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

[Sergei Barannikov via llvm-commits]

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@@ -98,9 +96,34 @@ BitVector SparcRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
   for (unsigned n = 0; n < 31; n++)
     Reserved.set(SP::ASR1 + n);
 
+  for (size_t i = 0; i < SP::IntRegsRegClass.getNumRegs() / 4; ++i) {
+    // Mark both single register and register pairs.
+    if (MF.getSubtarget<SparcSubtarget>().isGRegisterReserved(i)) {
+      Reserved.set(SP::G0 + i);
+      Reserved.set(SP::G0_G1 + i / 2);
+    }
+    if (MF.getSubtarget<SparcSubtarget>().isORegisterReserved(i)) {
+      Reserved.set(SP::O0 + i);
+      Reserved.set(SP::O0_O1 + i / 2);
+    }
+    if (MF.getSubtarget<SparcSubtarget>().isLRegisterReserved(i)) {
+      Reserved.set(SP::L0 + i);
+      Reserved.set(SP::L0_L1 + i / 2);
+    }
+    if (MF.getSubtarget<SparcSubtarget>().isIRegisterReserved(i)) {
+      Reserved.set(SP::I0 + i);
+      Reserved.set(SP::I0_I1 + i / 2);
+    }
+  }
+
   return Reserved;
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s-barannikov wrote:

Right, my mistake, I wrote from memory.
It should be asserted that it returns true, iirc.
Please see how other backends use it.

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