[clang] [llvm] [X86] support reserve r8~r15 on X86_64 (PR #180242)

[Phoebe Wang via llvm-commits]

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@@ -515,6 +515,17 @@ BitVector X86RegisterInfo::getReservedRegs(const MachineFunction &MF) const {
   // Set the Shadow Stack Pointer as reserved.
   Reserved.set(X86::SSP);
 
+  auto &ST = MF.getSubtarget<X86Subtarget>();
+  if (ST.is64Bit()) {
+    for (size_t Reg = 0; Reg < getNumRegs(); Reg++) {
+      // Set r# as reserved register if user required
+      if (ST.isRegisterReservedByUser(Reg)) {
+        for (const MCPhysReg &SubReg : subregs_inclusive(X86::RSP))
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phoebewang wrote:

Why RSP?

https://github.com/llvm/llvm-project/pull/180242