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i965/fs: Implement the WaCMPInstFlagDepClearedEarly work-around.

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Prevents piglit regressions from the next patch.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This commit is contained in:
Matt Turner 2015-02-03 17:38:49 -08:00
parent 661c8bb220
commit 7e60794392
1 changed files with 36 additions and 1 deletions
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37
src/mesa/drivers/dri/i965/brw_fs_generator.cpp
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@ -1734,7 +1734,42 @@ fs_generator::generate_code(const cfg_t *cfg, int dispatch_width)
brw_F16TO32(p, dst, src[0]);
break;
case BRW_OPCODE_CMP:
brw_CMP(p, dst, inst->conditional_mod, src[0], src[1]);
/* The Ivybridge/BayTrail WaCMPInstFlagDepClearedEarly workaround says
* that when the destination is a GRF that the dependency-clear bit on
* the flag register is cleared early.
*
* Suggested workarounds are to disable coissuing CMP instructions
* or to split CMP(16) instructions into two CMP(8) instructions.
*
* We choose to split into CMP(8) instructions since disabling
* coissuing would affect CMP instructions not otherwise affected by
* the errata.
*/
if (dispatch_width == 16 && brw->gen == 7 && !brw->is_haswell) {
if (dst.file == BRW_GENERAL_REGISTER_FILE) {
brw_set_default_compression_control(p, BRW_COMPRESSION_NONE);
brw_CMP(p, firsthalf(dst), inst->conditional_mod,
firsthalf(src[0]), firsthalf(src[1]));
brw_set_default_compression_control(p, BRW_COMPRESSION_2NDHALF);
brw_CMP(p, sechalf(dst), inst->conditional_mod,
sechalf(src[0]), sechalf(src[1]));
brw_set_default_compression_control(p, BRW_COMPRESSION_COMPRESSED);
multiple_instructions_emitted = true;
} else if (dst.file == BRW_ARCHITECTURE_REGISTER_FILE) {
/* For unknown reasons, the aforementioned workaround is not
* sufficient. Overriding the type when the destination is the
* null register is necessary but not sufficient by itself.
*/
assert(dst.nr == BRW_ARF_NULL);
dst.type = BRW_REGISTER_TYPE_D;
brw_CMP(p, dst, inst->conditional_mod, src[0], src[1]);
} else {
unreachable("not reached");
}
} else {
brw_CMP(p, dst, inst->conditional_mod, src[0], src[1]);
}
break;
case BRW_OPCODE_SEL:
brw_SEL(p, dst, src[0], src[1]);