OpenCL regression due to missing spirv function

[Felix Weinmann]

I have OpenCL code that works with version 1.0.15468.25-2build1, but breaks with version 1.0.15468.25-2ubuntu0.1 of libigc1 and libigdfcl1 (on Ubuntu 24.04.2) due to:

error: undefined reference to _Z37__spirv_ImageSampleExplicitLod_Ruint4PU3AS140__spirv_SampledImage__void_1_0_0_0_0_0_0Dv2_iif'
in function: '__spirv_ImageSampleExplicitLod_Ruint4(__spirv_SampledImage__void_1_0_0_0_0_0_0 AS1*, int vector[2], int, float)' called by kernel: 'rgb2nv12'

error: backend compiler failed build.

Downgrading the package version of libigc1 and libigdfcl1 to the prior version fixes the compilation failure. I've appended a small code example with the first kernel that fails to compile with the new version.

[Felix Weinmann (lixfel)]

(Build command in the minimal reproducable example is slightly wrong, -lOpenCL needs to be at the end of the command)

[Chintan (cmpatel)]

While this regression aligns with the IGC update, it’s worth exploring whether the issue stems from the switch to the distro-provided Khronos SPIR-V translator.

Since the _Z37__spirv_ImageSampleExplicitLod_Ruint4 symbol relates to SPIR-V image sampling logic, there’s a possibility that:

The Khronos translator behaves differently than IGC’s previous internal translator.
A mismatch between IGC and the external translator version may be responsible.

To confirm, could we:

Test the .spv file directly with ocloc to isolate whether the translator is the source of failure?
Verify the Khronos translator version used in both IGC builds?
Attempt building IGC without the -DIGC_OPTION__USE_KHRONOS_SPIRV_TRANSLATOR_IN_SC=1 flag to determine if the issue is tied to the translator switch rather than core IGC behavior?

[Timo Aaltonen (tjaalton)]

the only change in the update was to switch the translator:

intel-graphics-compiler (1.0.15468.25-2ubuntu0.1) noble; urgency=medium

  * Enable IGC_OPTION__USE_KHRONOS_SPIRV_TRANSLATOR_IN_SC in build
    (LP: #2085370)

so it's clearly at issue here ;)