[CTS] SPIR-V Validation failure, "Expected Image Operand ConstOffset to be a const object"

[jkwak-work]

Three CTS tests are occasionally causing the crash of deqp-vk.exe.

dEQP-VK.glsl.texture_gather.offset.implementation_offset.2d.rgba8.size_pot.clamp_to_edge_repeat
dEQP-VK.glsl.texture_gather.offset.implementation_offset.2d.rgba8.size_pot.mirrored_repeat_clamp_to_edge
dEQP-VK.glsl.texture_gather.offset.implementation_offset.2d.rgba8.size_pot.repeat_mirrored_repeat

When the validation is enabled, those tests fail with the following message,

Expected Image Operand ConstOffset to be a const objec

A simple repro is following,

#extension GL_EXT_gpu_shader5 : require

layout (location = 0) out mediump vec4 o_color;

layout (location = 0) in highp vec2 v_texCoord;

layout (binding = 0) uniform highp sampler2D u_sampler;
layout (binding = 1) uniform offset { highp ivec2 u_offset; };

void main(void)
{
                o_color = textureGatherOffset(u_sampler, v_texCoord, u_offset);
}

When the shader above is stored as test.slang, observe the validation error with the following command,

$ slangc.exe -target spirv -entry main -stage fragment -allow-glsl test.slang

error: line 53: Expected Image Operand ConstOffset to be a const object
  %29 = OpImageGather %v4float %24 %27 %int_0 ConstOffset %21

(0): internal error 99999: Validation of generated SPIR-V failed. SPIRV generated:
; SPIR-V
; Version: 1.5
; Generator: Khronos; 40
; Bound: 37
; Schema: 0
               OpCapability Shader
               OpMemoryModel Logical GLSL450
               OpEntryPoint Fragment %main "main" %11 %offset %u_sampler %31 %entryPointParam_main_o_color %v_texCoord
               OpExecutionMode %main OriginUpperLeft

               ; Debug Information
               OpSource Slang 1
               OpName %v_texCoord "v_texCoord"  ; id %9
               OpName %SLANG_ParameterGroup_offset_std140 "SLANG_ParameterGroup_offset_std140"  ; id %13
               OpMemberName %SLANG_ParameterGroup_offset_std140 0 "u_offset"
               OpName %offset "offset"  ; id %17
               OpName %u_sampler "u_sampler"  ; id %26
               OpName %entryPointParam_main_o_color "entryPointParam_main.o_color"  ; id %34
               OpName %main "main"  ; id %2

               ; Annotations
               OpDecorate %v_texCoord Location 0
               OpDecorate %SLANG_ParameterGroup_offset_std140 Block
               OpMemberDecorate %SLANG_ParameterGroup_offset_std140 0 Offset 0
               OpDecorate %offset Binding 1
               OpDecorate %offset DescriptorSet 0
               OpDecorate %u_sampler Binding 0
               OpDecorate %u_sampler DescriptorSet 0
               OpDecorate %entryPointParam_main_o_color Location 0

               ; Types, variables and constants
       %void = OpTypeVoid
          %3 = OpTypeFunction %void
      %float = OpTypeFloat 32
    %v2float = OpTypeVector %float 2
%_ptr_Input_v2float = OpTypePointer Input %v2float
%_ptr_Private_v2float = OpTypePointer Private %v2float
        %int = OpTypeInt 32 1
      %v2int = OpTypeVector %int 2
%SLANG_ParameterGroup_offset_std140 = OpTypeStruct %v2int
%_ptr_Uniform_SLANG_ParameterGroup_offset_std140 = OpTypePointer Uniform %SLANG_ParameterGroup_offset_std140
      %int_0 = OpConstant %int 0
%_ptr_Uniform_v2int = OpTypePointer Uniform %v2int
         %22 = OpTypeImage %float 2D 2 0 0 1 Unknown
         %23 = OpTypeSampledImage %22
%_ptr_UniformConstant_23 = OpTypePointer UniformConstant %23
    %v4float = OpTypeVector %float 4
%_ptr_Private_v4float = OpTypePointer Private %v4float
%_ptr_Output_v4float = OpTypePointer Output %v4float
 %v_texCoord = OpVariable %_ptr_Input_v2float Input
         %11 = OpVariable %_ptr_Private_v2float Private
     %offset = OpVariable %_ptr_Uniform_SLANG_ParameterGroup_offset_std140 Uniform
  %u_sampler = OpVariable %_ptr_UniformConstant_23 UniformConstant
         %31 = OpVariable %_ptr_Private_v4float Private
%entryPointParam_main_o_color = OpVariable %_ptr_Output_v4float Output

               ; Function main
       %main = OpFunction %void None %3
          %4 = OpLabel
          %7 = OpLoad %v2float %v_texCoord
               OpStore %11 %7
         %20 = OpAccessChain %_ptr_Uniform_v2int %offset %int_0
         %21 = OpLoad %v2int %20
         %24 = OpLoad %23 %u_sampler
         %27 = OpLoad %v2float %v_texCoord
         %29 = OpImageGather %v4float %24 %27 %int_0 ConstOffset %21
               OpStore %31 %29
               OpStore %entryPointParam_main_o_color %29
               OpReturn
               OpFunctionEnd