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authorIan Romanick <[email protected]>2015-02-03 21:12:28 +0200
committerIan Romanick <[email protected]>2015-03-17 14:59:43 -0700
commitce3f46397d77141156f81dd7fcf06fb936e2b0ef (patch)
tree9ebf8b1426beb34d801275fba3e03eac4b020995 /doxygen
parentd35720da9b9824d104532028775e497491f433ad (diff)
i965/fs: Handle CMP.nz ... 0 and AND.nz ... 1 similarly in cmod propagation
Espically on platforms that do not natively generate 0u and ~0u for Boolean results, we generate a lot of sequences where a CMP is followed by an AND with 1. emit_bool_to_cond_code does this, for example. On ILK, this results in a sequence like: add(8) g3<1>F g8<8,8,1>F -g4<0,1,0>F cmp.l.f0(8) g3<1>D g3<8,8,1>F 0F and.nz.f0(8) null g3<8,8,1>D 1D (+f0) iff(8) Jump: 6 The AND.nz is obviously redundant. By propagating the cmod, we can instead generate add.l.f0(8) null g8<8,8,1>F -g4<0,1,0>F (+f0) iff(8) Jump: 6 Existing code already handles the propagation from the CMP to the ADD. Shader-db results: GM45 (0x2A42): total instructions in shared programs: 3550829 -> 3550788 (-0.00%) instructions in affected programs: 10028 -> 9987 (-0.41%) helped: 24 Iron Lake (0x0046): total instructions in shared programs: 4993146 -> 4993105 (-0.00%) instructions in affected programs: 9675 -> 9634 (-0.42%) helped: 24 Ivy Bridge (0x0166): total instructions in shared programs: 6291870 -> 6291794 (-0.00%) instructions in affected programs: 17914 -> 17838 (-0.42%) helped: 48 Haswell (0x0426): total instructions in shared programs: 5779256 -> 5779180 (-0.00%) instructions in affected programs: 16694 -> 16618 (-0.46%) helped: 48 Broadwell (0x162E): total instructions in shared programs: 6823088 -> 6823014 (-0.00%) instructions in affected programs: 15824 -> 15750 (-0.47%) helped: 46 No chage on Sandy Bridge or on any platform when NIR is used. v2: Add unit tests suggested by Matt. Remove spurious writes_flag() check on scan_inst when scan_inst is known to be BRW_OPCODE_CMP (also suggested by Matt). v3: Fix some comments and remove some explicit int() casts in fs_reg constructors in the unit tests. Both suggested by Matt. Signed-off-by: Ian Romanick <[email protected]> Reviewed-by: Matt Turner <[email protected]>
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