From 07e6648e1230721b9d2c8ed298719a12de9e1d33 Mon Sep 17 00:00:00 2001
From: Michael Klimenko <mklimenko29@gmail.com>
Date: Wed, 2 Aug 2023 21:50:35 +0200
Subject: [PATCH] Enable Intel oneAPI DPC++/C++ compiler build (#16587)

Last week I fixed error #16484 found when trying to build onnxruntime
with the icpx compiler. Another thing I found out is that icpx uses
-ffast-math flag by default. You can check it by running the compiler
with -v flag like following:

```bash
# Setup the environment
. /opt/intel/oneapi/setvars.sh
# Compile any file to see all the implicit flags
icpx -v main.cpp
```

This leads to a bunch of warnings during the build like:

```bash
In file included from /mnt/f/wsl_home/onnxruntime/onnxruntime/test/providers/cpu/tensor/upsample_op_test.cc:5:
In file included from /mnt/f/wsl_home/onnxruntime/onnxruntime/test/providers/provider_test_utils.h:6:
In file included from /mnt/f/wsl_home/onnxruntime/onnxruntime/test/providers/checkers.h:10:
In file included from /mnt/f/wsl_home/onnxruntime/onnxruntime/core/util/math_cpuonly.h:68:
In file included from /mnt/f/wsl_home/onnxruntime/build/Linux/RelWithDebInfo/_deps/eigen-src/Eigen/Core:172:
/mnt/f/wsl_home/onnxruntime/build/Linux/RelWithDebInfo/_deps/eigen-src/Eigen/src/Core/MathFunctions.h:1019:12: warning: comparison with NaN always evaluates to false in fast floating point modes [-Wtautological-constant-compare]
    return isnan EIGEN_NOT_A_MACRO (x);
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~
```

And some tests are failing as well, usually with infinities involved. To
list a few:

```bash
# ...
1: [  FAILED  ] IsInfTest.test_isinf_float
1: [  FAILED  ] IsInfTest.test_isinf_double
1: [  FAILED  ] IsInfTest.test_isinf_positive_float
1: [  FAILED  ] IsInfTest.test_isinf_positive_double
1: [  FAILED  ] IsInfTest.test_isinf_negative_float
1: [  FAILED  ] IsInfTest.test_isinf_negative_double
1: [  FAILED  ] IsNaNOpTest.IsNaNFloat
1: [  FAILED  ] IsNaNOpTest.IsNaNDouble
# ...
```

This PR adds a quick global check for the IntelLLVM compiler, as in the
way its name is reported by CMake and then, depending on the compiler
driver, sets either MSVC-like or GCC-like switch to disable fast-maths.

Probably a bit cleaner solution would be to use
```target_compile_options(${TARGET} PRIVATE MEOW)``` instead of a
global-wide ```set(CMAKE_CXX_FLAGS MEOW)```, but then we'd be required
to add it to all the individual targets and execution providers and this
will lead to a lot of code duplication.
---
 cmake/CMakeLists.txt | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/cmake/CMakeLists.txt b/cmake/CMakeLists.txt
index 104b8ac213..db5f817fdb 100644
--- a/cmake/CMakeLists.txt
+++ b/cmake/CMakeLists.txt
@@ -30,6 +30,17 @@ endif()
 # Project
 project(onnxruntime C CXX ASM)
 
+# Disable fast-math for Intel oneAPI compiler
+if("${CMAKE_CXX_COMPILER_ID}" MATCHES "IntelLLVM")
+  if("${CMAKE_CXX_COMPILER_ID}" MATCHES "MSVC-like")
+    # Using icx-cl compiler driver with MSVC-like arguments
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /fp:precise")
+  else()
+    # Using icpx compiler driver
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-fast-math")
+  endif()
+endif()
+
 # Needed for Java
 set(CMAKE_C_STANDARD 99)