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Currently polyfilled for all backends. HLSL should be able to map this to 'firstbitlow', but there might need to be some special case handling for 0 (undocumented behavior). For now just polyfill. CTS tests: https://github.com/gpuweb/cts/pull/1003 Bug: tint:1367 Bug: tint:1449 Change-Id: I8125b32687196678906e5a9d056b4f2efd885073 Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/81502 Kokoro: Kokoro <noreply+kokoro@google.com> Reviewed-by: David Neto <dneto@google.com> Commit-Queue: Ben Clayton <bclayton@google.com>
46 lines
1.3 KiB
HLSL
46 lines
1.3 KiB
HLSL
uint4 tint_first_trailing_bit(uint4 v) {
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uint4 x = uint4(v);
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const uint4 b16 = (bool4((x & uint4((65535u).xxxx))) ? uint4((0u).xxxx) : uint4((16u).xxxx));
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x = (x >> b16);
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const uint4 b8 = (bool4((x & uint4((255u).xxxx))) ? uint4((0u).xxxx) : uint4((8u).xxxx));
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x = (x >> b8);
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const uint4 b4 = (bool4((x & uint4((15u).xxxx))) ? uint4((0u).xxxx) : uint4((4u).xxxx));
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x = (x >> b4);
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const uint4 b2 = (bool4((x & uint4((3u).xxxx))) ? uint4((0u).xxxx) : uint4((2u).xxxx));
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x = (x >> b2);
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const uint4 b1 = (bool4((x & uint4((1u).xxxx))) ? uint4((0u).xxxx) : uint4((1u).xxxx));
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const uint4 is_zero = ((x == uint4((0u).xxxx)) ? uint4((4294967295u).xxxx) : uint4((0u).xxxx));
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return uint4((((((b16 | b8) | b4) | b2) | b1) | is_zero));
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}
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void firstTrailingBit_110f2c() {
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uint4 res = tint_first_trailing_bit(uint4(0u, 0u, 0u, 0u));
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}
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struct tint_symbol {
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float4 value : SV_Position;
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};
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float4 vertex_main_inner() {
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firstTrailingBit_110f2c();
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return float4(0.0f, 0.0f, 0.0f, 0.0f);
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}
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tint_symbol vertex_main() {
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const float4 inner_result = vertex_main_inner();
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tint_symbol wrapper_result = (tint_symbol)0;
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wrapper_result.value = inner_result;
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return wrapper_result;
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}
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void fragment_main() {
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firstTrailingBit_110f2c();
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return;
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}
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[numthreads(1, 1, 1)]
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void compute_main() {
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firstTrailingBit_110f2c();
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return;
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}
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