[SPIR-V] Use of Nonsemantic.DebugBreak creates invalid SPIR-V

[jkoenen]

Description
I'm trying to use the NonSemantic.DebugBreak instruction (specified here: https://github.khronos.org/SPIRV-Registry/nonsemantic/NonSemantic.DebugBreak.html) using DXC. Unfortunately DXC fails with an error.

Steps to Reproduce
Simple Shader reproducing the issue: https://godbolt.org/z/6dW8eK79a
--->

Actual Behavior
dxc outputs the following error:

fatal error: failed to optimize SPIR-V: Id 1 is defined more than once
note: please file a bug report on https://github.com/Microsoft/DirectXShaderCompiler/issues with source code if possible

Compiler returned: 5

Environment

• DXC version libdxcompiler.so: 1.9(dev;1-9efbb6c3); libdxil.so: 1.9
• Host Operating System Windows 11

[Keenuts]

Hi, thanks for the report! Looks like this was an overlook in the inline SPIR-V implementation: when the function was void as return, we refused to emit a result type (which works for instructions like OpStore), but not for instructions in an extended instruction set.
PR sent!