[llvm] [AMDGPU] select v_sat_pk from two i16 or v2i16 (PR #121124)

[Pierre van Houtryve via llvm-commits]

================
@@ -3298,6 +3301,34 @@ def : GCNPat <
   (v2i16 (V_LSHL_OR_B32_e64 $src1, (i32 16), (i32 (V_AND_B32_e64 (i32 (V_MOV_B32_e32 (i32 0xffff))), $src0))))
 >;
 
+multiclass V_SAT_PK_Pat<Instruction inst> {
+  def: GCNPatIgnoreCopies<
+    (i16 (conc_lo_u8_i16 (clamp_s16_u8 i16:$lo), (clamp_s16_u8 i16:$hi))),
+    (inst
+      (V_LSHL_OR_B32_e64 VRegSrc_32:$hi, (S_MOV_B32 (i32 16)),
+      VRegSrc_32:$lo))
+  >;
+
+  def: GCNPatIgnoreCopies<
+    (i16 (conc_lo_u8_i16 (clamp_s16_u8 i16:$lo), (smax i16:$hi, (i16 0)))),
+    (inst
+      (V_LSHL_OR_B32_e64 VRegSrc_32:$hi, (S_MOV_B32 (i32 16)),
+      VRegSrc_32:$lo))
+  >;
+
+  def: GCNPatIgnoreCopies<
+    (i16 (conc_lo_v2i16_i16 (clamp_v2i16_u8 v2i16:$src))),
+    (inst VRegSrc_32:$src)
+  >;
+}
+
+let OtherPredicates = [NotHasTrue16BitInsts] in {
+  defm : V_SAT_PK_Pat<V_SAT_PK_U8_I16_e64>;
+} // End OtherPredicates = [NotHasTrue16BitInsts]
----------------
Pierre-vh wrote:

add a blank line between the two for readability

Also the `// End` comment is not really needed if the whole thing is just 3 lines IMO, so I'd remove it, but that's really a small nit

https://github.com/llvm/llvm-project/pull/121124