<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/97898>97898</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            An error occurred in the backend when compiling CUDA code with clang18
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          yanan-sjh
      </td>
    </tr>
</table>

<pre>
    I encountered an error while compiling **CUDA** code using **clang++-18**. The error message is as follows:
```
fatal error: error in backend: Cannot select: 0x55722baf9d20: i64,ch = stacksave 0x55722baf9cb0
In function: _Z5entrydPdS_PimP4int2i
clang++-18: error: clang frontend command failed with exit code 70 (use -v to see invocation)
Ubuntu clang version 18.1.0 (++20240220094926+390dcd4cbbf5-1~exp1~20240220214944.50)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
clang++-18: note: diagnostic msg: 
********************

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang++-18: note: diagnostic msg: /tmp/host-b24319.cu
clang++-18: note: diagnostic msg: /tmp/host-sm_75-8d8351.cu
clang++-18: note: diagnostic msg: /tmp/host-b24319.sh
clang++-18: note: diagnostic msg: 
```
The kernel code is as follows. The following code can be successfully compiled using **nvcc**.
```cpp
#define MAX_THREAD_PER_BLOCK 899
#define MIN_BLOCK_PER_MULTIPROCESSOR 8
static const int SIZE = 2448;
static const int FN = 5;

__host__ void host_callee(ulonglong* param_15, ulonglong* param_17) { }
__device__ __forceinline__ void func_53(const int deep) {
        if ((deep) > (1)) {
        }
        const uint len1 = 1U;
        uchar* p1 = (uchar*)alloca(sizeof(uchar) * (len1));
}

__global__ __launch_bounds__(MAX_THREAD_PER_BLOCK, MIN_BLOCK_PER_MULTIPROCESSOR) void entry(const double input, double* result, double* oval, int* fence, ulong fptr, int2* ldst, const int deep) {
        func_53((1));
}
```
The CUDA version is 12.1.The program consists of two parts: `kernel.cu` and `host.cu`and it is compiled using the following command:
```
clang++-18 -v -x cuda -I/usr/local/cuda-12.1/lib64 -I/usr/local/cuda-12.1/targets/x86_64-linux/include/ --cuda-path=/usr/local/cuda-12.1/ -c host.cu --cuda-gpu-arch=sm_75
```

All files are attached. 


[Uploading fatal_error.zip…]()

</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJysVk1v2zwS_jX0ZSBDoj4sHXywY_utsXkbI3Gwi14EiqQstjQpiJST9NDfviAl20madrHbBRJZmhkO5_OZIcaIg-J8jtIlSlcT0ttGd_MXoogKzNdmUmn2Mt8CV1T3yvKOMyAKeNfpDp4aITlQfWyFFOoACC8QXtw8rhbDG1DNOPTmyqOSqAPCS4SXQZQPtCnsGz5qPHJjyIGDMEAM1FpK_WRQvEDhCoULlIXjn_-siSVyOIjixahBKKgI_cYVc7QbopS2YLjk1DpC-JymM4wrUhcMh44isgThG9oAildgLKHfDDnx14K0Gi_cKqh7Ra3Qyp0sv6Rc2e6F7dhDuRPHXSKUxWKQfefp2T734llQd1pZrpiL35EoBjURkjN4ErYB_izsEL1ZCAjnveEQnMBqMJyDUCdNiTcDF8N1j1WvbD-qPvHOCK0gyqfR1J8fDMEhTkKMw7BICpwhvIyLkFGW0Kqq0yD6wZ_b6MdZCEdJkSTTNLzcsSfdgfsoPudZmSVBSwMpVP8cHFQ_ijQdJwyOmnHpBFttxPM5eMYSKTlbCR8FhDe96RDeVEL9KmRKW-5-mSAHpY0VFI7m4E8PBYH_4G_Q4J-72_XiYQ2L_X5x8wn2n9awubu9vfvn9vNfsNnerh9gf-fJy8e_4H69u7vfX4py1_G205QbwxkY3XeUI5wbhAtwWSXGaCqI5Qy6XoGhnWjtRaDjIF0qXVfZi8r_KhB4Y48twptGGxtUOImjYkr7P1VkjuUsDXKWx2n0f1A32mWa_znTb1vfIcY33ikuhy55gxcDoAwfDnq8BCUKKg6mpy5VdS_ly4hcnL2BKHWidASmd1fTtj2XXcx4LRSHvxf_Kvef7teLVblb35fL27ubf0BeFD_JbT8PTC_29-Ptfru7v7tZPzzc3UM-SBtLnNtUK2NBKAsP2y9rj0o4SXIUL38htvnshdKLxPAsSxf5soSTFgz8O3X956qzl1od3L8D6ZZ05FhGKcI38BFj5ioVzZaAZquzasZPgvKyhLKsdUe5UFIofr7MgWSZxgjnVysZ5-2o6GxlIeoBm_ILM147SuQg553s5XIUFoPW3qmVXEXe_ejxlf9FTxvSeR8GrvN5JCFcEOmazjWh-M51fWUWrgacsFM7GHHVejVgiMFB6opIHwNJekWbstK9YqYsEc4_KgwX4N8Vgrvfx89PlUv0mO4r6UC_7a1TMXw7QztuevmOpk9EOopQ1n3WXDk8GjMLdWu7kYsdWzLjz_8-T9d8XpPzQVx-blG3ClymkTAQ4Wk0dYy204eOHP29wlgDugb7pF3JWeO7PguH_nbgk4UeSlEWujIeKI4grFP6rovtu973w_VXK8RbIHIjNngG2jMCwfYyoFyxSIQ3jh44FxxNVFnyn4SsH5gG4c04MP20RHgjFJU94whvIAj8iZbYBsWr36qDgMIYgPOxQ9sHpKPuqEfsD50cngspoRaSGz91iLWENpxN4bXM-EyXj63UhLkA-iWr9LvL9Lto0RqjPESLDKUrXw8j1E3YPGZFXJAJn0czHOJZnMXhpJlnHBdhEedRNctqljCeJhmp8iqbFWk0q-KJmPuNYxZmUZzMonAaRVmaZSTieRTnYVSgJORHIuRUytNxqrvDRBjT83kxy4t8IknFpfHrK8aKP4FnIozdNtvN3Zmg6g8GJaF0lXbVYoWVfL44L7Oa0r5z661QvobGLRKeGq5e7bi-pP1E8YuaL6Aon_SdnDfWtn5ZxRuENwdhm76aUn106ZSn80_Qdvqr20bxxpvqymNw5TTH_w4AAP__Cl9yfw">