diff options
Diffstat (limited to 'src/mesa/drivers/dri/i965/brw_context.c')
| -rw-r--r-- | src/mesa/drivers/dri/i965/brw_context.c | 27 |
1 files changed, 26 insertions, 1 deletions
diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c index 12f898abdb5..216b788a7ee 100644 --- a/src/mesa/drivers/dri/i965/brw_context.c +++ b/src/mesa/drivers/dri/i965/brw_context.c @@ -483,7 +483,32 @@ brw_initialize_context_constants(struct brw_context *brw) ctx->Const.QuadsFollowProvokingVertexConvention = false; ctx->Const.NativeIntegers = true; - ctx->Const.UniformBooleanTrue = 1; + + /* 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 match what the + * CMP instruction returns. + * + * The Sandybridge BSpec's description of the CMP instruction matches that + * of the Ivybridge PRM. (The description in the Sandybridge PRM is seems + * to have not been updated from Ironlake). Its CMP instruction behaves like + * Ivybridge and newer. + */ + if (brw->gen >= 6) + ctx->Const.UniformBooleanTrue = ~0; + else + ctx->Const.UniformBooleanTrue = 1; /* From the gen4 PRM, volume 4 page 127: * |