It's about DX9, hlsl 3, and Intel integrated graphics.
In certain situations, PS reads incorrect values from input attributes (or VS outputs wrong values). I.e. with VS code
def c0, 1, 1, 1, 1 ... dcl_blendindices7 o7 ... mov o7, c0
and PS code:
dcl_blendindices7 v7 mov oC0, v7
v7 in PS has invalid data. In my particular case, using other attribute index fixes issue (f.e. dcl_blendindices6).
I've personally reproduced it on Windows 7-x64 with Core i7-3770, HD 4000 with latest drivers (10.18.10.4653), but we have encountered it on various other Intel integrated graphics & cpu & OS combinations.
I can privately provide GPA frame capture containing this issue, or other information if needed.