[libc][docs] Add GPU math conformance test results to support page #156263
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@llvm/pr-subscribers-libc Author: Leandro Lacerda (leandrolcampos) ChangesThis patch enhances the GPU support documentation page ( Patch is 22.44 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/156263.diff 1 Files Affected:
diff --git a/libc/docs/gpu/support.rst b/libc/docs/gpu/support.rst
index 3fb2df8e6f2ca..4243900fb81d4 100644
--- a/libc/docs/gpu/support.rst
+++ b/libc/docs/gpu/support.rst
@@ -281,3 +281,169 @@ Function Name Available RPC Required
assert |check| |check|
__assert_fail |check| |check|
============= ========= ============
+
+math.h
+------
+
+The following table presents the conformance test results for higher math functions on the GPU. The results show the maximum observed ULP (Units in the Last Place) distance when comparing the GPU implementation against a correctly rounded reference computed on the host CPU. In addition to the C standard math library (LLVM-libm), these tests are conducted against CUDA Math and HIP Math, for comparison only.
+
++------------------------+-------------+---------------+-----------------------------------------------------------------------------------+
+| Function | Test Method | ULP Tolerance | Max ULP Distance |
+| | | +--------------------+--------------------+--------------------+--------------------+
+| | | | llvm-libm | llvm-libm | cuda-math | hip-math |
+| | | | (AMDGPU) | (CUDA) | (CUDA) | (AMDGPU) |
++========================+=============+===============+====================+====================+====================+====================+
+| acos | Randomized | 4 | 6 (FAILED) | 6 (FAILED) | 1 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| acosf | Exhaustive | 4 | 1 | 1 | 1 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| acosf16 | Exhaustive | 2 | 1 | 1 | | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| acoshf | Exhaustive | 4 | 1 | 1 | 2 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| acoshf16 | Exhaustive | 2 | 0 | 0 | | 0 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| acospif16 | Exhaustive | 2 | 0 | 0 | | |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| asin | Randomized | 4 | 6 (FAILED) | 6 (FAILED) | 2 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| asinf | Exhaustive | 4 | 1 | 1 | 1 | 3 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| asinf16 | Exhaustive | 2 | 0 | 0 | | 2 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| asinhf | Exhaustive | 4 | 1 | 1 | 2 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| asinhf16 | Exhaustive | 2 | 1 | 1 | | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| atanf | Exhaustive | 5 | 0 | 0 | 1 | 2 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| atanf16 | Exhaustive | 2 | 1 | 1 | | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| atan2f | Randomized | 6 | 1 | 1 | 2 | 3 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| atanhf | Exhaustive | 5 | 0 | 0 | 3 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| atanhf16 | Exhaustive | 2 | 0 | 0 | | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| cbrt | Randomized | 2 | 1 | 1 | 1 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| cbrtf | Exhaustive | 2 | 0 | 0 | 1 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| cos | Randomized | 4 | 1 | 1 | 2 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| cosf | Exhaustive | 4 | 1 | 1 | 2 | 2 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| cosf16 | Exhaustive | 2 | 1 | 1 | | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| coshf | Exhaustive | 4 | 0 | 0 | 2 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| coshf16 | Exhaustive | 2 | 1 | 0 | | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| cospif | Exhaustive | 4 | 0 | 0 | 1 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| cospif16 | Exhaustive | 2 | 0 | 0 | | |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| erff | Exhaustive | 16 | 0 | 0 | 1 | 2 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| exp | Randomized | 3 | 1 | 1 | 1 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| expf | Exhaustive | 3 | 0 | 0 | 2 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| expf16 | Exhaustive | 2 | 1 | 1 | | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| exp10 | Randomized | 3 | 1 | 1 | 1 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| exp10f | Exhaustive | 3 | 0 | 0 | 2 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| exp10f16 | Exhaustive | 2 | 1 | 1 | | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| exp2 | Randomized | 3 | 1 | 1 | 1 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| exp2f | Exhaustive | 3 | 1 | 1 | 2 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| exp2f16 | Exhaustive | 2 | 1 | 1 | | 0 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| expm1 | Randomized | 3 | 0 | 0 | 1 | 2 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| expm1f | Exhaustive | 3 | 1 | 1 | 1 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| expm1f16 | Exhaustive | 2 | 1 | 1 | | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| hypot | Randomized | 4 | 0 | 0 | 2 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| hypotf | Randomized | 4 | 0 | 0 | 1 | 2 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| hypotf16 | Exhaustive | 2 | 0 | 0 | | |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| log | Randomized | 3 | 1 | 1 | 1 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| logf | Exhaustive | 3 | 1 | 1 | 1 | 2 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| logf16 | Exhaustive | 2 | 1 | 1 | | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| log10 | Randomized | 3 | 1 | 1 | 1 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| log10f | Exhaustive | 3 | 1 | 1 | 2 | 2 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| log10f16 | Exhaustive | 2 | 1 | 1 | | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| log1p | Randomized | 2 | 1 | 1 | 1 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| log1pf | Exhaustive | 2 | 1 | 1 | 1 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| log2 | Randomized | 3 | 1 | 1 | 1 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| log2f | Exhaustive | 3 | 0 | 0 | 1 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| log2f16 | Exhaustive | 2 | 1 | 1 | | 0 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| powf (integer exp.) | Randomized | 16 | 0 | 0 | 2 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| powf (real exp.) | Randomized | 16 | 0 | 0 | 2 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| sin | Randomized | 4 | 1 | 1 | 1 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| sinf | Exhaustive | 4 | 1 | 1 | 1 | 2 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| sinf16 | Exhaustive | 2 | 1 | 1 | | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| sincos (cos part) | Randomized | 4 | 1 | 1 | 2 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| sincos (sin part) | Randomized | 4 | 1 | 1 | 1 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| sincosf (cos part) | Exhaustive | 4 | 1 | 1 | 2 | 2 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| sincosf (sin part) | Exhaustive | 4 | 1 | 1 | 1 | 2 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| sinhf | Exhaustive | 4 | 1 | 1 | 3 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| sinhf16 | Exhaustive | 2 | 1 | 1 | | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| sinpif | Exhaustive | 4 | 0 | 0 | 1 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| sinpif16 | Exhaustive | 2 | 0 | 0 | | |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| tan | Randomized | 5 | 2 | 2 | 2 | 1 |
++------------------------+-------------+---------------+--------------------+--------------------+--------------------+--------------------+
+| tanf | Exhaustive | 5 | 0 | 0 | 3 ...
[truncated]
|
jhuber6
reviewed
Aug 31, 2025
I followed this suggestion from @lntue. |
|
The list of math functions will be quite big later, so probably they could be in a separate page to make other headers accessible. Also include the config that the GPU math functions are built with. |
I don't think we need to put the full support since we can just assume it's the same as with the CPU targets (generally no reason not to). Would it be easiest to just add an extra column for the GPU case in the existing documentation? Or maybe a separate table for the 'fast' versions. |
a separate table for the |
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lntue
reviewed
Sep 4, 2025
lntue
approved these changes
Sep 4, 2025
jhuber6
approved these changes
Sep 4, 2025
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This patch enhances the GPU support documentation page (
support.html) by adding a new, detailed section formath.h. This new section presents the results of the GPU math conformance tests, providing quantitative data on the accuracy of the supported higher math functions.