[llvm] [CodeGen] Correctly handle non-standard cases in RemoveLoadsIntoFakeUses (PR #111551)

[Stephen Tozer via llvm-commits]

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@@ -94,11 +94,13 @@ bool RemoveLoadsIntoFakeUses::runOnMachineFunction(MachineFunction &MF) {
 
     for (MachineInstr &MI : make_early_inc_range(reverse(*MBB))) {
       if (MI.isFakeUse()) {
-        for (const MachineOperand &MO : MI.operands()) {
-          // Track the Fake Uses that use this register so that we can delete
-          // them if we delete the corresponding load.
-          if (MO.isReg())
-            RegFakeUses[MO.getReg()].push_back(&MI);
+        const MachineOperand &FakeUseOp = MI.getOperand(0);
+        // Track the Fake Uses that use this register so that we can delete
+        // them if we delete the corresponding load.
+        if (FakeUseOp.isReg()) {
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SLTozer wrote:

Yes - although there's no real meaning to non-register fake uses, at some points (that I don't recall off the top of my head) the operands can get replaced; it'd be equally valid to also just delete fake uses that have non-reg operands (and at any other point where we're examining fake uses).

https://github.com/llvm/llvm-project/pull/111551