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math_brute_force: fix fdim to use device's rounding when converting result back to half. (#2223)

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In the half-precision `fdim` test, the original code used `CL_HALF_RTE`
to convert the float result back to half, causing a mismatch in
computation results when the hardware uses RTZ. Some of the examples:
```
  fdim(0x365f, 0xdc63) = fdim( 0.398193f,  -280.75f)     =   281.148193f (RTE=0x5c65, RTZ=0x5c64)
  fdim(0xa4a3, 0xf0e9) = fdim(-0.018112f, 10056.0f)      = 10055.981445f (RTE=0x70e9, RTZ=0x70e8)
  fdim(0x1904, 0x9ab7) = fdim( 0.002449f,    -0.003279f) =     0.005728f (RTE=0x1dde, RTZ=0x1ddd)
```

Fixed this by using the hardware's default rounding mode when converting
the result back to half.
This commit is contained in:
Chuang-Yu Cheng
2025-01-29 05:33:00 +09:00
committed by GitHub
parent 73dd3b9af8
commit 5749818906
1 changed files with 8 additions and 3 deletions
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11
test_conformance/math_brute_force/binary_half.cpp
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@@ -266,6 +266,7 @@ cl_int TestHalf(cl_uint job_id, cl_uint thread_id, void *data)
return CL_SUCCESS;
}
cl_half_rounding_mode halfRoundingMode = CL_HALF_RTE;
FPU_mode_type oldMode;
oldRoundMode = kRoundToNearestEven;
if (isFDim)
@@ -275,7 +276,11 @@ cl_int TestHalf(cl_uint job_id, cl_uint thread_id, void *data)
if (ftz) ForceFTZ(&oldMode);
// Set the rounding mode to match the device
if (gIsInRTZMode) oldRoundMode = set_round(kRoundTowardZero, kfloat);
if (gIsInRTZMode)
{
oldRoundMode = set_round(kRoundTowardZero, kfloat);
halfRoundingMode = CL_HALF_RTZ;
}
}
if (!strcmp(name, "copysign")) copysign_test = 1;
@@ -293,9 +298,9 @@ cl_int TestHalf(cl_uint job_id, cl_uint thread_id, void *data)
s2[j] = cl_half_to_float(p2[j]);
if (isNextafter)
r[j] = cl_half_from_float(reference_nextafterh(s[j], s2[j]),
CL_HALF_RTE);
halfRoundingMode);
else
r[j] = cl_half_from_float(ref_func(s[j], s2[j]), CL_HALF_RTE);
r[j] = cl_half_from_float(ref_func(s[j], s2[j]), halfRoundingMode);
}
if (isFDim && ftz) RestoreFPState(&oldMode);