[clang] [llvm] Intrinsic: introduce minimumnum and maximumnum (PR #93841)

[YunQiang Su via cfe-commits]

================
@@ -15883,6 +15883,95 @@ The returned value is completely identical to the input except for the sign bit;
 in particular, if the input is a NaN, then the quiet/signaling bit and payload
 are perfectly preserved.
 
+.. _i_fminmax_family:
+
+'``llvm.min.*``' Intrinsics Comparation
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Standard:
+"""""""""
+
+IEEE754 and ISO C define some min/max operations, and they have some differences
+on working with qNaN/sNaN and +0.0/-0.0. Here is the list:
+
+.. list-table::
+   :header-rows: 2
+
+   * - ``ISO C``
+     - fmin/fmax
+     - none
+     - fmininum/fmaximum
+     - fminimum_num/fmaximum_num
+
+   * - ``IEEE754``
+     - none
+     - nimNUM/maxNUM (2008)
+     - minimum/maximum (2019)
+     - minimumNumber/maximumNumber (2019)
+
+   * - ``+0.0 vs -0.0``
+     - either one
+     - +0.0 > -0.0
----------------
wzssyqa wrote:

Thanks. You are right.  I was confused by the hardware implementations of some hardware.
ARM/MIPSr6/PowerPC implement +0.0>-0.0.

https://github.com/llvm/llvm-project/pull/93841