[llvm-branch-commits] [llvm] [AMDGPU] Update documentation for wave reduction intrinsics (PR #175132)

[Matt Arsenault via llvm-branch-commits]

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@@ -1378,19 +1378,87 @@ The AMDGPU backend implements the following LLVM IR intrinsics.
                                                    0: Target default preference,
                                                    1: `Iterative strategy`, and
                                                    2: `DPP`.
-                                                   If target does not support the DPP operations (e.g. gfx6/7),
+                                                   If the target does not support the DPP operations (e.g. gfx6/7),
                                                    reduction will be performed using default iterative strategy.
-                                                   Intrinsic is currently only implemented for i32.
+                                                   Intrinsic is implemented for i32 and i64 types.
+
+  llvm.amdgcn.wave.reduce.min                      Similar to `llvm.amdgcn.wave.reduce.umin`, but performs a signed min
+                                                   reduction on signed integers.
+                                                   Intrinsic is implemented for i32 and i64 types.
+
+  llvm.amdgcn.wave.reduce.fmin                     Similar to `llvm.amdgcn.wave.reduce.umin`, but performs a floating point min
+                                                   reduction on floating point values.
+                                                   Intrinsic is implemented for float and double types.
+                                                   NAN values are canonicalized.
+                                                   However if there are two consecutive NAN values, and the second value is a SNAN,
+                                                   wave_mode IEEE=False propogates the SNAN, while wave_mode IEEE=True quietens it.
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arsenm wrote:

This is in inaccurate way to state this. The issue is signaling nan quieting. I would just state the ordering of signaling nans is nondeterministic and ignore the issue 

https://github.com/llvm/llvm-project/pull/175132