diff options
| author | Jason Ekstrand <[email protected]> | 2017-09-06 18:33:38 -0700 |
|---|---|---|
| committer | Jason Ekstrand <[email protected]> | 2017-10-25 16:14:09 -0700 |
| commit | fa6e74e33e5bc5f6fba8f9de76b8b059515e708f (patch) | |
| tree | 93b60d1c7fbddacfab4d13ac3735cb3b43c00e2c /src/intel/compiler/brw_fs.cpp | |
| parent | a6d38f476beaaf0a9677cfc168172121b5779570 (diff) | |
intel/fs: Handle flag read/write aliasing in needs_src_copy
In order to implement the ballot intrinsic, we do a MOV from flag
register to some GRF. If that GRF is used in a SEL, cmod propagation
helpfully changes it into a MOV from the flag register with a cmod.
This is perfectly valid but when lower_simd_width comes along, it simply
splits into two instructions which both have conditional modifiers.
This is a problem since we're reading the flag register. This commit
makes us check whether or not flags_written() overlaps with the flag
values that we are reading via the instruction source and, if we have
any interference, will force us to emit a copy of the source.
Reviewed-by: Matt Turner <[email protected]>
Cc: [email protected]
Diffstat (limited to 'src/intel/compiler/brw_fs.cpp')
| -rw-r--r-- | src/intel/compiler/brw_fs.cpp | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/src/intel/compiler/brw_fs.cpp b/src/intel/compiler/brw_fs.cpp index 30e8841242d..4616529abcf 100644 --- a/src/intel/compiler/brw_fs.cpp +++ b/src/intel/compiler/brw_fs.cpp @@ -5013,7 +5013,9 @@ needs_src_copy(const fs_builder &lbld, const fs_inst *inst, unsigned i) { return !(is_periodic(inst->src[i], lbld.dispatch_width()) || (inst->components_read(i) == 1 && - lbld.dispatch_width() <= inst->exec_size)); + lbld.dispatch_width() <= inst->exec_size)) || + (inst->flags_written() & + flag_mask(inst->src[i], type_sz(inst->src[i].type))); } /** |