Documents arithmetic reduction semantics#391
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gnzlbg wants to merge 1 commit intorust-lang:masterfrom
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Looks good! I think CI is failing though? |
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@alexcrichton they are failing on release mode only because my implementation of these in rustc had a bug. I've fixed it here: rust-lang/rust#49231 I'll close this until that lands, and reopen it again once the tests pass. |
kennytm
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fix vector fmin/fmax non-fast/fast intrinsics NaN handling This bugs shows up in release mode tests of `stdsimd`: rust-lang/stdarch#391 . The intrinsics are thoroughly tested there for roundoff errors, NaN, and overflow behavior. The problem was that the non-fast intrinsics where specifying `NoNaNs == true`, which meant that they don't support NaNs. This is incorrect, the non-fast intrinsics should handle NaNs properly. Also, the "fast" intrinsics where specifying `NoNaNs == false` which meant that they support NaNs and then fast-math, which probably disables this support. This was not intended either. I've added a comment specifying what the boolean flags do.
kennytm
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Mar 22, 2018
fix vector fmin/fmax non-fast/fast intrinsics NaN handling This bugs shows up in release mode tests of `stdsimd`: rust-lang/stdarch#391 . The intrinsics are thoroughly tested there for roundoff errors, NaN, and overflow behavior. The problem was that the non-fast intrinsics where specifying `NoNaNs == true`, which meant that they don't support NaNs. This is incorrect, the non-fast intrinsics should handle NaNs properly. Also, the "fast" intrinsics where specifying `NoNaNs == false` which meant that they support NaNs and then fast-math, which probably disables this support. This was not intended either. I've added a comment specifying what the boolean flags do.
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This PR documents the semantics of the arithmetic reductions
sum,product,min, andmaxfor integers in the presence of integer overflow, and for floating point numbers in the presence of round-off errors andNaNs.It does so by adding test for these semantics for all portable vectors involved.