On Mon, Nov 20, 2017 at 2:50 PM, Ian Romanick <[email protected]> wrote: > On 11/20/2017 02:33 PM, Matt Turner wrote: >> MADs don't take immediate sources, but we allow them in the IR since it >> simplifies a lot of things. I neglected to consider that case. >> >> Fixes: 4009a9ead490 ("i965/fs: Allow saturate propagation to propagate >> negations into MADs.") >> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103616 >> Reported-and-Tested-by: Ruslan Kabatsayev <[email protected]> >> --- >> src/intel/compiler/brw_fs_saturate_propagation.cpp | 10 ++++++++-- >> 1 file changed, 8 insertions(+), 2 deletions(-) >> >> diff --git a/src/intel/compiler/brw_fs_saturate_propagation.cpp >> b/src/intel/compiler/brw_fs_saturate_propagation.cpp >> index 1c97a507d8..d6cfa79a61 100644 >> --- a/src/intel/compiler/brw_fs_saturate_propagation.cpp >> +++ b/src/intel/compiler/brw_fs_saturate_propagation.cpp >> @@ -88,8 +88,14 @@ opt_saturate_propagation_local(fs_visitor *v, bblock_t >> *block) >> scan_inst->src[0].negate = >> !scan_inst->src[0].negate; >> inst->src[0].negate = false; >> } else if (scan_inst->opcode == BRW_OPCODE_MAD) { >> - scan_inst->src[0].negate = >> !scan_inst->src[0].negate; >> - scan_inst->src[1].negate = >> !scan_inst->src[1].negate; >> + for (int i = 0; i < 2; i++) { >> + if (scan_inst->src[i].file == IMM) { >> + brw_negate_immediate(scan_inst->src[i].type, >> + >> &scan_inst->src[i].as_brw_reg()); >> + } else { >> + scan_inst->src[i].negate = >> !scan_inst->src[i].negate; >> + } >> + } > > Is this going to affect the number of generated instructions if there > are multiple MADs using the same immediate value for a multiply source? > Would it be better to find a multiply source that isn't an immediate?
Interesting question. I think the answer is no, since brw_fs_combine_constants.cpp builds its list of constants by ignoring their signs. Since source negation is free, it just loads positive values into registers and negates them with a source modifier if needed. I ran shader-db to confirm -- no changes on SKL. _______________________________________________ mesa-dev mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/mesa-dev
