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Cycles: Using OpenCL popcount() in PMJ sampler.

This commit is contained in:
Stefan Werner 2020-03-10 08:53:30 +01:00
parent 7b8ac04d86
commit 811569dc11
1 changed files with 4 additions and 1 deletions
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5
intern/cycles/kernel/kernel_random.h
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@ -294,12 +294,15 @@ ccl_device_inline bool sample_is_even(int pattern, int sample)
if (pattern == SAMPLING_PATTERN_PMJ) {
/* See Section 10.2.1, "Progressive Multi-Jittered Sample Sequences", Christensen et al.
* We can use this to get divide sample sequence into two classes for easier variance
* estimation. There must be a more elegant way of writing this? */
* estimation. */
#if defined(__GNUC__) && !defined(__KERNEL_GPU__)
return __builtin_popcount(sample & 0xaaaaaaaa) & 1;
#elif defined(__NVCC__)
return __popc(sample & 0xaaaaaaaa) & 1;
#elif defined(__KERNEL_OPENCL__)
return popcount(sample & 0xaaaaaaaa) & 1;
#else
/* TODO(Stefan): popcnt intrinsic for Windows with fallback for older CPUs. */
int i = sample & 0xaaaaaaaa;
i = i - ((i >> 1) & 0x55555555);
i = (i & 0x33333333) + ((i >> 2) & 0x33333333);