[llvm] [clang] [SPARC] Support reserving arbitrary general purpose registers (PR #74927)

[Jessica Clarke via cfe-commits]

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@@ -1125,6 +1130,10 @@ Register SparcTargetLowering::getRegisterByName(const char* RegName, LLT VT,
     .Case("g4", SP::G4).Case("g5", SP::G5).Case("g6", SP::G6).Case("g7", SP::G7)
     .Default(0);
 
+  const SparcRegisterInfo *TRI = Subtarget->getRegisterInfo();
+  if (!TRI->isReservedReg(MF, Reg))
+    Reg = 0;
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jrtc27 wrote:

```not --crash```

Though  you need to be sure it will deterministically crash even in non-assertions release builds

https://github.com/llvm/llvm-project/pull/74927