Created attachment 43418 [details]
piglit OpenGL GLSL case, this case fail on pineview and pass on ironlake

System Environment:
--------------------------
Libdrm:         (master)2.4.23-6-g550fe2ca3b29ad2191eab4fdfbed9ed21e25492d
Mesa:           (master)6ed0f2ac112d22278cf051c2cee9c2199a9025ea
Xserver:                (master)xorg-server-1.9.99.901-197-gea1ffd3e60bdcedbec5a6f28929f8677bf45d450
Xf86_video_intel:               (master)2.14.0-25-g9184af921bc2f332fcb6c9b47001414378eab8e2


Bug detailed description:
-------------------------
This bug hapens on Pineview. 
This issue happens to both OpenGL GLSL and OpenGL ES 2.0 GLSL

According to OpenGL ES specificaton, section 3.8.2:
"The built-in variable gl_FragCoord holds the window coordinates x, y, z, and 1/w for the fragment. The z component of gl_FragCoord undergoes an implied conversion to floating-point. This conversion must leave the values 0 and 1 invariant. Note that this z component already has a polygon offset added in, if enabled (see section 3.5.2. The 1/w value is computed from the wc coordinate (see section 2.12)."

Following OpenGL GLSL case could be used to reproduce the issue:
[require]
GLSL >= 1.10

[vertex shader]
void main()
{
        gl_Position = gl_Vertex;
        gl_Position.w = 2.0;
}

[fragment shader]
void main()
{
        gl_FragColor = vec4(1.0, gl_FragCoord.w, 1.0, 0.0);
}

[test]
draw rect -1 -1 2 2
relative probe rgb (0.5, 0.5) (1.0, 0.5, 1.0)