Currently, when resources are declared without explicit register bindings, DXC assigns them after GlobalDCE runs. This can lead to inconsistent register assignments across entry points (depending on optimizations), which causes mismatched resource IDs.

A common case is bindless-style includes, e.g. declaring multiple textures without explicit bindings but with spaces. In this situation, the generated binaries may not match across different entry points or when compiling as a library.

Solution

This PR introduces a new flag:

-consistent-bindings

When enabled, DXC will generate stable bindings by letting GlobalDCE eliminate only unused resources' symbols. Then, the bindings are generated and finally the unused resources are stripped again.

This ensures consistent register assignments across all entry points, whether compiling as individual shaders or as a library.

• Resources are preserved until final binding assignment.
• After assignment, unused bindings are stripped to avoid breaking optimization assumptions.
• The behavior is similar to -flegacy-resource-reservation, but tailored for ensuring binding consistency.

Example

Command:

dxc -consistent-bindings -E main -T cs_6_0 myFile.hlsl

Shader:

Texture2D a;
Texture2D b;
RWTexture2D<float4> c;

[numthreads(1,1,1)]
void main() {
   c[0.xx] = b[0.xx];
}

[numthreads(1,1,1)]
void main2() {
   c[0.xx] = a[0.xx];
}

Generated bindings:

• a → t0
• b → t1
• c → u0

Both main and main2 will consistently use the same bindings (b at t1, c at u0), regardless of entry point or library compilation.

Notes

• Step 1 of 2 toward fixing Allow unused registers to be output to reflection #5105.
• Replaces custom preprocessing logic with compiler-side handling for stability and maintainability.