ASAN_OPTIONS=redzone:32 ./demo 
export UR_LAYER_ASAN_OPTIONS=max_redzone:1024 ./demo export 
UR_LAYER_ASAN_OPTIONS="redzone:32;max_redzone:1024" ./demo

Flag	Default Value	Description
`detect_locals`	true	Enable runtime support for detecting out-of-bounds errors on local memory and shared local memory (SLM).
`detect_privates`	true	Enable runtime support for detecting out-of-bounds errors on private memory.
`halt_on_error`	true	Crash the program after printing the first error report. The flag is only effective if your code was compiled with the `-fsanitize-recover=address` compile option.
`max_redzone`	2048	Maximal size (in bytes) of redzones around USM heap objects.
`quarantine_size_mb`	0	The size (in MB) of quarantine used to detect `use-after-free` errors. Lower values may reduce memory usage, but increase the chance of false negatives. The default value is 0, indicating that while the sanitizer continues to detect `use-after-free` errors, it does not employ quarantine to minimize false negatives, thereby reducing memory overhead.
`redzone`	16	Minimal size (in bytes) of redzones around USM heap objects. Requirement: redzone >= 16, is a power of two.

Device-Side MemorySanitizer

Device-side MemorySanitizer (MSan), a tool in LLVM used to detect uninitialized memory (UUM) in C/C++ code, supports OpenMP and SYCL device code starting with the Intel® oneAPI DPC++/C++ Compiler 2025.1 release. To activate this feature for device code, use the -Xarch_device -fsanitize=memory options when compiling your source code. This SYCL accelerator extension provides a device-side MemorySanitizer, focusing on device USM to address common use cases.

OpenMP

Compiling and running OpenMP code with MSan enabled:

Compile your OpenMP example with device-side MemorySanitizer enabled:

icpx -fiopenmp -fopenmp-targets=spir64 -Xarch_device -fsanitize=memory -g -o demo demo.cpp

Run your example on GPU:

export LIBOMPTARGET_PLUGIN=unified_runtime     
export UR_ENABLE_LAYERS=UR_LAYER_MSAN
export ZE_AFFINITY_MASK=0
./demo

NOTE:

Setting the ONEAPI_DEVICE_SELECTOR=level_zero:gpu environment variable for OpenMP offload on GPU device will cause errors.

SYCL

Compiling and running OpenMP code with MSan enabled:

Compile your SYCL example with device-side MemorySanitizer enabled:
```
icpx -fsycl -Xarch_device -fsanitize=memory -g -o demo demo.cpp
```

Run your example on GPU:

export ZE_AFFINITY_MASK=0
export ONEAPI_DEVICE_SELECTOR=level_zero:gpu 
./demo

Run your example on CPU:

export ONEAPI_DEVICE_SELECTOR=opencl:cpu 
./demo

Limitations

The compiler sanitizers have the following limitations:

Kernel execution is sequential. Concurrent execution is forced to into sequential execution when device-side ASan is enabled.
Device-side ASan may lead to an increase of the usage of private memory, causing a reduction in the maximum workgroup size a kernel can support. In this case, you may encounter a UR_RESULT_ERROR_INVALID_WORK_GROUP_SIZE error message. To fix this, you need to reduce the SYCL local workgroup size or OpenMP overlay management protocol (OMP) teams.
A large number of workgroups on a GPU may lead to the device-side ASan skipping an out-of-bound check for private/local memory.
OpenMP (C/C++) only supports execution on a GPU device.

Parent topic: Optimization and Programming

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