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df3630c194
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>
49 lines
1.2 KiB
Plaintext
49 lines
1.2 KiB
Plaintext
#include <metal_stdlib>
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using namespace metal;
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uint2 tint_first_trailing_bit(uint2 v) {
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uint2 x = uint2(v);
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uint2 const b16 = select(uint2(16u), uint2(0u), bool2((x & uint2(65535u))));
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x = (x >> b16);
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uint2 const b8 = select(uint2(8u), uint2(0u), bool2((x & uint2(255u))));
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x = (x >> b8);
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uint2 const b4 = select(uint2(4u), uint2(0u), bool2((x & uint2(15u))));
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x = (x >> b4);
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uint2 const b2 = select(uint2(2u), uint2(0u), bool2((x & uint2(3u))));
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x = (x >> b2);
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uint2 const b1 = select(uint2(1u), uint2(0u), bool2((x & uint2(1u))));
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uint2 const is_zero = select(uint2(0u), uint2(4294967295u), (x == uint2(0u)));
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return uint2((((((b16 | b8) | b4) | b2) | b1) | is_zero));
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}
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void firstTrailingBit_45eb10() {
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uint2 res = tint_first_trailing_bit(uint2());
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}
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struct tint_symbol {
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float4 value [[position]];
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};
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float4 vertex_main_inner() {
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firstTrailingBit_45eb10();
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return float4();
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}
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vertex tint_symbol vertex_main() {
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float4 const inner_result = vertex_main_inner();
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tint_symbol wrapper_result = {};
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wrapper_result.value = inner_result;
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return wrapper_result;
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}
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fragment void fragment_main() {
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firstTrailingBit_45eb10();
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return;
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}
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kernel void compute_main() {
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firstTrailingBit_45eb10();
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return;
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}
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