[llvm] [MemCpyOpt] Drop dead `memmove` calls on `memset`'d source data (PR #101930)

[via llvm-commits]

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@@ -1854,12 +1855,53 @@ bool MemCpyOptPass::processMemCpy(MemCpyInst *M, BasicBlock::iterator &BBI) {
   return false;
 }
 
+/// Memmove calls with overlapping src/dest buffers that come after a memset may
+/// be removed.
+bool MemCpyOptPass::mayBeMemMoveMemSetDependency(MemMoveInst *M) {
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DianQK wrote:

I guess this should be "must"?

https://github.com/llvm/llvm-project/pull/101930