Nick Sarnie 031d99836d [SPIRV] Error in backend for vararg functions (#169111)
SPIR-V doesn't support variadic functions, though we make an exception
for `printf`.

If we don't error, we generate invalid SPIR-V because the backend has no
idea how to codegen vararg functions as it is not described in the spec.
We get asm like this:

```
%27 = OpFunction %6 None %7
%28 = OpFunctionParameter %4
                                        ; -- End function
```

The above asm is totally invalid, there's no `OpFunctionEnd` and it
causes crashes in downstream tools like `spirv-as` and `spirv-link`.

We already have many `printf` tests locking down that this doesn't break
`printf`, it was already handled elsewhere at the time the error check
runs.

Note the SPIR-V Translator does the same thing, see
[here](https://github.com/KhronosGroup/SPIRV-LLVM-Translator/pull/2703).

---------

Signed-off-by: Nick Sarnie <nick.sarnie@intel.com>
2025-11-25 15:17:04 +00:00

The LLVM Compiler Infrastructure

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Welcome to the LLVM project!

This repository contains the source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and run-time environments.

The LLVM project has multiple components. The core of the project is itself called "LLVM". This contains all of the tools, libraries, and header files needed to process intermediate representations and convert them into object files. Tools include an assembler, disassembler, bitcode analyzer, and bitcode optimizer.

C-like languages use the Clang frontend. This component compiles C, C++, Objective-C, and Objective-C++ code into LLVM bitcode -- and from there into object files, using LLVM.

Other components include: the libc++ C++ standard library, the LLD linker, and more.

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Consult the Getting Started with LLVM page for information on building and running LLVM.

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