microsoft / microsoft/DirectXShaderCompiler

Passing `int4` constants to `dst` causes ICE

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bug needs-triage
Dominant language
C++
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Description

Description
Passing dst 2 int4 arguments causes a stack overflow.

Steps to Reproduce
Shader:

[shader("pixel")]
void PSMain() {
    int4 r = dst(int4(1, 2, 3, 4), int4(5, 6, 7, 8));
    if (r.x != 1) discard;
}

Command: dxc.exe -T ps_6_6 -E PSMain dst_int4.hlsl

Actual Behavior

Internal compiler error: stack overflow

Environment

  • dxcompiler.dll: 1.9(5184-21d28f72)(1.9.2602.17) - 1.9.2602.17 (21d28f727)
  • Windows 10

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by running the provided dxc.exe command with the HLSL shader and PSMain entry point to reproduce the stack overflow. Trace how dst handles two int4 constant arguments, then add a regression test showing compilation completes without an internal compiler error.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
compilers
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Quiet
Clarity
Clearly specified
Newbie friendliness
68/100

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