[SPIR-V] DXC crash - make [[vk::ext_literal]] be able to take const static as a well as a literal.

[AlexSabourinDev]

Description
Hello,

DXC crashes when compiling a shader that uses inline SPIRV to expose OpGroupNonUniformBallotBitCount.

Specifically, the use of a static const uint for the Group Operation.

Steps to Reproduce

This simple shader will reproduce the issue:

static uint const ReduceOperation = 0;

[[vk::ext_instruction(/* OpGroupNonUniformBallotBitCount */ 342)]]
uint OpGroupNonUniformBallotBitCount(uint scope, [[vk::ext_literal]] uint groupOperation, uint4 ballot);

[numthreads(1, 1, 1)]
void CS()
{
	OpGroupNonUniformBallotBitCount(vk::SubgroupScope, ReduceOperation, 0);
}

Issue does not occur when using either an enum or a macro for the ReduceOperation constant.

Godbolt link: https://godbolt.org/z/vcWzGeEG9

Command line: -T cs_6_6 -E CS -spirv -fspv-target-env=vulkan1.3

Actual Behavior

Using the DXC C++ API, I get this crash with no output log from DXC:

Exception thrown at 0x00007FFC468C6552 (dxcompiler.dll) in Samples.exe: 0xC0000005: Access violation writing location 0x0000000000000070.

Compiler explorer simply outputs:

Program terminated with signal: SIGSEGV

Environment

• DXC versions:
  • libdxcompiler.so: 1.8(dev;1-af955d60)
  • dxcompiler.dll: 1.7 - 1.7.2308.7 (69e54e2); dxil.dll: 1.7(101.7.2308.12)
• Host Operating System: Windows 10

[devshgraphicsprogramming]

This is because its supposed to be a static const not const, thats the only use that gets interpreted as a compile time constant like C++ constexpr.

Btw you can actually include C++ SPIR-V Headers in your HLSL if you want the nice enums like I do
https://github.com/Devsh-Graphics-Programming/Nabla/blob/master/include/nbl/builtin/hlsl/spirv_intrinsics/subgroup_ballot.hlsl

[AlexSabourinDev]

Unfortunately - the error exists as well with static const

And neat! That's really convenient - I didn't know those existed

[devshgraphicsprogramming]

Ok your best bet are the non-C++11 headers (just C++ so its not enum class)
https://godbolt.org/z/W1P5MoeYh

I think the name for this issue should be "Make [vk::ext_literal] be able to take const static as a well as a literal"

P.S. If you removed the ext_literal it would be trying to plumb in the result-ID of the constant declaration

[AlexSabourinDev]

That makes sense to me - I'll happily change the name for clarity!

[AlexSabourinDev]

I think another reasonable conclusion is also a clearer error message. Currently a segfault isnt ideal

I've also edited the original issue to highlight that this also occurs with static const. I wasn't clear enough in the original description.

[sudonatalie]

Thanks for reporting @AlexSabourinDev, working on a quick fix.