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author | Andrew Waterman <andrew@sifive.com> | 2019-05-06 23:51:52 -0700 |
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committer | Andrew Waterman <andrew@sifive.com> | 2019-05-06 23:52:09 -0700 |
commit | 8772ea6f0f0e7136c21981d75ad25cd799a83c33 (patch) | |
tree | eae8ea15a316473a0261dac79536d9b9c3688db6 | |
parent | f02a75082ca87fed504792553dcb9d3c88b32404 (diff) | |
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Add note about FLE vs. BGE inconsistency
-rw-r--r-- | src/f.tex | 7 |
1 files changed, 7 insertions, 0 deletions
@@ -765,6 +765,13 @@ FCMP & S & src2 & src1 & EQ/LT/LE & dest & OP-FP \\ \end{tabular} \end{center} +\begin{commentary} +The F extension provides a $\leq$ comparison, whereas the base ISA provides +a $\geq$ branch comparison. Because $\leq$ can be synthesized from $\geq$ and +vice-versa, there is no performance implication to this inconsistency, but it +is nevertheless an unfortunate incongruity in the ISA. +\end{commentary} + \section{Single-Precision Floating-Point Classify Instruction} The FCLASS.S instruction examines the value in floating-point register {\em |