[llvm] [AArch64] Allow splitting bitmasks for EOR/ORR. (PR #150394)

[Paul Walker via llvm-commits]

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@@ -190,19 +191,48 @@ static bool splitBitmaskImm(T Imm, unsigned RegSize, T &Imm1Enc, T &Imm2Enc) {
   return true;
 }
 
+template <typename T>
+static bool splitDisjointBitmaskImm(T Imm, unsigned RegSize, T &Imm1Enc,
+                                    T &Imm2Enc) {
+  // Try to split a bitmask of the form 0b00000000011000000000011110000000 into
+  // two disjoint masks such as 0b00000000011000000000000000000000 and
+  // 0b00000000000000000000011110000000 where the inclusive/exclusive OR of the
+  // new masks match the original mask.
+  unsigned LowestBitSet = llvm::countr_zero(Imm);
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paulwalker-arm wrote:

Yes please.

https://github.com/llvm/llvm-project/pull/150394