[llvm] [X86] Use RORX over SHR imm (PR #77964)

[Phoebe Wang via llvm-commits]

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@@ -891,6 +911,64 @@ let Predicates = [HasBMI2] in {
               (RORX32ri GR32:$src, (ROT32L2R_imm8 imm:$shamt))>;
     def : Pat<(rotl GR64:$src, (i8 imm:$shamt)),
               (RORX64ri GR64:$src, (ROT64L2R_imm8 imm:$shamt))>;
+
+    // A right shift by less than a smaller register size that is then
+    // truncated to that register size can be replaced by RORX to
+    // preserve flags with the same execution cost
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phoebewang wrote:

Add `.` in the end.

https://github.com/llvm/llvm-project/pull/77964