[SPIR-V] DXC crashed with asuint()

[shobomaru]

Description LLVM assertion failed.

Steps to Reproduce dxc -T cs_6_0 -spirv path/to/file.hlsl

HLSL code:

RWSturcturedBuffer<uint> Out;
[numthreads(1, 1, 1)]
void main()
{
	Out[0] = asuint(-1);
}

If we change the code as follows, the issue is not occurred.

Out[0] = asuint(-1 * 1);

Actual Behavior

Assertion failed: (SI.isSigned() == E->getType()->isSignedIntegerOrEnumerationType() && "Invalid evaluation result."), function Success, file ExprConstant.cpp, line 6199.

Environment

• DXC version: libdxcompiler.dylib: 1.8(dev;4640-45018c75)
• Host Operating System: Windows 11 23H2 and macOS 14.5

[gorrila007]

RWStructuredBuffer Out; [numthreads(1, 1, 1)] void main() { Out[0] = asuint(-1); // Ensure correct handling of -1 }

[Keenuts]

Thanks for the issue! I bet this is similar to https://github.com/microsoft/DirectXShaderCompiler/issues/6712 We probably forward the layout for no reason.

[Keenuts]

Mmm not quite. For some reasons we lack an implicit cast in the AST, and thus we send a signed int to a function taking only an unsigned int. And we fail on an assert during the constant evaluation:

ExprConstant.cpp

assert(SI.isSigned() == E->getType()->isSignedIntegerOrEnumerationType() && "Invalid evaluation result.");

CallExpr 0x555555a75140 'unsigned int'
|-ImplicitCastExpr 0x555555a75128 'unsigned int (*)(int)' <FunctionToPointerDecay>
| `-DeclRefExpr 0x555555a750c0 'unsigned int (int)' lvalue Function 0x555555a74f20 'asuint' 'unsigned int (int)'
`-ImplicitCastExpr 0x555555a75170 'int' <IntegralCast>
  `-UnaryOperator 0x555555a74eb8 'literal int' prefix '-'
    `-IntegerLiteral 0x555555a74e98 'literal int' 1

And this issue also affects the DXIL side, as we fail in the frontend. Removing the SPIR-V tag.

[damyanp]

As this only manifests as an assert, moving this to dormant. PR's fixing this would be gladly accepted!