+ ctx->Const.VertexID_is_zero_based = true;
+
+ /* Regarding the CMP instruction, the Ivybridge PRM says:
+ *
+ * "For each enabled channel 0b or 1b is assigned to the appropriate flag
+ * bit and 0/all zeros or all ones (e.g, byte 0xFF, word 0xFFFF, DWord
+ * 0xFFFFFFFF) is assigned to dst."
+ *
+ * but PRMs for earlier generations say
+ *
+ * "In dword format, one GRF may store up to 8 results. When the register
+ * is used later as a vector of Booleans, as only LSB at each channel
+ * contains meaning [sic] data, software should make sure all higher bits
+ * are masked out (e.g. by 'and-ing' an [sic] 0x01 constant)."
+ *
+ * We select the representation of a true boolean uniform to be ~0, and fix
+ * the results of Gen <= 5 CMP instruction's with -(result & 1).
+ */
+ ctx->Const.UniformBooleanTrue = ~0;