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fpu: implement Zfa minimum-number-or-NaN operations - #298
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fpu: implement Zfa minimum-number-or-NaN operations
Fixes #295
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Description
The Zfa
fminm/fmaxminstructions currently call the IEEE-754-2008fmin/fmaxhelpers. Those helpers return the numeric operand when one input is NaN, but the minimum-number-or-NaN instructions must return canonical NaN when either input is NaN. Add precision-specific helpers and preserve the existing numeric ordering and signaling-NaN flag behavior.The helpers already canonicalize NaN results, so the instruction handlers use
riscv_emit_s()/riscv_emit_d()for the final bit-precise writeback instead of canonicalizing the same value a second time.Validation
qemu-riscv64, Zfa) returns the canonical qNaN whenever either input is NaN; the patched build matches on the single- and double-precision one-NaN and two-NaN witnesses. The native reference does not implement Zfa and is recorded as a capability boundary.