[llvm] [CodeGen][Spill2Reg] Initial patch (PR #118832)

[Wei Xiao via llvm-commits]

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@@ -10893,5 +10947,208 @@ void X86InstrInfo::getFrameIndexOperands(SmallVectorImpl<MachineOperand> &Ops,
   M.getFullAddress(Ops);
 }
 
+bool X86InstrInfo::isLegalToSpill2Reg(Register Reg,
+                                      const TargetRegisterInfo *TRI,
+                                      const MachineRegisterInfo *MRI) const {
+  // Skip instructions like `$k1 = KMOVWkm %stack.1` because replacing stack
+  // with xmm0 results in an illegal instruction `movq  %k1, %xmm0`.
+  if (X86::VK16RegClass.contains(Reg))
+    return false;
+
+  switch (unsigned Bits = TRI->getRegSizeInBits(Reg, *MRI)) {
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williamweixiao wrote:

Are "double" and "float" legal here?

https://github.com/llvm/llvm-project/pull/118832