jcs.org
qemu with hax to log dma reads & writes
jcs.org/2018/11/12/vfio
qemu/host-utils.h: Reduce the operation count in the fallback ctpop
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
+11
-14
+11
-14
include/qemu/host-utils.h
+11
-14
include/qemu/host-utils.h
···
327
327
#else
328
328
val = (val & 0x55) + ((val >> 1) & 0x55);
329
329
val = (val & 0x33) + ((val >> 2) & 0x33);
330
-
val = (val & 0x0f) + ((val >> 4) & 0x0f);
330
+
val = (val + (val >> 4)) & 0x0f;
331
331
332
332
return val;
333
333
#endif
···
344
344
#else
345
345
val = (val & 0x5555) + ((val >> 1) & 0x5555);
346
346
val = (val & 0x3333) + ((val >> 2) & 0x3333);
347
-
val = (val & 0x0f0f) + ((val >> 4) & 0x0f0f);
348
-
val = (val & 0x00ff) + ((val >> 8) & 0x00ff);
347
+
val = (val + (val >> 4)) & 0x0f0f;
348
+
val = (val + (val >> 8)) & 0x00ff;
349
349
350
350
return val;
351
351
#endif
···
360
360
#if QEMU_GNUC_PREREQ(3, 4)
361
361
return __builtin_popcount(val);
362
362
#else
363
-
val = (val & 0x55555555) + ((val >> 1) & 0x55555555);
364
-
val = (val & 0x33333333) + ((val >> 2) & 0x33333333);
365
-
val = (val & 0x0f0f0f0f) + ((val >> 4) & 0x0f0f0f0f);
366
-
val = (val & 0x00ff00ff) + ((val >> 8) & 0x00ff00ff);
367
-
val = (val & 0x0000ffff) + ((val >> 16) & 0x0000ffff);
363
+
val = (val & 0x55555555) + ((val >> 1) & 0x55555555);
364
+
val = (val & 0x33333333) + ((val >> 2) & 0x33333333);
365
+
val = (val + (val >> 4)) & 0x0f0f0f0f;
366
+
val = (val * 0x01010101) >> 24;
368
367
369
368
return val;
370
369
#endif
···
379
378
#if QEMU_GNUC_PREREQ(3, 4)
380
379
return __builtin_popcountll(val);
381
380
#else
382
-
val = (val & 0x5555555555555555ULL) + ((val >> 1) & 0x5555555555555555ULL);
383
-
val = (val & 0x3333333333333333ULL) + ((val >> 2) & 0x3333333333333333ULL);
384
-
val = (val & 0x0f0f0f0f0f0f0f0fULL) + ((val >> 4) & 0x0f0f0f0f0f0f0f0fULL);
385
-
val = (val & 0x00ff00ff00ff00ffULL) + ((val >> 8) & 0x00ff00ff00ff00ffULL);
386
-
val = (val & 0x0000ffff0000ffffULL) + ((val >> 16) & 0x0000ffff0000ffffULL);
387
-
val = (val & 0x00000000ffffffffULL) + ((val >> 32) & 0x00000000ffffffffULL);
381
+
val = (val & 0x5555555555555555ULL) + ((val >> 1) & 0x5555555555555555ULL);
382
+
val = (val & 0x3333333333333333ULL) + ((val >> 2) & 0x3333333333333333ULL);
383
+
val = (val + (val >> 4)) & 0x0f0f0f0f0f0f0f0fULL;
384
+
val = (val * 0x0101010101010101ULL) >> 56;
388
385
389
386
return val;
390
387
#endif