Bug 33742

These 3 oglconform cases segfault on Sandy Bridge (both desktop and mobile) while passes on Ironlake:
(2.0)vertexshader(advanced.TestLights)
(2.0)vertexshader(advanced.TestMaterials)
(2.0)vertexshader(advanced.TestLightsTwoSided)

./oglconform64 -test vertexshader advanced.TestLights -v 2 -D 33 -s

oglconform64: brw_eu.h:177: brw_reg: Assertion `nr < 128' failed.
Aborted (core dumped)

#0  0x0000003e07e329c5 in raise () from /lib64/libc.so.6
#1  0x0000003e07e341a5 in abort () from /lib64/libc.so.6
#2  0x0000003e07e2b945 in __assert_fail () from /lib64/libc.so.6
#3  0x00007ffff6ca5858 in brw_reg (file=<value optimized out>,
    nr=<value optimized out>, subnr=<value optimized out>,
    type=<value optimized out>, vstride=<value optimized out>,
    width=<value optimized out>, hstride=1, swizzle=228, writemask=15)
    at brw_eu.h:177
#4  0x00007ffff6ca7915 in brw_vec8_reg (c=0x7ffffffcd6f0) at brw_eu.h:229
#5  brw_vec8_grf (c=0x7ffffffcd6f0) at brw_eu.h:472
#6  brw_vs_alloc_regs (c=0x7ffffffcd6f0) at brw_vs_emit.c:370
#7  0x00007ffff6ca9a36 in brw_vs_emit (c=0x7ffffffcd6f0) at brw_vs_emit.c:1898
#8  0x00007ffff6ca5049 in do_vs_prog (brw=0x1a24290, vp=0x1eac840,
    key=0x7fffffff8390) at brw_vs.c:85
#9  0x00007ffff6ca523e in brw_upload_vs_prog (brw=0x1a24290) at brw_vs.c:151
#10 0x00007ffff6ca44b6 in brw_validate_state (brw=0x1a24290)
    at brw_state_upload.c:397
#11 0x00007ffff6c9473a in brw_try_draw_prims (ctx=0x1a24290, arrays=0x1a74c08,
    prim=0x1a73324, nr_prims=1, ib=0x0,
    index_bounds_valid=<value optimized out>, min_index=0, max_index=2)
    at brw_draw.c:362
#12 brw_draw_prims (ctx=0x1a24290, arrays=0x1a74c08, prim=0x1a73324,
    nr_prims=1, ib=0x0, index_bounds_valid=<value optimized out>, min_index=0,
    max_index=2) at brw_draw.c:447
#13 0x00007ffff6d74eee in vbo_exec_vtx_flush (exec=<value optimized out>,
    unmap=<value optimized out>) at vbo/vbo_exec_draw.c:381
#14 0x00007ffff6d720bc in vbo_exec_FlushVertices_internal (
    ctx=<value optimized out>, unmap=<value optimized out>)
    at vbo/vbo_exec_api.c:911
#15 0x00007ffff6d7210a in vbo_exec_FlushVertices (ctx=<value optimized out>,
    flags=1) at vbo/vbo_exec_api.c:945
#16 0x00007ffff6d31c76 in _mesa_ReadPixels (x=50, y=50, width=1, height=1,
    format=6408, type=5126, pixels=0x7fffffff8600) at main/readpix.c:171
#17 0x0000000000701725 in DrawLitAndTestResult(char*, float*, float*, vec4*, vec
4*, vec4*, vec3*, unsigned int, int, int) ()
#18 0x00000000007034e0 in TestLights() ()
#19 0x000000000070393f in ShaderVertexShaderExec(_testParameters*) ()
#20 0x0000000000c2262e in callFunctionHandleExceptionsInner(long (*)(_testParameters*), long (*)(), _testParameters*, char*) ()
#21 0x0000000000c2277a in callFunctionHandleExceptions(long (*)(_testParameters*), long (*)(), _testParameters*) ()
#22 0x0000000000c211a3 in Driver(testR*, testF*) ()
#23 0x0000000000be40ab in Exec(_TK_EventRec*) ()
#24 0x0000000000c2019e in tkExec(long (*)(_TK_EventRec*)) ()
#25 0x0000000000be1308 in tkShellExecute(long, long, long (*)(_TK_EventRec*), testR*) ()
#26 0x0000000000be2807 in main ()

The assertion failure looks similar to bug#30173