The f16 forms of v_fma_mix threw for any FLOAT_MODE with an f16 rounding
other than to nearest even. ps5-opengl's shaders run with FLOAT_MODE
0xcc, f16 rounding toward zero with f16 denormals kept, so PPSA99005
stopped at its first draw (#2631).
The exact product-sum, already computed in f64 with round to odd, is now
rounded once in the mode's direction: scaled by the f16 step at its
exponent, truncated, floored or ceiled, and scaled back. A result beyond
65504 becomes infinity or 65504 as IEEE 754 gives for the direction. On
RDNA2 (gfx1036) -1.5 * 2^-24 + 2^-126 gives 0x8002 with round toward
-infinity, and this gives the same. Flushed f16 denormals still throw.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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