[llvm] [AArch64] Legalize fp128 scalars as libcalls for G_FCMP (PR #98452)

[Thorsten Schütt via llvm-commits]

================
@@ -980,6 +979,150 @@ LegalizerHelper::createSetStateLibcall(MachineIRBuilder &MIRBuilder,
                        LocObserver, nullptr);
 }
 
+/// Returns the corresponding libcall for the given Pred and
+/// the ICMP predicate that should be generated to compare with #0
+/// after the libcall.
+static std::pair<RTLIB::Libcall, CmpInst::Predicate>
+getFCMPLibcallDesc(const CmpInst::Predicate Pred) {
+
+  switch (Pred) {
+  case CmpInst::FCMP_OEQ:
+    return {RTLIB::OEQ_F128, CmpInst::ICMP_EQ};
+  case CmpInst::FCMP_UNE:
+    return {RTLIB::UNE_F128, CmpInst::ICMP_NE};
+  case CmpInst::FCMP_OGE:
+    return {RTLIB::OGE_F128, CmpInst::ICMP_SGE};
+  case CmpInst::FCMP_OLT:
+    return {RTLIB::OLT_F128, CmpInst::ICMP_SLT};
+  case CmpInst::FCMP_OLE:
+    return {RTLIB::OLE_F128, CmpInst::ICMP_SLE};
+  case CmpInst::FCMP_OGT:
+    return {RTLIB::OGT_F128, CmpInst::ICMP_SGT};
+  case CmpInst::FCMP_UNO:
+    return {RTLIB::UO_F128, CmpInst::ICMP_NE};
+  default:
+    return {RTLIB::UNKNOWN_LIBCALL, CmpInst::BAD_ICMP_PREDICATE};
+  }
+}
+
+LegalizerHelper::LegalizeResult
+LegalizerHelper::createFCMPLibcall(MachineIRBuilder &MIRBuilder,
+                                   MachineInstr &MI,
+                                   LostDebugLocObserver &LocObserver) {
+  auto &MF = MIRBuilder.getMF();
+  auto &Ctx = MF.getFunction().getContext();
+
----------------
tschuett wrote:

```
GFCmp *Cmp = cast< GFCmp>(&MI);
```
to get access to the parameters.


https://github.com/llvm/llvm-project/pull/98452