more SETcc improvements to backend #4904
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WalterBright
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| cg = cat(cg,getregs(retregs)); | ||
| cg = genregs(cg,0x19,reg,reg); // SBB reg,reg | ||
| cg = gen2(cg,0xF7,modregrmx(3,3,reg)); // NEG reg | ||
| } |
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The latency of SBB+NEG is 3 vs. 2 for SETcc+MOVZX, so you might want to use SETcc here as well though it requires 4 bytes for the code.
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That's only beneficent for loops.
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While I wait impatiently for ddmd (hint, hint) I decided to do some tuneups to the back end. If you notice any code sequences where clang/gcc do a better job than dmd, let me know. |
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MartinNowak
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Aug 18, 2015
more SETcc improvements to backend
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Make better use of SETcc instructions.