[llvm] Add Instruction selection support for x87 ld/st (PR #97016)

[Thorsten Schütt via llvm-commits]

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@@ -195,6 +195,14 @@ X86InstructionSelector::getRegClass(LLT Ty, const RegisterBank &RB) const {
       return &X86::VR512RegClass;
   }
 
+  if (RB.getID() == X86::PSRRegBankID) {
+    if (Ty.getSizeInBits() == 80)
+      return &X86::RFP80RegClass;
+    if (Ty.getSizeInBits() == 64)
+      return &X86::RFP64RegClass;
+    return &X86::RFP32RegClass;
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tschuett wrote:

If I query for X86::PSRRegBankID and 31 bits, I would get X86::RFP32RegClass. This is bad. See the other groups. They check for all legal sizes.

https://github.com/llvm/llvm-project/pull/97016