[llvm] [RISCV][TII] Add and use new hook to optimize/canonicalize instructions after MachineCopyPropagation (PR #137973)

[Alex Bradbury via llvm-commits]

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@@ -867,6 +867,12 @@ void MachineCopyPropagation::forwardUses(MachineInstr &MI) {
          make_range(Copy->getIterator(), std::next(MI.getIterator())))
       KMI.clearRegisterKills(CopySrcReg, TRI);
 
+    // Attempt to canonicalize/optimize the instruction now its arguments have
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asb wrote:

Ouch yes, I'd meant to place it outside the loop. Thanks for catching - now fixed.

https://github.com/llvm/llvm-project/pull/137973