Possible ESSL Compiler Bug on Mali-T880

Hello,

I am seeing an issue where a shader will erroneously result in a solid black color.  If a line is changed to use a multiply add (adding the smallest possible float value), the correct color is displayed.  Any insight into what is triggering the problem and possible workarounds would be greatly appreciated.

#version 310 es

precision highp float;

layout(std140) uniform;

layout(shared, binding = 8) uniform EgGrConstantBufferShaderType_PerMaterial {

    vec4 m_PerMaterialPacked0;

};

layout(shared, binding = 9) uniform EgGrConstantBufferShaderType_PerInstance {

    mat4 m_PerInstancePacked0;

    mat4 m_PerInstancePacked1;

    vec4 m_PerInstancePacked2;

    vec4 m_PerInstancePacked3;

    vec4 m_PerInstancePacked4;

};

layout(binding = 0) uniform sampler2D m_oUniqueSamplerT_0;

layout(binding = 1) uniform sampler2D m_oUniqueSamplerT_1;

layout(location = 0)  in highp vec4 VtxGeoOutput0;

layout(location = 2)  in highp vec4 VtxGeoOutput2;

layout(location = 0) out highp vec4 PixOutput0;

float g_fNearlyZero = 1.17549435e-38F;

#define MUL(a, b) (a * b)// + g_fNearlyZero)                                    ///< Changing this to (a * b + g_fNearlyZero) results in a correct color being displayed

void main()

{

    vec3  value0 = texture(m_oUniqueSamplerT_1, VtxGeoOutput2.xy).xyz;          // Diffuse / albedo texture color

    float value1 = texture(m_oUniqueSamplerT_0, VtxGeoOutput2.xy).x;            // 'Occlusion' scalar

    vec3  value2 = value0 * m_PerMaterialPacked0.x;                             // m_PerMaterialPacked0.x = 1.0 (scalar to control brightness of the diffuse)

    vec3  value3 = MUL(value1, value2);                                         ///< Use MUL macro to show issue. Scale diffuse by occlusion value

    vec3  value4 = m_PerInstancePacked3.xyz + m_PerInstancePacked2.xyz;         // m_PerInstancePacked3.xyz = vec3(1.0, 1.0, 1.0) + m_PerInstancePacked2.xyz = vec3(0.0, 0.0, 0.0)

    vec3  value5 = value3 * value4;                                             //

    PixOutput0.xyz = max(value5, 0.0);

    PixOutput0.w = 1.0;

    return;

}

Target hardware:

Mali-T880 GLES 3.1 v1.r9p0 in a Samsung Galaxy S7 Edge International version.

GL_RENDERER: Mali-T880

GL_VERSION: OpenGL ES 3.1 v1.r9p0-12dev0.c37094c9ad948aa7a7b056e38dcda762

GL_SHADING_LANGUAGE_VERSION: OpenGL ES GLSL ES 3.10

I've tested this code on a Galaxy Note 5 (Mali-T760) without problems.

Thanks,

Jeremiah