[llvm] [X86][APX] Implement Windows APX ABI callee-saved registers per Microsoft spec (PR #200391)

[Phoebe Wang via llvm-commits]

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@@ -267,8 +273,10 @@ X86RegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
       return CSR_64_AllRegs_AVX_SaveList;
     return CSR_64_AllRegs_SaveList;
   case CallingConv::PreserveMost:
-    return IsWin64 ? CSR_Win64_RT_MostRegs_SaveList
-                   : CSR_64_RT_MostRegs_SaveList;
+    if (IsWin64)
+      return (HasEGPR ? CSR_Win64_APX_RT_MostRegs_SaveList
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phoebewang wrote:

Parentheses are redundant. The same for below.

https://github.com/llvm/llvm-project/pull/200391