[llvm] [MachineLICM] Rematerialize instructions that may be hoisted before LICM (PR #158479)

[Matt Arsenault via llvm-commits]

================
@@ -167,3 +167,48 @@ bool llvm::isCycleInvariant(const MachineCycle *Cycle, MachineInstr &I) {
   // If we got this far, the instruction is cycle invariant!
   return true;
 }
+
+bool llvm::mayLoadFromGOTOrConstantPool(MachineInstr &MI) {
+  assert(MI.mayLoad() && "Expected MI that loads!");
+
+  // If we lost memory operands, conservatively assume that the instruction
+  // reads from everything..
+  if (MI.memoperands_empty())
+    return true;
+
+  for (MachineMemOperand *MemOp : MI.memoperands())
+    if (const PseudoSourceValue *PSV = MemOp->getPseudoValue())
+      if (PSV->isGOT() || PSV->isConstantPool())
----------------
arsenm wrote:

PSV->isConstant? Or MemOp->isInvariant? Not sure if we verify those are consistent 

https://github.com/llvm/llvm-project/pull/158479